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June 2004
Editors:
Michael Bissell, MD, PhD, MPH, professor and director of clinical services and vice chair, Department of Pathology, Ohio State University Medical Center, Columbus
Ronald Domen, MD, professor of pathology, medicine, and humanities, Penn State University College of Medicine, Hershey, Pennsylvania
Molecular epidemiology of tuberculosis
Assessing the significance of microscopic hematuria
Plasma adenosine as a preeclampsia marker
Preeclampsia, HELLP syndrome, and genetic coagulation markers
Lipopolysaccharide-binding protein in amnionitis
Changes in HIV-1 associated with herpes simplex virus
Adherence of Streptococcus pneumoniae to tracheal epithelium
Adenosine deaminase and tuberculosis
Resistance to mycoplasma infection
Molecular epidemiology of tuberculosis
Restriction fragment length polymorphism typing of tuberculosis using the insertion sequence IS6110 has greatly aided epidemiological studies of tuberculosis. Epidemiologically related isolates will have identical banding patterns; thus indistinguishable strains generally can be assumed to represent recently transmitted infection rather than reactivation. They can, however, reflect reactivation of strains that were more common in the past. Furthermore, identical banding patterns may occur as a result of preferred insertion sites. Still, the technique has proved useful in many parts of the world for exploring the epidemiology of tuberculosis. Between 1992 and 1998, the tuberculosis notification rate in London rose from 23 to 35 per 100,000 individuals, representing 42 percent of notifications in England and Wales in 1998. Previous studies in England and Wales have suggested that poverty or ethnic origin were important reasons for the increased incidence of tuberculosis. Tuberculosis and HIV co-infection has been increasing in parts of London, and recent reports have suggested that HIV may be contributing to this rise. The authors undertook a multicenter study in London to describe the restriction fragment length polymorphism (RFLP) patterns of isolates of Mycobacterium tuberculosis from July 1995 through 1997. This was done to assess the degree of apparent recent transmission, identify subpopulations with high rates of recent transmission, and determine the magnitude of potential risk factors associated with recent transmission. M. tuberculosis isolates from all persons from Greater London diagnosed with culture-positive tuberculosis between July 1, 1995 and Dec. 31, 1997 were genetically fingerprinted using IS6110 RFLP typing. A structured proforma was used during record review of cases of culture-confirmed tuberculosis. Cluster analysis was performed and risk factors for clustering were examined in a univariate analysis followed by a logistic regression analysis with membership of a cluster as the outcome variable. RFLP patterns were obtained for 2,042 isolates with more than four copies of IS6110; 463 (22.7 percent) belonged to 169 molecular clusters, which ranged in size from two (65 percent of clusters) to 12 persons. The estimated rate of recent transmission was 14.4 percent. Independently associated with an increased risk of clustering were age ranging from birth to 19 years (odds ratio, 2.65; 95 percent confidence interval 1.59 to 4.44), birth in the United Kingdom (odds ratio, 1.55; 95 percent confidence interval 1.04 to 2.03), black Caribbean ethnic group (odds ratio, 2.19; 95 percent confidence interval 1.15 to 4.16), alcohol dependence (odds ratio, 2.33; 95 percent confidence interval 1.46 to 3.72), and streptomycin resistance (odds ratio, 1.82; 95 percent confidence interval 1.15 to 2.88). The authors concluded that cases of tuberculosis in London are largely caused by reactivation or importation of infection by recent immigrants. Newly acquired infection is also common among people with recognized risk factors.
Maguire H, Dale JW, McHugh TD, et al. Molecular epidemiology of tuberculosis
in London 1995-7 showing low rate of active transmission. Thorax. 2002;57:617-622.
Reprints: Dr. T.D. McHugh, Dept. of Medical Microbiology, Royal Free & University
College Medical School, Royal Free Campus, London NW3 2PF, United Kingdom; tmchugh@rfc.ucl.ac.uk
Assessing the significance of microscopic hematuria
Asymptomatic microscopic hematuria, commonly detected in adults, is associated with causes ranging from insignificant to potentially life-threatening neoplastic lesions. Microscopic hematuria, therefore, may indicate the presence of bladder cancer, the second most common cancer of the genitourinary tract. Consequently, it is necessary to fully investigate patients presenting with microscopic hematuria to exclude an underlying genitourinary malignancy. Urine analysis with dipsticks is widely used in health-screening clinics and routine clinical practice, resulting in increased referral of patients with microscopic hematuria to urologists for further investigation. A combination of cystoscopy, ultrasonography of the renal tract, intravenous urography, urine culture, and cytology is considered appropriate for evaluating these patients. The authors retrospectively and prospectively studied patients with microscopic hematuria who attended a hematuria clinic to determine the prevalence of urological pathology. Between January 1998 and May 2001, 781 patients attended the hematuria clinic, and of these, 368 (47 percent; median age, 60 years; range, 18 to 90) had a history of microscopic hematuria as detected by urine dipstick testing. These patients were investigated by urine culture and cytology, renal ultrasonography, intravenous urography, flexible cystoscopy, urea and electrolyte analysis, and assay of prostate specific antigen where appropriate. Urine cytology showed no malignant cells in any patient with a history of microscopic hematuria. In 143 patients (39 percent), urine cytology showed no red blood cells, and all other investigations were normal. In the remaining 225 patients, intravenous urography showed a tumor in one (bladder), renal stones in 15, and an enlarged prostate in two. Renal ultrasonography detected no additional pathology. Urine analysis showed one urinary tract infection. Flexible cystoscopy detected five patients with a bladder tumor (all G1pTa), two urethral strictures, five bladder stones and enlarged prostates, six enlarged prostates only, and nine red patches in the bladder, showing one patient with carcinoma in situ. PSA levels did not suggest prostate cancer. The authors concluded that patients with dipstick-positive hematuria should be reassessed by urine microscopy before referral. Because only 1.4 percent of patients had a malignant pathology (all noninvasive), microscopic hematuria should be regarded as a separate entity from macroscopic hematuria, and such patients do not need to be referred urgently.
Khan MA, Shaw G, Paris AMI. Is microscopic haematuria a urological emergency?
BJU International. 2002;90:355-357.
Reprints: Dr. M.A. Khan, research fellow, Dept. of Urology, Johns Hopkins Hospital,
600 N. Wolfe St., Baltimore, MD 21287; ktasmas@aol.com
Plasma adenosine as a preeclampsia marker
Levels of several neurohumoral factors are reported to correlate with preeclampsia.
Plasma norepinephrine and other catecholamines are increased in the toxemia.
There are also elevated concentrations of cytokines such as tumor necrosis factor-a
in plasma and amniotic fluid in severe preeclampsia. Increased plasma concentrations
and inappropriate responses to these and other unknown agents have been proposed
to be involved in the pathogenesis of the toxemia. Adenosine has many important
physiologic roles, a number of which directly oppose the actions of excessive
concentrations of catecholamines and cytokines. Maternal plasma adenosine concentration
is increased in normal pregnancy and preeclampsia, and the increase is greater
in preeclampsia than in normal pregnancy. The authors hypothesized that elevated
plasma adenosine concentration in preeclampsia is an endogenous compensatory
response that diminishes the deterioration of preeclampsia induced by excessive
release of catecholamines and tumor necrosis factor-a. The authors measured
plasma concentrations of adenosine, norepinephrine, and TNF-a in women with
mild (n=21) and severe (n=21) preeclampsia and normal pregnancies (n=21) who
were matched for age, gestational age, and parity in the third trimester of
pregnancy. They then evaluated the relationships among the analyte concentrations
and the severity of preeclampsia. Mean plasma adenosine, norepinephrine, and
tumor necrosis factor-a concentrations were significantly higher in women with
mild and severe preeclampsia than in normal control subjects (P<0.5). In women
with preeclampsia, plasma adenosine concentrations increased according to the
severity of the preeclampsia (0.60 ± 0.03 µmol/L and 0.72 ± 0.03 µmol/L, respectively,
versus 0.41 ± 0.03 µmol/L for normal subjects), which correlated with increases
of norepinephrine and TNF-a concentrations (r=.58; P<0.5;
r=.49; P<.05, respectively). In preeclampsia, norepinephrine
concentration also correlated with maternal blood pressure (r=.50;
P<.05). The authors concluded that increased plasma concentrations of adenosine
in preeclampsia might counteract further progression of the complication.
Yoneyama Y, Suzuki S, Sawa R, et al. Increased plasma adenosine concentrations
and the severity of preeclampsia. Obstet Gynecol. 2002;200:1266-1270.
Reprints: Dr. Yoshio Yoneyama, Nippon Medical School, Dept. of Obstetrics and
Gynecology, 1-1-5, Sendagi, Bunkyo-ku, Tokyo, 113-8603, Japan; yoshi-1@nms.ac.jp
Preeclampsia, HELLP syndrome, and genetic coagulation markers
Preeclampsia is associated with intervillous and spiral artery thrombosis,
vascular endothelium damage, and abnormalities of coagulation leading to inadequate
maternal, fetal, and placental circulation. Moreover, some of the most important
complications of the syndrome, such as HELLP syndrome (distinguished by hemolysis,
elevated liver enzymes, and low platelets) and disseminated intravascular coagulation,
are characterized by marked clotting disturbances. It has been hypothesized
that mutations predisposing patients to thrombosis may be important risk factors
for preeclampsia and its complications related to inadequate maternal-fetal
circulation. The carriers of the point mutation R506Q in factor V (Leiden mutation),
which leads to activated protein C (APC) resistance, are at increased risk of
thrombosis. Previous studies have investigated the possible pathogenic role
of APC resistance and factor V Leiden or factor II G20210A in preeclampsia.
The results, however, are contradictory. Therefore, the authors attempted to
estimate the prevalence of factor V Leiden and factor II G20210A in a group
of normal pregnant women and subjects with preeclampsia who were selected using
strict and well-defined criteria from a white Caucasian population. A 24-month
case-control study was performed on 111 subjects with preeclampsia and 111 normal
pregnant women matched for age and parity who did not have previous thromboembolic
disorders. The subjects were tested for the mutation A1691G in the factor V
gene (R506Q or Leiden mutation) and the mutation G20210A in the factor II (prothrombin)
gene. The Student's t-test and the x2-test were applied
when appropriate, and odds ratios and 95 percent confidence intervals were calculated.
Fourteen patients with preeclampsia (12.6 percent) had at least one of the two
mutations, compared with six controls (5.4 percent). Factor V Leiden was found
in eight patients with preeclampsia (7.2 percent) and five controls (4.5 percent).
Factor II G20210A was detected in eight preeclamptic women (7.2 percent) and
one normal pregnant woman (0.9 percent; P=0.041). In the subgroup of 32 preeclamptic
subjects with HELLP syndrome, factor V Leiden was found in three patients (9.3
percent) and factor II G20210A in two (6.2 percent). The authors concluded that
the prevalence of factor V and factor II mutations is increased in patients
with preeclampsia, and the thrombophilic mutations may interact with other pathogenic
factors to determine the clinical features of the disease and its complications.
Benedetto C, Marozio L, Salton L, et al. Factor V Leiden and Factor II G20210A
in preeclampsia and HELLP syndrome. Acta Obstet Gynecol Scand. 2002;81:1095-1100.
Reprints: Chiara Benedetto, Dept. of Gynecology and Obstetrics, University of
Turin, Via Baiardi 43, 10126 Turin, Italy; chbened@tin.it
Lipopolysaccharide-binding protein in amnionitis
Bacterial lipopolysaccharide or endotoxin is a component of the cell wall
of Gram-negative bacteria, which has been implicated in the pathophysiology
of preterm labor, preterm premature rupture of membranes, chorioamnionitis,
and septic shock. The molecular mechanism by which bacterial lipopolysaccharide
(LPS) induces a cellular response has been partially defined. LPS binds to an
acute-phase reactant protein, known as LPS-binding protein (LBP), to form an
LPS-LBP complex that binds to CD14, a receptor present on the surface of neutrophils,
monocytes, and macrophages. The interaction of CD14 with the LPS-LBP complex
initiates signal transduction with apparent participation of Toll-like receptor-4
(TLR-4). This eventually leads to activation of the mitogen-activated protein
kinase (MAP-kinase) and nuclear factor (NF)-kB pathways. These events result
in the production of proinflammatory cytokines such as interleukin-1b and tumor
necrosis factor (TNF)-a, leading to an inflammatory response. A second accepted
role of LBP is the transportation of LPS into high-density lipoprotein (HDL)
particles, resulting in LPS neutralization. The authors conducted a study to
examine the relationship between amniotic fluid concentrations of LBP and microbial
invasion of the amniotic cavity (MIAC), spontaneous parturition (term and preterm),
and ruptured or intact membranes. They also explored the relationship between
amniotic fluid concentrations of LBP and subsequent fetal loss in patients undergoing
mid-trimester amniocentesis. Amniotic fluid was retrieved by amniocentesis from
343 patients in the following groups: those in mid-trimester with a subsequent
normal pregnancy outcome (n=84); those in mid-trimester with fetal
loss after the procedure (n=10); those with preterm labor and intact
membranes without MIAC who delivered at term (n=36) or prematurely
(n=52), and those with preterm labor with MIAC (n=26); those with preterm
premature rupture of membranes with (n=26) and without (n=26)
MIAC; and those delivering at term with intact membranes in the absence of MIAC
in labor (n=52) and not in labor (n=31). The concentration
of LBP in amniotic fluid was determined with a specific and sensitive immunoassay.
Nonparametric statistics were used, and a P value of less than 0.05 was considered
significant. LBP subsequently was detected in 98 percent (335 of 343) of the
amniotic fluid samples. MIAC was associated with a significant increase in amniotic
fluid concentration of LBP in women with preterm labor and intact membranes
but not in preterm premature rupture of membranes. Spontaneous preterm parturition
was associated with a significant increase in amniotic fluid concentration of
LBP. Patients who had a spontaneous fetal loss after mid-trimester amniocentesis
had a significantly higher median amniotic fluid LBP concentration than those
who had a mid-trimester amniocentesis and a normal perinatal outcome. The authors
concluded that preterm labor with MIAC and preterm parturition are associated
with higher amniotic fluid concentrations of LBP than preterm labor with sterile
amniotic fluid.
Espinoza J, Romero R, Chaiworapongsa T, et al. Lipopolysaccharide-binding protein
in microbial invasion of the amniotic cavity and human parturition. J Matern
Fetal Neonatal Med. 2002;12:313-321.
Reprints: Dr. R. Romero, Perinatology Research Branch, NICHD, Wayne State University/Hutzel Hospital, Dept. of Obstetrics and Gynecology, 4707 St. Antoine Blvd., Detroit, MI 48201
Changes in HIV-1 associated with herpes simplex virus
Herpes simplex virus is a significant pathogen in people infected with human
immunodeficiency virus. Seroepidemiologic studies have established that herpes
simplex virus (HSV) is among the most common viral infections in people with
HIV-1 infection. Over 60 percent of people who are at risk for HIV-1 are HSV-2
seropositive, including homosexual men and injection drug users. It recently
has been shown that HSV-2 infection is even more prevalent in developing countries
than in the United States or Europe. Among adults older than 30 years, rates
of HSV-2 infection in the Central African Republic, Tanzania, South Africa,
Zambia, Kenya, Uganda, and Zimbabwe are 82 percent, 60 percent, 82 percent,
and 74 percent, respectively. The role that HSV-2 infection plays in HIV disease
progression is controversial. A suggested mechanism for suppression affecting
HIV survival is a direct effect of specific HSV proteins on genes regulating
the rate of HIV-1 replication. In vitro, the HSV immediate early gene coding
for ICPO and ICP27 HSV has been shown to transactivate the long-terminal repeat
portion of the HIV genome, and coinfection of MT-4 cells with HSV and HIV can
lead to increased replication of HIV. An in vivo demonstration of this phenomenon
may be the observation that keratinocytes observed to be coinfected with HSV-1
and HIV show increased numbers of HIV virions compared with those cells infected
only with HIV. Data suggest that frequent HSV reactivation may influence the
replicating pool of HIV-1 and influence disease progression. Given the seroepidemiologic
studies suggesting that HSV is a nearly universal pathogen among those infected
with HIV-1 and the in vitro and in vivo data suggesting a significant interaction
between these two pathogens that may impact the natural history of HIV infection,
the authors examined the association between clinical and subclinical HSV reactivation
and HIV-1 RNA levels in plasma. They studied whether suppression of HSV alters
plasma HIV-1 RNA levels. HSV cultures were performed daily on HSV-2-positive/HIV-positive
patients, and plasma HIV-1 RNA loads were measured at regular intervals. A subset
of patients were measured prior to, during, and after HSV suppression with high-dose
acyclovir to determine whether HSV suppression was associated with a decrease
in HIV replication. Most (25 of 27 HSV-2-positive/HIV-positive persons) reactivated
HSV. Total HSV shedding rate was strongly correlated with plasma HIV-1 RNA load
(r=0.54; P=.004), and the plasma HIV-1 RNA level at a given
CD4 cell count was 48 percent lower when treated with acyclovir. These data
indicate that frequent mucosal HSV reactivation influences HIV replication in
vivo, and daily HSV suppression may be important in managing HSV-positive/HIV-positive
persons.
Schacker T, Zeh J, Hu H, et al. Changes in plasma human immunodeficiency virus
type 1 RNA associated with herpes simplex virus reactivation and suppression.
J Infect Dis. 2002;186:1718-1725.
Reprints: Dr. Timothy Schacker, Dept. of Medicine, University of Minnesota,
Box 250, 516 Delaware St. SE, Minneapolis, MN 55455; schac008@tc.umn.edu
Adherence of Streptococcus pneumoniae to
tracheal epithelium
Streptococcus pneumoniae neuraminidase activity may decrease the
viscosity of mucus or expose host epithelial cell surface receptors for S.
pneumoniae. Treatment of chinchilla tracheas with neuraminidase in vitro
increases S. pneumoniae adherence and reverses the inhibitory effects
of lato-N-neotetraose (LNnT), suggesting that neuraminidase treatment results
in an increase in the number of available receptors for S. pneumoniae.
Two S. pneumoniae neuraminidase genes, nanA and nanB,
have been cloned and sequenced, and a neuraminidase-deficient isogenic mutant,
ΔNA1, has been constructed by insertion-duplication mutagenesis of nanA.
To determine whether disruption of the nanA neuraminidase gene specifically
results in decreased adherence, the authors quantified the adherence of ΔNA1
and its parent strain, D39, to chinchilla tracheal epithelium. In addition,
they used lectin histochemistry to characterize changes in the cell surface
carbohydrate structure of the trachea epithelium induced by ΔNA1 or its
D39 parent to further explore the role of S. pneumoniae neuraminidase
in increasing the availability of S. pneumoniae receptors.The results
demonstrated that products of the nanA neuraminidase gene play a significant
role in the receptor-mediated adherence of S. pneumoniae to the chinchilla
trachea epithelium and also contribute to the alteration of the epithelial cell
surface carbohydrate architecture. Moreover, adherence data expressed as colony-forming
units of S. pneumoniae per millimeter of trachea indicated a significant
decline in the ability of ΔNA1 to adhere in vitro. The authors proposed
that products of the nanA gene have a significant impact on changes
in the carbohydrate moieties in the tracheal epithelium and may be responsible
for the previously reported increased ability of the D39 parent to colonize
the nasopharynx and invade the middle ear.
Tong HH, Liu X, Chen YP, et al. Effect of neuraminidase on receptor-mediated
adherence of Streptococcus pneumoniae to chinchilla tracheal epithelium.
Acta Otolaryngol. 2002;122:413–419.
Reprints: Dr. Thomas DeMaria, Division of Otologic Research, Dept. of Otolaryngology,
College of Medicine and Public Health, The Ohio State University, 4331 Cramblett
Hall, 456 W. 10th Ave., Columbus, OH 43210
Adenosine deaminase and tuberculosis
Pulmonary tuberculosis remains one of the leading causes of morbidity and
mortality worldwide. Although mycobacterial culture is sensitive and the standard
for diagnosing tuberculosis (TB), the time to diagnosis is a minimum of two
to three weeks, and the acid-fast bacilli (AFB) smear is insensitive for detecting
mycobacteria among TB patients with noncavitary disease. The increased serum
level of the enzyme adenosine deaminase (ADA, adenosine aminohydrolase, EC 3.5.4.4)
has been reported for viral and bacterial pneumonia, HIV infection, and extra-pulmonary
TB. Several diseases caused by intracellular microorganisms are characterized
by an elevated level of ADA in serum. Since Mycobacterium tuberculosis
infects lung macrophages, ADA may be released and detected in the serum of patients
with active pulmonary tuberculosis (PTB). There is limited data on the use of
serum ADA levels to diagnose active PTB in adults. The authors evaluated whether
total serum level of ADA or adenosine deaminase isoform 2 (ADA2)
activity can discriminate active PTB from other lung diseases and from healthy
lungs. ADA2 is produced by activated macrophages and has been used
to diagnose TB from extra-pulmonary sites. However, few studies adequately address
whether serum ADA2 activity is useful for diagnosing active PTB.
The authors prospectively measured serum ADA2 activity in 110 patients
with pulmonary disease (65 cases with active PTB and 45 cases with other respiratory
diseases) and 78 healthy volunteers (eight of whom were tuberculin skin-test
positive). The serum ADA2 for the diagnosis of PTB had a sensitivity
of 36.9 percent, specificity of 84.5 percent, positive predictive value of 10.9
percent, and negative predictive value of 96.2 percent. The authors concluded
that serum ADA2 activity is not useful for diagnosing active PTB
or differentiating it from other respiratory diseases.
Conde MB, Marinho SR, de Fatima Pereira M, et al. The usefulness of serum adenosine
deaminase 2 (ADA2) activity in adults for the diagnosis of pulmonary tuberculosis.
Resp Med. 2002;96:607-610.
Reprints: Dr. Marcus B. Conde. Av. Brigadeiro Trompowsky, s/n°, 3° andar, SME
da Pneumologia, Ilha do Fundão, Rio de Janeiro, RJ, Brazil, CEP 21941-590; marcusconde@
hucff.ufrj.br
Resistance to mycoplasma infection
Mycoplasma, an important human mucosal pathogen of the respiratory and urogenital
tracts, causes Mycoplasma pneumoniae respiratory disease. Even though
M. pneumoniae accounts for 8 million to 15 million cases of pneumonia
per year in the United States alone, there is no effective vaccine against the
disease because of a lack of good small-animal models. Mycoplasma pulmonis
respiratory infection in mice is perhaps the best paradigm of human disease.
Murine mycoplasma respiratory disease is caused by a pathogen in its normal
host, and the disease is characterized extensively. In murine mycoplasma respiratory
disease, the upper and lower respiratory tracts become infected after experimental
respiratory infections with M. pulmonis, making it an ideal model for
studying the impact of upper and lower respiratory tract immunity on the progression
of mycoplasma respiratory diseases. Studies support the premise that the nasal
route of immunization, which presumably induces respiratory immune response,
can protect individuals from developing mycoplasma disease, but such studies
are limited. In support of nasal immunization, mucosal antibody responses are
associated with resistance to mycoplasma infection in humans. However, it is
unclear whether immune responses generated in the upper and lower respiratory
tracts have similar impact or whether differences in induction of resistance
are present along the respiratory tract. The authors conducted a study to determine
whether local immunization of the respiratory tract protects against mycoplasma
infection and to compare preferential immunization of the upper respiratory
tract (nasal) with immunization of the upper and lower respiratory tracts (nasal-pulmonary).
Small volumes of inoculum preferentially deposited antigen and induced IgA responses
in nasal passages. Larger inoculums deposited antigen in the upper and lower
respiratory tracts, generating corresponding IgA responses. Mice were given
nasal or nasal-pulmonary immunizations with M. pulmonis antigen alone
or with cholera toxin, and resistance to infection was determined. Generation
of upper respiratory tract immunity reduced mycoplasma infection at this site,
but cholera toxin was needed to elicit protective responses. In the lower respiratory
tract, nasal-pulmonary immunization was most effective, but nasal immunization
did confer some protection from pulmonary infection. In contrast, intraperitoneal
immunization offered little protection. Thus, respiratory tract immunity plays
a major role in resisting mycoplasma infection, and it should be considered
in the process of developing a vaccine.
Hodge LM, Simecka JW. Role of upper and lower respiratory tract immunity in
resistance to mycoplasma respiratory disease. J Infect Dis. 2002;186:290-294.
Reprints: Dr. Jerry W. Simecka, Dept. of Molecular Biology and Immunology, University
of North Texas Health Science Center, 3500 Camp Bowie Blvd., Ft. Worth, TX 76107;
jsimecka@hsc.unt.edu
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