Phorbol ester up-regulates aldose reductase expression in A549 cells: a potential role for aldose reductase in cell cycle modulation

Over-expression of aldose reductase (AR) has been observed in many cancer cells. To clarify the role of AR in tumor cells, we investigated the pathways mediating expression of the AR gene induced by 12-O-tetradecanoylphorbol-13-acetate (TPA), a potent tumor promoter. In A549 human lung adenocarcinoma cells, TPA elicited a dose- and time-dependent increase in AR mRNA level with an elevated enzyme activity. The TPA-induced increase in mRNA level and promoter activity of the AR gene was significantly attenuated in the presence of an inhibitor of protein kinase C, tyrosine kinase, or nuclear factor kappaB (NF-kappaB). TPA augmented the NF-kappaB-dependent gene transcription, indicating the involvement of NF-kappaB in this regulation. Accumulation of TPA-treated cells in S phase was almost completely abolished in the presence of ethyl 1-benzyl-3-hydroxy-2(5H)-oxopyrrole-4-carboxylate, an AR inhibitor. Taken together, TPA augmented the promoter activity of the AR gene via the activation of protein kinase and NF-kappaB. The inhibition of AR may assist in the chemotherapy of malignant tumors by suppressing the rapid growth of cancer cells.

Tuberculin response in BCG vaccinated schoolchildren and the estimation of annual risk of infection in Hong Kong

BACKGROUND

In Hong Kong there has been nearly universal neonatal BCG vaccination coverage since 1980.

METHOD

21 113 schoolchildren aged 6-9 years were skin tested with one unit of tuberculin (PPD RT-23) using the intradermal technique during a routine BCG revaccination programme. Information on sex, date of birth, date of tuberculin testing, and tuberculin reaction size at 72 hours was retrieved. The annual risk of tuberculous infection (ARTI) was estimated by three different approaches.

RESULTS

Significantly higher tuberculin positive rates were found in girls and with increasing age at all commonly used cut-off points (5, 10, and 15 mm). Using a cut-off point of > or =10 mm and the formula 1- (1 - tuberculin positive rate)(1/age), the ARTI was estimated to be 1.93% (95% CI 1.84 to 2.03) for girls and 1.41% (95% CI 1.33 to 1.50) for boys. Using the differences in the tuberculin positive rate between the 6-7 year and 8-9 year age groups, the ARTI became 1.90% (95% CI 1.09 to 2.70) and 1.84% (95% CI 1.15 to 2.54) for girls and boys, respectively. When the prevalence of infection was estimated by locating a secondary peak of the tuberculin reaction distribution curve at 15 mm and assuming a symmetrical distribution of reaction sizes among those infected around this peak, the corresponding ARTI was much lower at 0.52% (95% CI 0.46 to 0.59) and 0.43% (95% CI 0.37 to 0.49) for girls and boys, similar to that estimated indirectly from the prevalence of disease.

CONCLUSION

The ARTI as estimated by conventional methods was unexpectedly high among BCG vaccinated children and did not agree with that anticipated from the annual incidence of active disease. Further studies are needed to address the discrepancies, including the possible interaction between BCG and other environmental stimuli.

Structural characteristics of purified beta-conglycinin from soybeans stored under four conditions

Four storage conditions including adverse conditions [84% relative humidity (RH), 30 degrees C], mild conditions (57% RH, 20 degrees C), cold conditions (4 degrees C), and uncontrolled ambient conditions were used for storing soybeans. The storage time was 9 months for the adverse conditions and 18 months for the other three conditions. Beta-conglycinin was purified and characterized with respect to its molecular properties. After storage under the adverse conditions, beta-conglycinin showed no significant changes in total sugar content, surface hydrophobicity, free SH and SS bonds, and amino acid composition within 6 months; however, it showed a significant decrease in surface hydrophobicity and a significant increase in total free SH and total SH including SS content after 6 months. Analysis of the secondary structure showed a significant increase in alpha-helix content, but a significant decrease in beta-sheet content after 3 months. For the other three conditions, no significant changes occurred to the structures of beta-conglycinin when compared to the control. The molecular mass of beta-conglycinin remained in the range of 199-212 kDa for all conditions during the entire storage periods.

Risk factors for defaulting from anti-tuberculosis treatment under directly observed treatment in Hong Kong

OBJECTIVE

To identify risk factors for defaulting from anti-tuberculosis treatment.

SETTING

Directly observed treatment in Hong Kong Government chest clinics.

DESIGN

Defaulters were recruited from a cohort of tuberculosis patients registered from 1 January to 31 March 1999. Three controls per case, matched for age and sex, were selected randomly from the cohort. Patient factors, initial tuberculosis characteristics and treatment-related variables were collected by review of medical records.

RESULTS

On matching 102 defaulters and 306 controls, a logistic risk model of default that considered patient factors, initial disease characteristics and treatment-related factors identified seven risk factors: current smoking (OR 3.00, 95% CI 1.41-6.39), past TB with default (OR 6.23, 95% CI 1.95-19.91), poor initial adherence (OR 117.21, 95% CI 13.52-1015.92), fair initial adherence (OR 11.02, 95% CI 2.15-56.43), unknown initial adherence (OR 6.59, 95% CI 3.47-12.49), treatment side effects (OR 13.30, 95% CI 3.23-54.79), and subsequent hospitalisation (OR 0.27, 95% CI 0.11-0.67). Its predictive power was 85%. Another model that considered only factors on registration for treatment gave a lower predictive power of 70%.

CONCLUSIONS

Treatment default could be predicted fairly accurately by considering patient and treatment-related factors.

Cluster characterisation and temporal expression of porcine sarcomeric myosin heavy chain genes

Members of the myosin heavy chain (MyHC) gene family are subjected to temporal regulation of gene switching during development. One strategy to the identification of cis-acting regulatory elements that are involved in temporal or fibre-type specific regulation is to undertake a comparative analysis of the MyHC gene family between the pig, an important target species, and other mammals, like human whose entire genome has been recently sequenced. Towards this end, we report here on the isolation, and characterisation of the porcine cardiac (MyHC slow/beta and alpha) and skeletal MyHC (embryonic, 2a, 2x, 2b and perinatal) gene clusters, and their structural comparisons with mouse and human clusters. The genome organisation of both clusters in the pig, human and mouse is conserved as having the same gene order, similar intergenic distances, and in the same head-to-tail orientation. For a period of pre-natal muscle growth, relative expression of MyHC isoforms, as determined by TaqMan real-time RT-PCR, correlated with the gene order in the skeletal MyHC cluster (embryonic > 2a > 2x > 2b) suggesting the possible presence of DNA elements on the same side as the MyHC embryonic gene that direct temporal regulation.

Socio-economic factors and tuberculosis: a district-based ecological analysis in Hong Kong

BACKGROUND

Relatively little is known about the impact of socio-economic factors on tuberculosis in a metropolitan city with high disease incidence.

METHOD

District-specific tuberculosis notification rates for 1995--1997 and 2000--2002 were indirectly sex- and age-adjusted and compared with the socio-economic characteristics in the 1996 by-census and 2001 census.

RESULTS

The differences between the 18 districts persisted after 3-year averaging and indirect standardisation. Only the percentage of population born locally, the percentage of the population widowed or divorced and the percentage of households residing in rooms or bedsits were consistently associated with the standardised notification ratios (SNR) for both periods, the first being negatively so (all P < 0.05). In a combined analysis with a general linear model for both periods, birth in China, residence <7 years, speaking other Asian languages, being married and in a single household were also significantly associated with the SNR (all P < 0.05). Using a backward conditional approach, only local birth, being married, and residing in rooms or bedsits were independent predictors of SNR (all P < 0.05). There was no significant association between SNR and socio-economic indices on education, occupation, unemployment and income.

CONCLUSION

Socio-economic factors other than simple poverty are affecting the district-specific tuberculosis rates in Hong Kong.

Smoking and tuberculosis in Hong Kong

OBJECTIVE

To study the relationship between smoking and tuberculosis in Hong Kong.

METHOD

Indirect sex and age adjustment was used to compare the prevalence of ever smokers between a sample of 851 patients from the 1996 tuberculosis notification registry and the general population. The clinical characteristics of smokers and non-smokers were compared by stratified univariate analysis and multiple logistic regression.

RESULTS

Tuberculosis patients were more likely to have smoked than population controls. The respective odds ratios for ever smoking between tuberculosis patients and population controls were 2.44 and 2.08 for males and females aged 16-64 (Mantel-Haenszel weighted OR = 2.40, P < 0.001), and 2.09 and 2.83 for males and females aged > or = 65 (Mantel-Haenszel weighted odds ratio = 2.19, P < 0.001). Male sex, age > or = 65, working at onset of illness, regular alcohol use, drug abuse and absence of contact history were associated with ever smokers (all P < 0.05). Ever smokers were more likely to have cough (OR 1.69), dyspnoea (OR 1.84), upper zone involvement (OR 1.67), cavity (OR 1.76), miliary lung involvement (OR 2.77), positive sputum culture (OR 1.43), but less isolated extrathoracic involvement (OR 0.31), even after controlling for the confounding background variables (all P < 0.05).

CONCLUSION

There was a consistent association between smoking and tuberculosis. More aggressive lung involvement was also found among ever smokers.

Development of a rapid titration method for predicting optimal coagulant concentration for filled tofu

A rapid titration method was developed for predicting the optimal coagulant concentration for making filled tofu. Cooked soymilk (350 mL, 20 degrees C) in a 400 mL beaker was stirred by a magnetic stirrer to form a swirl. The quick-acting coagulant solution (20.0 Brix) was added into the soymilk at 1.0 mL/min. The swirl depth decreased when the soymilk viscosity increased as a result of increasing the concentration of coagulant in the soymilk. At a suitable stirrer speed, the swirl finally disappeared but the soymilk still maintained rotation, and then the swirl reappeared after around 1 min. The critical point of coagulant concentration (CPCC) was calculated on the basis of the volume of coagulant consumed to get the swirl to disappear. The influences of several factors on the CPCC were investigated, including coagulant addition rate, soymilk temperature, soymilk concentration, soymilk volume, stir bar length, and container size. For validation, 33 soybean samples were used to determine their CPCCs and make filled tofus. The results indicated that CPCC was a characteristic parameter of soymilk and could be used as an effective indicator for predicting optimal coagulant concentration.

Identification of microsatellites in expressed muscle genes: assessment of a desmin (CT) dinucleotide repeat as a marker for meat quality

We investigated the presence of dinucleotide repeats (microsatellites) in a porcine skeletal muscle cDNA library. In total, microsatellites were found in nearly 4% of all muscle cDNA clones, of which CT- and TG-repeats were the most prevalent. We found a near full-length desmin cDNA clone with a CT-repeat sited downstream from its stop codon. From 44 commercially reared pigs, six allelic length polymorphisms were identified at this microsatellite locus (128, 131, 134, 135, 136, and 138 bp), whose desmin genotypes were associated with pH change after slaughter (P=0.031) and colour variation of meat (P<0.001 for hue, P<0.005 for lightness, and P=0.014 for b colour). Two of the genotypes (131/131 bp and 131/135 bp) were consistent with paler meat. This finding indicates the usefulness of the cDNA library approach to generate markers for marker-assisted selection and suggests that the desmin microsatellite could be a possible selection marker.

Signet-ring stromal tumor of the ovary: a case report

Signet-ring stromal tumor of the ovary is a rare disease and only four cases had been reported in the literature. The primary significance is to differentiate this benign disease from the malignant signet-ring adenocarcinoma. We report a case of signet-ring stromal tumor of the ovary in a 76-year-old woman who had suffered from low abdominal pain for one month. She underwent left oophorectomy, and the diagnosis was made based on immunohistochemical and electron microscopic characteristics. She has been well and free from recurrence for one year.

Molecular and quantitative characterisation of the porcine embryonic myosin heavy chain gene

The porcine embryonic myosin heavy chain (MyHC) is a major isoform in foetal skeletal muscle, and is the last remaining major porcine skeletal MyHC gene to be isolated and characterised. We report here on its cDNA and genomic isolation, molecular characterisation, quantification and expression. Unlike all other porcine and mammalian skeletal MyHC genes reported to date, the deduced translated start site of the porcine embryonic gene was located in exon 2, instead of exon 3. Its promoter conferred differentiation-specific expression. We found, by quantitative real-time RT-PCR, that for much of gestation the embryonic MyHC was by far the most transcriptionally active gene compared with the slow/I and perinatal MyHC isoforms, and it was consistently more highly expressed than the perinatal isoform throughout gestation. The embryonic MyHC isoform was, however, rapidly down-regulated at around birth. By contrast, 22 weeks after birth, the porcine perinatal isoform remained detectable by PCR. Additionally, we discovered the presence of differential splicing at the 3'-end of the embryonic MyHC gene that resulted in an in-frame deletion, with the consequential loss of 93 amino acids close to the ACD domain, a region that is important for the assembly of myosin filaments. The detection of this truncated variant points to a possible major post-transcriptional mechanism of embryonic MyHC regulation that may be linked to myosin filament formation or turnover.

Extracranial head and neck schwannomas: a review of 8 years experience

Schwannomas of the head and neck are uncommon tumors that arise from cranial, peripheral or autonomic nerves. In this study we review a series of 52 cases of schwannoma originating in the head and neck region over an 8-year period. All the tumors were benign, with the exception of one malignant schwannoma. The age range of the patients studied was 13-76 years and there was a predilection for males. Twenty-five schwannomas occurred in the scalp, face and external ear canal, 9 in the oral or nasal cavity and 18 in the neck. Seven cases of neck schwannoma originating from the major nerve system were found in the parapharyngeal space, all of which were located in the post-styloid compartment. Cervical plexus schwannomas originated either in the peripheral nerves or in an unidentified area of the nervous system; seven tumors were found in the posterior triangle of the neck and two in the anterior triangle. Two of the tumors originating in the brachial plexus were located in the posterior neck and one in the anterior neck. Tumors originating in the vagus nerve or sympathetic chain were all located in the anterior triangle of the neck.

Respiratory insufficiency in a Chinese adult with mitochondrial myopathy

Mitochondrial myopathy is an important but uncommon cause of respiratory insufficiency in adults. We report the first case of respiratory insufficiency associated with adult-onset mitochondrial myopathy seen in a Chinese adult in Hong Kong. The patient presented with peripheral oedema and shortness of breath over 2 to 3 days. There was a history of gradual progressive limb weakness over approximately 2 years, hypertrophic cardiomyopathy, intermittent diarrhoea, and weight loss. The diagnosis was made by skeletal muscle biopsy and molecular study, which revealed the A3243G point mutation.

Hypotensive effects of captopril on physical properties of the arterial system in young and adult rats

We determined the acute effects of the angiotension converting enzyme inhibitor captopril on the arterial mechanics in rats at different ages, based on the exponentially tapered T-tube model. Male Wistar-Kyoto rats aged 4 and 12 months were individually referred to as young (n = 8) and adult rats (n = 8) and were anesthetized and thoractomized. The pulsatile aortic pressure and flow signals before and after the administration of captopril (20 mg/kg, i.p.) were measured by a high-fidelity pressure sensor and an electromagnetic flow probe, respectively. In each age group, captopril showed little change in basal heart rate as well as cardiac output. However, captopril produced a drop of 15% in mean aortic pressure in young and a fall of 12% in adult rats. In addition. captopril reduced total peripheral resistance by 21% in young and by 23% in adult animals. As for the pulsatile nature of the arterial system, captopril had increased wave transit time of the lower body circulation of 10% in young and of 12% in adult rats. By contrast, captopril reduced wave reflection factor by 22% in young and by 25% in adult animals. In conclusion, the converting enzyme inhibitor captopril has a stiffness-decreasing effect on Windkessel vessels and a dilated effect on resistance arterioles in either young or adult rats. No age dependence of vascular response and reflex tachycardia to captopril has been found in rats between 4 and 12 months.

Spontaneous nanoscale corrugation of ion-eroded SiO2: the role of ion-irradiation-enhanced viscous flow

Grazing incidence x-ray scattering was used to determine the temperature and ion-energy dependence of nanoscale corrugations that form on an amorphous SiO2 surface eroded by Ar+ ions. The corrugation wavelength lambda* shows a nearly linear dependence on ion energy. Between room temperature and approximately 200 degrees C, lambda* depends weakly on temperature and above approximately 200 degrees C it shows an Arrhenius-like increase. Ion-assisted viscous relaxation in a thin surface layer is shown to be the dominant smoothing process during erosion; the rate of viscous smoothing scales as (lambda*)(-4).

Electrophysiological characteristics and radiofrequency ablation of focal atrial tachycardia originating from the superior vena cava

The initiation of focal atrial tachycardia (AT) from the superior vena cava (SVC) remains unclear. In 3 patients (2 females, 1 male; aged 57, 66 and 50 years, respectively) with focal AT arising from different parts of the SVC, the AT occurred spontaneously, rather than being induced by electrical stimulation. The cycle length of the tachycardia was highly variable, ranging between 190 and 300 ms in patient 1, 180 and 320ms in patient 2, and 200 and 300ms in patient 3. The clinical or associated arrhythmias were atrial fibrillation (AF) (patients 1, 3) and atrial flutter (AFL) (patients 2, 3). A presumed SVC potential that was earlier than the activation of all the other mapping sites was recorded during AT at the lower anterior (15-mm above the atriocaval junction), the mid-anterior (25-mm above the atriocaval junction) and the lower posterior aspect of the SVC (17-mm above the atriocaval junction. Radiofrequency (RF) ablation targeting the SVC focus with the SVC potential promptly eliminated the focal AT in all 3 patients. The coexistent typical AFL was ablated, but the AF was not. The follow-up period was 6, 6, and 3 months, respectively, for each of the patients under no antiarrhythmic medication; there has not been a recurrence of symptomatic palpitation. In conclusion, focal electrical firing in the SVC can initiate AT and this type of focal AT is always associated with AFL or AF. RF ablation guided by the presumed SVC potential is safe and highly effective in eliminating the tachycardia.

Antithrombotic effects of YS-49 and YS-51--1-naphthylmethyl analogs of higenamine

The antiplatelet and antithrombotic effects of YS-49 and YS-51--l-naphthylmethyl analogs of higenamine, which is a benzyl-tetrahydroisoquinoline alkaloid isolated from Aconitum japonicum (Ranunculaceae)--were investigated. YS-49 and YS-51 showed inhibitory activities to both human and rat platelet aggregation induced by ADP, collagen and epinephrine. They were more inhibitory to epinephrine-induced aggregation (IC(50); 3.4 and 1.7 microM of YS-49, and 6.0 and 6.3 microM of YS-51 to human and rat platelets, respectively) than ADP- or collagen-induced aggregation. The antithrombotic effects of YS-49 and YS-51 were also observed in both mouse acute thrombosis model and rat arterio-venous shunt (AV shunt) model. The oral administration of YS-49 and YS-51 (50 or 100 mg/kg) increased the recovery rates from the acute thrombotic challenge in mice and lowered the weight of thrombus formed inside the AV shunt tube in rats.

Identification of genes associated with natural competence in Helicobacter pylori by transposon shuttle random mutagenesis

To identify genes involved in DNA transformation, we generated 1500 insertion mutants of a Helicobacter pylori strain by transposon shuttle mutagenesis. All mutant strains were screened for their frequency of natural transformation. A total of 20 mutant strains were found to exhibit a significantly decreased transformation frequency. DNA sequencing revealed seven genetic loci, including the reported comB locus, HP0017 (a putative virB4 homologue) and five loci without database match (HP0015, HP1089, HP1326, HP1424, and HP1473) from the 20 mutants. Reknockout of HP1326 revealed no impairment in natural transformation, while the other 5 mutants showed the same defective in natural transformation. Mutation of HP0017 severely impaired natural transformation both chromosome and plasmid DNA. Slot blot analysis revealed that some noncompetent strains had decreased virB4 RNA expression levels compared with competent strains. Nineteen ORFs had decreased expression levels in virB4 knockout mutant by microarray. Therefore, our data indicate that HP0017 is a virB4 homologue and is essential in the natural competence of H. pylori. HP0015, HP1089, HP1424, and HP1473 genes could be also involved in natural transformation.

GTPase stimulation in shrimp Ras(Q(61)K) with geranylgeranyl pyrophosphate but not mammalian GAP

BALB/3T3 cells were transformed by transfection with DNA encoding the mutated ras(Q(61)K) from shrimp Penaeus japonicus (Huang et al., 2000). The GTPase-activating protein (GAP) in the cytosol fraction was significantly expressed and degraded, compared to untransformed cells on the western blot. To understand this in more detail, the interaction of the bacterially expressed shrimp Ras (S-Ras) with GAP was investigated using GAP purified from mouse brains. SDS-polyacrylamide gel electrophoresis revealed the monomers of the purified GAP to have a relative mass of 65,000. Since the purified GAP was bound to the Ras conjugated affinity sepharose column with high affinity and its GTP hydolysis activity upon binding with tubulin was suppressed, the purified enzyme was concluded to be neurofibromin-like. The purified GAP enhanced the intrinsic GTPase activity of the S-Ras, to convert it into the inactive GDP-bound form, in agreement with findings for GTP-bound K(B)-Ras in vitro. To compare the effects between isoprenoids and GAP on the GTP-hydrolysis of Ras, we applied the GTP-locked shrimp mutant S-Ras(Q(61)K) and GTP-locked rat mutant K(B)-ras(Q(61)K). Radioassay studies showed that geranylgeranyl pyrophosphate at microg level catalyzed the GTP hydrolysis of S-Ras(Q(61)K) and K(B)-ras(Q(61)K) competently, but not farnesyl pyrophosphate or the purified GAP. The present study provides the view that the geranylgeranyl pyrophosphate at carboxyl terminal CAAX assists GTP hydrolysis to Ras proteins probably in a manner similar to the substrate assisted catalysis in GTPase mechanism.

Lack of relation between severity of stroke and severity of extracranial internal carotid artery lesions in Taiwanese first-ever ischemic stroke patients

BACKGROUND AND PURPOSE

The authors attempt to determine whether hemodynamically significant extracranial internal carotid artery (ICA) lesions correlate with the severity of first-ever hemispheric ischemic stroke.

METHODS

Carotid duplex was used to evaluate carotid arteries. The National Institutes of Health Stroke Scale was used to describe the severity of the stroke and was stratified as follows: 1-6 = mild, 7-15 = moderate, > 15 = severe. Duplex findings were categorized according to velocity criteria into < 50% stenosis if ICA peak systolic velocity (PSV) (cm/s) < 140 and > 50% stenosis if ICA PSV > 140 or ratio of ICA and common carotid artery in PSV > 2. No detectable flow at ICA was considered occlusion. Stroke subtype was classified according to TOAST criteria.

RESULTS

Two hundred nineteen consecutive patients were enrolled, including 127 with mild, 65 with moderate, and 27 with severe stroke. The prevalence of ICA stenosis > 50% in each group was 3.6%, 1.4%, 0.9%, respectively. Two patients in the severe group had total ICA occlusion. The overall prevalence of significant ICA lesions was 6.8%.

CONCLUSIONS

There is no positive correlation of stroke severity with the severity of duplex findings, which may be due to low prevalence of significant ICA lesions or other stroke mechanisms. Most of the patients had mild stroke, and the majority had ICA stenosis < 50%. Small-vessel occlusion tended to have mild severity of stroke. Intracranial artery lesions or other factors causing stroke in Taiwanese should be investigated. Given the low incidence of significant extracranial carotid disease in symptomatic Taiwanese stroke patients, routine screening of symptomatic Taiwanese for extracranial carotid artery disease does not provide enough information to determine stroke mechanism, and transcranial Doppler should be added to the screening tests.

Anti-thrombotic effects of higenamine

The anti-platelet and anti-thrombotic effects of higenamine, a benzyltetrahydroisoquinoline alkaloid of the roots of Aconitum japonicum (Ranunculaceae), were investigated. The degree of platelet aggregation was measured with platelet rich plasma (PRP). An acute thrombotic condition was induced in mice by the injection of the mixture of collagen and epinephrine. The thrombus formation was induced inside the arterio-venous shunt tube installed between an abdominal aorta and the renal vein of rats. Higenamine showed inhibitory activities to both human and rat platelet aggregation induced by ADP, collagen and epinephrine. It was more inhibitory to epinephrine induced aggregation (IC(50); 19 and 7.2 microM to human and rat platelets respectively) than ADP- or collagen-induced aggregation. The anti-thrombotic effects of higenamine were also observed in both mouse acute thrombosis model and rat arterio-venous shunt (AV-shunt) models. The oral administration of higenamine (50 or 100 mg/kg) increased the recovery rates from the acute thrombotic challenge in mice and lowered the weight of thrombus formed inside the AV-shunt tube in rats.

Sepsis-induced apoptosis causes progressive profound depletion of B and CD4+ T lymphocytes in humans

Patients with sepsis have impaired host defenses that contribute to the lethality of the disorder. Recent work implicates lymphocyte apoptosis as a potential factor in the immunosuppression of sepsis. If lymphocyte apoptosis is an important mechanism, specific subsets of lymphocytes may be more vulnerable. A prospective study of lymphocyte cell typing and apoptosis was conducted in spleens from 27 patients with sepsis and 25 patients with trauma. Spleens from 16 critically ill nonseptic (3 prospective and 13 retrospective) patients were also evaluated. Immunohistochemical staining showed a caspase-9-mediated profound progressive loss of B and CD4 T helper cells in sepsis. Interestingly, sepsis did not decrease CD8 T or NK cells. Although there was no overall effect on lymphocytes from critically ill nonseptic patients (considered as a group), certain individual patients did exhibit significant loss of B and CD4 T cells. The loss of B and CD4 T cells in sepsis is especially significant because it occurs during life-threatening infection, a state in which massive lymphocyte clonal expansion should exist. Mitochondria-dependent lymphocyte apoptosis may contribute to the immunosuppression in sepsis by decreasing the number of immune effector cells. Similar loss of lymphocytes may be occurring in critically ill patients with other disorders.