T cell recognition and tolerance of antibody diversity

The capacity of B cells to self-present their Ab variable regions in the context of class II MHC structures suggests a potential regulatory problem. If T cells were able to recognize self-presented Ab, then T cell help might be delivered to B cells independently of a foreign carrier epitope, resulting in a chronic state of unregulated Ab synthesis. For this reason, we have proposed that T cells normally attain a state of tolerance to Ab V region diversity. Here, we tested this idea by performing direct immunizations with unmutated isologous mAb. We also identified and analyzed epitopes recognized by class II MHC-restricted T cell hybridomas that were originally generated against two physiologically mutated isologous mAb. Our results indicate that the class II MHC-restricted T cell repertoire is tolerant of germ-line-encoded Ab diversity and that the physiologic somatic hypermutation process creates immunogenic epitopes in Ab V regions, in some cases by producing class II MHC-binding peptides. In agreement with these findings, we found that germ-line-encoded Ab V regions are presented by endogenous splenic APC at a level that is physiologically significant.     

Menstrual and reproductive factors and risk of breast cancer in Asian-Americans

We conducted a population-based case-control study of breast cancer among Chinese-, Japanese- and Filipino-American women in Los Angeles County Metropolitan Statistical Area (MSA), San Francisco-Oakland MSA and Oahu, Hawaii. One objective of the study was to quantify breast cancer risks in relation to menstrual and reproductive histories in migrant and US-born Asian-Americans and to establish whether the gradient of risk in Asian-Americans can be explained by these factors. Using a common study design and questionnaire in the three study areas, we successfully conducted in-person interviews with 597 Asian-American women diagnosed with incident, primary breast cancer during the period 1983-87 (70% of those eligible) and 966 population-based controls (75% of those eligible). Controls were matched to cases on age, ethnicity and area of residence. In the present analysis, which included 492 cases and 768 controls, we observed a statistically non-significant 4% reduction in risk of breast cancer with each year delay in onset of menstruation. Independent of age at menarche risk of breast cancer was lower (odds ratio; OR=0.77) among women with menstrual cycles greater than 29 days. Parous Asian-American women showed a significantly lower risk of breast cancer then nulliparous women (OR=0.54). An increasing number of livebirths and a decreasing age at first livebirth were both associated with a lower risk of breast cancer, although the effect of number of livebirths was no longer significant after adjustment for age at first livebirth. Women with a pregnancy (spontaneous or induced abortions) but no livebirth had a statistically non-significant increased risk (OR=1.84), but there was no evidence that one type of abortion was particularly harmful. A positive history of breastfeeding was associated with non-significantly lower risk of breast cancer (OR=.78). There are several notable differences in the menstrual and reproductive factors between Asian-Americans in this study and published data on US whites. US-born Asian Americans had an average age at menarche of 12.12 years-no older than has been found in comparable studies of US whites, but 1.4 years earlier than Asian women who migrated to the US. Asian-American women, particularly those born in the US and those who migrated before age 36, also had a later age at first birth and fewer livebirths than US whites. A slightly higher proportion of Asian-American women breastfed, compared with US whites. The duration of breastfeeding was similar in US-born Asians and US whites, but was longer in Asian migrants, especially those who migrated at a later age. Menstrual and reproductive factors in Asian-American women are consistent with their breast cancer rates being at least as high as in US whites, and they are. However, the effects of these menstrual and reproductive factors were small and the ORs for migration variables changed only slightly after adjustment for these menstrual and reproductive factors. These results suggest that the lower rates of breast cancer in Asians must be largely as a result of other environmental/lifestyle factors.     

Comparison of the degree of abdominal adhesion formation associated with chromic catgut and polypropylene suture materials

OBJECTIVE: To evaluate the histologic pattern and biomechanical properties of adhesions caused by chromic catgut and polypropylene sutures, using an enteropexy model. DESIGN: Enteropexies were created in dogs, using chromic catgut and polypropylene suture. The adhesions associated with the enteropexies were examined histologically and mechanically. ANIMALS: 6 mixed-breed dogs weighing 16 to 20 kg. PROCEDURE: 72 enteropexies were created between the jejunum and abdominal wall. 36 sites were sutured with chromic catgut and 36 were sutured with polypropylene. 3 dogs were euthanatized after 1 week. The remaining dogs were euthanatized after 1 month. Samples of the enteropexy sites were obtained for histologic examination. The remaining sites were mechanically distracted until failure of the enteropexy site or adjacent tissue occurred. RESULTS: Histologic examination of the enteropexy sites did not reveal substantial differences in the degree of inflammation between the 2 suture types at 1 week or 1 month. The degree of inflammation decreased and the maturity of fibrous tissue formed at the enteropexy sites increased for all specimens over time. No statistically significant difference in breaking strength was observed between suture types at 1 week or 1 month. CONCLUSION: In dogs, the formation and strength of intentionally created abdominal adhesions are not increased by use of chromic catgut. CLINICAL RELEVANCE: Selection of chromic catgut suture for use in surgical procedures where adhesions are desired is unwarranted.     

Biomarker assessment of the effects of petroleum refinery contamination on channel catfish

A series of arguments are presented that emphasize the importance of comparatively evaluating psychotherapies with appropriate pharmacotherapy and pill placebo. The lack of a pill-placebo arm has rendered moot those studies that compared pharmacotherapy directly with psychotherapy because of the lack of an internal sample defining calibration with regard to medication responsivity. The National Institute of Mental Health (NIMH) Treatment of Depression Collaborative Research Program is critically discussed because this program incorporated the recommended design features but still led to substantial controversy. The inclusion of a pill-placebo arm in future therapeutic studies is most desirable. NIMH should initiate a funded program specifically for multisite, pill-placebo-controlled studies of psychotherapy, pharmacotherapy, and their combination, jointly sponsored and supervised by skilled psychopharmacologists and psychotherapists.     

The indoor air and children''s health study: methods and incidence rates

The effect of chronic alcohol (33 mM ethanol) on Ca2+ signals elicited by glutamate receptor agonists (quisqualate and NMDA) was examined in developing cerebellar Purkinje and granule neurons in culture. The neurons were exposed to alcohol during the second week in culture, the main period of morphological and physiological development. The Ca2+ signals were measured with fura-2 based microscopic video imaging. Chronic exposure to alcohol during development significantly reduced the peak amplitude of the Ca2+ signals to quisqualate (1 microM; Quis) in both the somatic and dendritic regions of the Purkinje neurons. The dendritic region was affected to a greater extent than the somatic region. Granule neurons also showed a reduced somatic Ca2+ signal to Quis (dendrites not measured) in the alcohol-treated cultures, indicating that the effect was not limited to Purkinje neurons. In addition to the effects on in the response to Quis, the peak amplitude of the Ca2+ signals to NMDA (100 microM) was reduced by chronic alcohol exposure during development in both the cultured Purkinje and granule neurons. Resting Ca2+ levels were not consistently affected by alcohol treatment in either neuronal type. These results indicate that Ca2+ signaling linked to glutamate receptor activation is an important target of alcohol in the developing nervous system and could be a contributing factor in the altered CNS function and development observed in animal models of fetal alcohol syndrome.     

The scope and nature of the drowsy driving problem in New York State

A telephone survey was conducted of a random sample of New York State licensed drivers to determine the prevalence and circumstances of drowsy driving. Based on the survey responses, 54.6% of the drivers had driven while drowsy within the past year; 22.6% had ever fallen asleep at the wheel without having a crash, 2.8% had ever crashed when they fell asleep, and 1.9% had crashed when driving while drowsy. Of the reported crashes due to driving while drowsy or falling asleep at the wheel, 82.5% involved the driver alone in the vehicle, 60.0% occurred between 11:00 p.m. and 7:00 a.m. 47.5% were drive-off-road crashes, and 40.0% occurred on a highway or expressway. Multiple regression analysis suggested that the following driver variables are predictive of an increased frequency of driving drowsy: demographic characteristics (younger drivers, more education, and men); sleep patterns (fewer hours of sleep at night and greater frequency of trouble staying awake during the day); work patterns (greater frequency of driving for job and working rotating shifts); and driving patterns (greater number of miles driven annually and fewer number of hours a person can drive before becoming drowsy).     

Epidemiological aspects of inflammatory bowel disease in a north Italian population: a 4-year prospective study

OBJECTIVE: To determine the incidence and clinical characteristics at presentation of inflammatory bowel disease (IBD) in a defined area of north Italy. DESIGN: A 4-year prospective population-based epidemiological study. SETTING: An area in Lombardia defined by the National Health Service scheme with about 294,000 inhabitants, two referral hospitals and 259 general practitioners (GPs). PATIENTS: Subjects presenting to a GP with symptoms compatible with IBD underwent a diagnostic work-up at one of the referral hospitals. Those with ulcerative colitis (UC), Crohn's disease (CD) or indeterminate colitis diagnosed according to a defined protocol were included, as were residents of the area with IBD diagnosed elsewhere. Rigid case ascertainment methods were used. Patients were followed for one year; 125 patients were identified. RESULTS: The patient ascertainment rate was constant over the 4 years; UC was diagnosed in 82 patients, CD in 40, and indeterminate colitis in three. The mean annual incidence of IBD for the whole period was 10.6/10(5) inhabitants (95% confidence limits, 7.2-15.1), 7.0/10(5) for UC (4.3-10.7) and 3.4/10(5) (1.6-6.3) for CD. The mean interval between onset of symptoms and diagnosis was under 6 months. The clinical characteristics of our patients were similar to those of north European and American series. CONCLUSION: The incidence of IBD was higher than previously observed in Italy but was still lower than in some north European countries and in the USA. Our data could be used as a basis for future longitudinal studies and in international comparative investigations.     

Selective enumeration of Bacteroides vulgatus and B. distasonis organisms in the predominant human fecal flora by using monoclonal antibodies

The genus Bacteroides represents about one-third of the isolates from human fecal samples. The proportions of the different species are difficult to estimate because there is no method for rapid identification of mixtures of anaerobes. Monoclonal antibodies against Bacteroides vulgatus and B. distasonis were prepared. They did not react with the other Bacteroides species of the B. fragilis group. These reagents allowed direct enumeration of B. vulgatus and B. diastasonis organisms in human fecal samples. Anaerobic bacteria resistant to 1-h contact with air were enumerated in fecal human samples, a filter was layered on the colonies, and then B. vulgatus colonies were identified by an immunoassay performed with the prepared monoclonal antibodies. Healthy human adult volunteers were tested. Most of them harbored B. vulgatus at high levels, while the B. distasonis levels were always lower. Kinetic studies suggested that time variations for each volunteer were small. The simplified quantification of Bacteroides strains at the species level described here will prove useful in complementing our knowledge of the factors which may influence the predominant human fecal flora.     

Metabolic responses of the neonatal rabbit brain to hydrocephalus and shunting

The metabolic changes that occur in the neonatal brain as a result of hydrocephalus, and the response to ventriculoperitoneal shunting, vary with the maturational stage of the brain. In this study, local glucose utilization (LCMRglu) and oxidative metabolic capacity were estimated using 2-deoxyglucose autoradiography and cytochrome oxidase histochemistry, respectively. Hydrocephalus was induced in rabbit pups via intracisternal kaolin injections at 4-6 days of age. Shunting occurred at 19-26 days of age and the animals were sacrificed at ages ranging from 33 to 331 days. In normal animals there was a high glucose demand early in life which showed a decrease at about 60 days of age. In rabbits sacrificed prior to 60 days of age the controls showed the highest LCMRglu with significant decreases in both the hydrocephalic and shunted animals. After 60 days of age the shunted animals had higher LCMRglu than both the hydrocephalic and control subjects. Oxidative metabolic capacity peaked before 50 days of age in normal animals. At the youngest age, both the hydrocephalic and shunted animals showed higher cytochrome oxidase density rates than the control rabbits. In the older group, the hydrocephalic animals remained high while the shunted animals approximated the control densities. Neither the changes seen in the LCMRglu nor the oxidative metabolic capacity were correlated with changes in cell packing density or increased intracranial pressure. These data suggest that when the brain is compromised by hydrocephalus, there is an initial compensatory increase in oxidative metabolic capacity. The development of the glycolytic pathway appears to be retarded by hydrocephalus, but with shunting and the passage of time, the LCMRglu rebounds to levels above that of controls.     

Convenient colorimetric and fluorometric assays for S-nitrosothiols

S-nitrosothiols have been shown to affect a number of physiological functions. Several techniques have been used to detect these species in biological systems, primarily by methods utilizing chemiluminescence. Since the apparatus required for measurement of chemiluminescence are not readily available in most laboratories, methods employing more conventional techniques such as uv-vis and fluorescence spectroscopy may be of greater use. Herein, we report the development of colorimetric and fluorometric methods for the reliable quantitation of S-nitrosothiols. Solutions containing sulfanilamide/N-(1-naphthyl)- ethylenediamine dihydrochloride or 2,2'-azinobis (3-ethylbenzthiazoline-6-sulfonic acid), when exposed to S-nitrosoglutathione (GSNO), S-nitrosocysteine, or S-nitrosoacteylpenicillamine, resulted in no absorbance changes in the range of 400-800 nm. Exposure to HgCl2 or Cu(acetate)2 resulted in release of nitric oxide (NO) from the S-nitrosothiols. The liberated NO reacted subsequently with oxygen and formed a chemical species which reacted with either analysis solution, resulting in an increase in absorption between 400 and 800 nm. A plot of RSNO versus absorbance was linear for both mercury(II) and copper(II) ions where the slope in the presence of mercury ion was significantly greater than that for copper ion. The sensitivity was as low as 5 microM RSNO using HgCl2. The fluorometric method using 2, 3-diaminonaphthalene as the scavenger of the NOsolidusO2 products gave a sensitivity of 50 nM for GSNO. In addition, S-nitrosylated proteins were quantitated using the fluorometric technique. These methods provide accurate determination of low concentrations of S-nitrosothiols, utilizing conventional spectroscopic techniques available in most laboratories.