Detection of somatic mutations in man: evaluation of the microtitre cloning assay for T-lymphocytes

A method of detecting 6-thioguanine-resistant lymphocytes bythe cloning of T-lymphocytes in microtitre wells is evaluatedfor its usefulness in population monitoring. Factors shown toaffect the cloning efficiency of lymphocytes include the strainand irradiation level of the lymphoblastoid feeder cells andthe use of a pre-incubation period in bulk culture without mitogenicstimulus before plating at limiting dilutions. Cord blood sampleshave markedly lower mutant frequencies than adult blood samples.The adult range was 8.0 x 10^–7 to 1.8 x 10^–5. Sevenmales and seven females aged between 23 and 47 years were sampled.No effect of sex or age was found. Individual samples whichwere divided at collection and treated separately did not varyfrom each other, but repeat samples taken at different timesshowd up to a 2-fold variation. The application of this methodin population monitoring is discussed.     

Brain responses associated with the Valsalva maneuver revealed by functional magnetic resonance imaging

The Valsalva maneuver, a test frequently used to evaluate autonomic function, recruits discrete neural sites. The time courses of neural recruitment relative to accompanying cardiovascular and breathing patterns are unknown. We examined functional magnetic resonance imaging signal changes within the brain to repeated Valsalva maneuvers and correlated these changes with physiological trends. In 12 healthy subjects (age, 30-58 yr), a series of 25 volumes (20 gradient echo echo-planar image slices per volume) was collected using a 1.5-Tesla scanner during a 60-s baseline and 90-s challenge period consisting of three Valsalva maneuvers. Regions of interest were examined for signal intensity changes over baseline and challenge conditions in cardiorespiratory-related regions. In addition, whole brain correlations between signal intensity and heart rate and airway load pressure were performed on a voxel-by-voxel basis. Significant signal changes, correlated with the time course of load pressure and heart rate, emerged within multiple areas, including the amygdala and hippocampus, insular and lateral frontal cortices, dorsal pons, dorsal medulla, lentiform nucleus, and fastigial and dentate nuclei of the cerebellum. Signal intensities peaked early in the Valsalva maneuver within the hippocampus and amygdala, later within the dorsal medulla, pons and midbrain, and deep cerebellar nuclei, and last within the lentiform nuclei and the lateral prefrontal cortex. The ventral pontine signals increased during the challenge, but not in a fashion correlated to load pressure or heart rate. Sites showing little or no correlation included the vermis and medial prefrontal cortex. These data suggest an initiating component arising in rostral brain areas, a later contribution from cerebellar nuclei, basal ganglia, and lateral prefrontal cortex, and a role for the ventral pons in mediating longer term processes.     

Genetic and environmental determinants of the lability of trait neuroticism and the symptoms of anxiety and depression

A genetic analysis was conducted on trait neuroticism and symptoms of anxiety and depression in a five-wave study of 462 twin pairs. Models that assessed the relative importance of genetic and environmental factors to the lability (within-individual variability over time) of these measures were fitted to the data. Previous results concerning the substantial genetic involvement in the level of neuroticism and symptoms were confirmed. However, it was found that neither genes nor the shared environment of the twins was a significant cause of lability of these measures. An attempt was therefore made to identify aspects of individuals' environments that might be responsible for lability of neuroticism and symptoms. Adverse life events were found to predict variability of symptoms, but not of neuroticism. The availability of close social ties or having affectionless control in childhood did not contribute to lability.     

Molecular weights of individual proteins correlate with molecular volumes measured by atomic force microscopy

 Proteins are usually identified by their molecular weights, and atomic force microscopy (AFM) produces images of single molecules in three dimensions. We have used AFM to measure the molecular volumes of a number of proteins and to determine any correlation with their known molecular weights. We used native proteins (the TATA-binding protein Tbp, a fusion protein of glutathione-S-transferase and the renal potassium channel protein ROMK1, the immunoglobulins IgG and IgM, and the vasodilator-stimulated phosphoprotein VASP) and also denatured proteins (the red blood cell proteins actin, Band 3 and spectrin separated by SDS-gel electrophoresis and isolated from nitrocellulose). Proteins studied had molecular weights between 38 and 900 kDa and were imaged attached to a mica substrate. We found that molecular weight increased with an increasing molecular volume (correlation coefficient = 0.994). Thus, the molecular volumes measured with AFM compare well with the calculated volumes of the individual proteins. The degree of resolution achieved (lateral 5 nm, vertical 0.2 nm) depended upon the firm attachment of the proteins to the mica. This was aided by coating the mica with suitable detergent and by imaging using the AFM tapping mode which minimizes any lateral force applied to the protein. We conclude that single (native and denatured) proteins can be imaged by AFM in three dimensions and identified by their specific molecular volumes. This new approach permits detection of the number of monomers of a homomultimeric protein and study of single proteins under physiological conditions at the molecular level. Received: 14 February 1997 / Received after revision: 8 September 1997 / Accepted: 8 September 1997     

Endoscopic sphincterotomy in the management of benign and malignant extrahepatic biliary obstruction

One hundred twenty-one patients with extrahepatic biliary obstruction underwent endoscopic sphincterotomy (EST). This was followed by balloon occlusion catheter or dormia basket stone extraction in 106 patients with choledocholithiasis, and by transpapillary biliary endoprosthesis placement in 15 patients with malignant distal common bile duct obstruction. All patients had excellent biliary decompression. Complications not requiring surgical intervention were seen in six patients. This article shows that EST is a low-risk, effective therapy for benign and malignant extrahepatic biliary obstruction.     

Pharmacokinetics of clavulanic acid-potentiated ticarcillin in renal failure

The serum kinetics of an intravenous bolus of a combination of ticarcillin (TIC) (3 g) and clavulanic acid (CLAV) (0.2 g) have been determined in a number of patients with different degrees of renal failure as characterized by creatinine clearance. The volume of distribution for both drugs was unaffected by renal failure. Indices of serum and renal drug clearance were related to the degree of renal failure. TIC was cleared more slowly than CLAV. Anephric patients may have a higher serum clearance of CLAV than patients categorized by creatinine clearance as having severe renal failure; this could be due to an increase in metabolic clearance. Haemodialysis effectively clears both drugs. "Rebound" serum concentrations were consistently observed for TIC, but were observed in only one patient for CLAV. Continuous ambulatory peritoneal dialysis results in significant recovery of both drugs. The dosing requirements for the combination of TIC and CLAV in patients with renal failure are considered.     

Cancer of the gastrointestinal tract among Japanese and white immigrants in Los Angeles County

With the use of age-adjusted incidence rates and proportional incidence ratios, investigators studied the risk of cancer of the stomach and 3 subdivisions of the large bowel in three race-ethnic groups--Spanish surnamed whites, other whites, and Japanese--and compared Los Angeles County native residents, immigrants, and representative "homeland" populations. The risk pattern for each of the four anatomic sites was quite distinctive, suggesting at least four different etiologic complexes. For each site the observed gradients of risk are nearly identical for each sex, usually with risk for immigrants intermediary between that for homeland residents and that for local natives; the differences between race-ethnic groups are consistent with known international patterns. Particularly notable is the contrast between the low risks of cancer of both the sigmoid and the rectum in Japan and the high risks for Japanese immigrants to Los Angeles, which are nearly double those of their U.S. white neighbors. In all instances, and especially for both the upper and lower colon, the influence of the adult environment predominates over that of the early environment. The environmental determinants of stomach cancer do not always appear in inverse correlation with those of colon cancer, since Japanese immigrants to Los Angeles and their descendants are at high absolute and relative risk of both neoplasms. Our findings suggest that patterns of risk in relation to migration are complex and defy simple dietary or other interpretation. Without more information about the impact of migration to the United States on qualitative and quantitative aspects of lifestyle, it is not possible to put forward simple hypotheses that explain all available facts.     

Cyclophosphamide, vincristine, adriamycin, and prednisone (CHOP) with and without intermediate dose methotrexate for the treatment of non-Hodgkin's lymphomas of diffuse histology

Seventy three patients with disseminated diffuse non-Hodgkin's lymphomas were treated with combinations of cyclophosphamide, vincristine sulfate, prednisone, and doxorubicin with and without 2 weekly doses of oral methotrexate in "intermediate" doses, followed by calcium leucovorin rescue. The addition of methotrexate did not increase the complete remission rate, the remission duration, or the survival (P value = 1.0, 0.74, and 0.78, respectively) in patients who did not have previous chemotherapy treatment. In previously treated patients, the complete remission rate was somewhat higher and the remission duration and survival were longer among those patients treated with the methotrexate containing program; however these differences were not statistically significant (P values = 0.88, 0.81, and 0.46, respectively). There was substantial morbidity and mortality during treatment with both treatment arms, among patients aged more than 60 years.     

“Making Room”: A Thematic Analysis Study of the Process of Postpartum Maternal Adjustment

Maternal and Child Health Journal - Mothers are especially vulnerable to the onset or recurrence of psychological symptoms during the postpartum period. However, protective psychosocial factors may...