bcl-2 transgene expression inhibits apoptosis in the germinal center and reveals differences in the selection of memory B cells and bone marrow antibody-forming cells.

Immunization with T cell-dependent antigens generates long-lived memory B cells and antibody-forming cells (AFCs). Both populations originate in germinal centers and, predominantly, produce antibodies with high affinity for antigen. The means by which germinal center B cells are recruited into these populations remains unclear. We have examined affinity maturation of antigen-specific B cells in mice expressing the cell death inhibitor bcl-2 as a transgene. Such mice had reduced apoptosis in germinal centers and an excessive number of memory B cells with a low frequency of V gene somatic mutation, including those mutations encoding amino acid exchanges known to enhance affinity. Despite the frequency of AFCs being increased in bcl-2-transgenic mice, the fraction secreting high-affinity antibody in the bone marrow at day 42 remained unchanged compared with controls. The inability of BCL-2 to alter selection of bone marrow AFCs is consistent with these cells being selected within the germinal center on the basis of their affinity being above some threshold rather than their survival being due to a selective competition for an antigen-based signal. Continuous competition for antigen does, however, explain formation of the memory compartment.

Single-dose and steady-state effects of controlled-release salbutamol on drug level and airflow obstruction in patients with asthma.

Oral medication remains the mainstay of treatment for many asthmatics. We compared the single dose and steady-state effects of twice daily 4 mg and 8 mg controlled-release salbutamol (CRS) on plasma salbutamol and FEV1 in 10 asthmatic patients in a double-blind, double-dummy, cross-over study. On 5 separate days, one week apart, we measured FEV1 and plasma salbutamol hourly for 12 hours after a single dose and, after twice daily doses (4 mg, 8 mg or placebo CRS) for one week. Controlled-release salbutamol showed controlled release properties and dose effect for the two doses. At steady-state, it provided relatively constant plasma levels for 12 hours. Significant and similar bronchodilatation occurred after both 4 mg and 8 mg CRS taken either as a single dose or a steady-state regime.

Excessive bronchoconstriction induced by histamine and effects of volume history in patients with bronchial asthma.

The aim of this study was to examine the inter-relationships between the different effects of deep breaths and histamine provocation on airway function in patients with bronchial asthma. Group 1 consisted of 38 consecutive out-patients with newly diagnosed mild asthma, group 2 consisted of 20 patients with bronchial asthma of varying severity who were studied during clinical remission. We measured bronchial responsiveness (BR) to histamine inhalation as the dose of histamine which provoked a 20% fall in FEV1 (PD20). The fall in forced vital capacity (FVC) after inhaling the highest dose of histamine during each BR test was calculated and expressed as percentage of the value measured at baseline (delta FVC in percentage). We studied the effects of deep breaths on airway caliber in group 2 patients by comparing isovolumic flow rates on partial (P) and maximal (M) forced expiratory flow volumes curves expressed as the M/P ratio. The changes in residual volume (RV) after deep breaths (delta RV) were expressed as a percentage of the largest VC measured on the composite M and P curves. The patients in group 1 had significantly higher PD20 and lower delta FVC than patients in group 2. There was, however, no significant correlation between PD20 and delta FVC measurements in individual patients (r < 0.1, P > 0.05). The M/P ratio was significantly related to delta FVC (r = -0.6, P < 0.006). There was also a significant positive relation between the magnitude of increase in residual volume following deep breaths (delta RV) and the degree of fall in FVC following histamine inhalation (delta FVC) (r = 0.65, P = 0.001). This significant relationship between the degree of airway closure after a deep breath and airway closure after histamine challenge is a new finding. In patients with bronchial asthma, the effects of a deep breath on airway function may be indicative of the tendency for airway closure during BR testing.

Labeled lectin studies of renal tubular dysgenesis and renal tubular atrophy of postnatal renal ischemia and end-stage kidney disease.

Renal tubular dysgenesis (RTD), with hypoplasia especially of renal proximal convoluted tubules and clinical neonatal anuria or oliguria, has been reported as a congenital familial (autosomal recessive) disease, variably with features of oligohydramnios, Potter syndrome, or pulmonary hypoplasia. A similar tubular lesion due to antenatal tubular atrophy has been reported for conjoined twins with twin-twin transfusion syndrome or acardia and in infants of mothers given antihypertensive agents, including angiotensin-converting enzyme (ACE) inhibitors, during pregnancy, and it has been seen as a unilateral lesion in young infants with renal artery stenosis due to arteritis or medial arterial calcinosis. The renal tubular changes in RTD are very like those of the "endocrine kidney" in experimental animals and resemble those of the renal tubular atrophy of end-stage kidney diseases such as glomerulonephritis, tubulointerstitial kidney disease, obstructive uropathy/pyelonephritis, graft rejection of transplanted kidneys, or the renal parenchymal changes seen with protracted dialysis therapy. Labeled lectins that differentially mark proximal convoluted, distal convoluted and connecting, and collecting tubules showed no distinctive differences in staining patterns of the hypoplastic renal tubules of infants and children with RTD, postnatal renal artery obstruction, or the various types of end-stage renal disease with the lectins used (PNA, GSLI, UEA, and LTA). The findings suggest that the renal tubular changes in some if not all the conditions studied are the result of renal ischemia. The reported familial RTD with hypernephronic nephromegaly may be a specific disorder, but other forms could reflect renal ischemia acquired in utero or in early or later postnatal life.

Studies of the enteric nervous system in Alzheimer disease and other dementias of the elderly: enteric neurons in Alzheimer disease.

Studies of the myenteric (Auerbach) plexus of esophagus, stomach, small intestine, colon, and rectum, by microdissection and pointcount morphometry, for 18 patients with Alzheimer disease (AD), eight with other types of dementia of the elderly, non-demented elderly patients, and younger control patients, show a normal loss of enteric neurons and plexus mass with age, comparable to that reported by others for rats and guinea pigs. Values for patients with AD or other non-AD dementias did not differ from those for elderly controls. Enteric neurons in AD or the other dementias studied showed no definite stain with ALZ-50, a monoclonal antibody to a derivative of the microtubule-associated protein tau, which stains degenerating cerebral neurons in AD. Although the processes in the central nervous system in AD affect some neurons derived from the neural plate, the results of this study suggest that the enteric neurons, which are of neural crest origin, are not affected in AD. Enteric neurons, at least by the methods of this study, do not provide a useful peripheral marker for AD.

Microdissection study of the myenteric plexus in acardia, ataxia-telangiectasia, cystic fibrosis, extrahepatic biliary atresia, pediatric AIDS and Werdnig-Hoffmann disease.

Microdissection-point count morphometric study of the myenteric (Auerbach) plexus or esophagus, small intestine, and colon was done for infants and children with acardia (2), ataxia-telangiectasia (5), cystic fibrosis of the pancreas (CFP) (25), extrahepatic biliary atresia (EBA) (17), pediatric AIDS (10), and Werdnig-Hoffmann disease (WHD) (8). Values for fractional area of neural tissue in the plane of the plexus were compared to those of control patients in same age range as those in each disease category by t-test. Statistically abnormal values included low values for small intestine and colon in Werdnig-Hoffmann disease, high values for small intestine and colon in biliary atresia, and high value for colon but a low value for small intestine in cystic fibrosis. Values for all three loci were within the normal range for ataxia telangiectasia and pediatric AIDS. The mechanisms of the low value for small and large intestines in WHD, which causes chronic constipation as a result of skeletal muscle weakness, and of the high values for colon in CFP and EBA, both causing malabsorption with bulky stools, are unclear. The value for small intestine in acardia was normal for term but lower than expected for fetal bowel of the same size, possibly because of reduced neural crest inflow to the fetal bowel.

The effects of deep inhalation on maximal expiratory flow during intensive treatment of spontaneous asthmatic episodes.

Asthmatic patients who came to hospital for treatment of severe attacks were assessed for level of obstruction and the effects of a deep inhalation (DI) on degree of obstruction at various stages of their treatment and after recovery over several days. The more severe the obstruction, the greater was the constrictor effect of a DI; as lung function improved with intensive treatment, including corticosteroids, the constrictor effect diminished. Thus, we believe the constrictor effects of a DI relate to the degree of inflammation in the obstructive process. These longitudinal data relating severity to the effects of a DI were nearly identical to previously published cross-sectional data in a group of patients with spontaneous asthma with widely different levels of lung function. It is possible that the response to a DI in a given asthmatic subject serves as a functional marker for the predominant mechanism for obstruction.

Branching patterns of right pulmonary artery in cardiovascular anomalies.

The branch of the right pulmonary artery (RPA) to the upper lobe of the right lung (RUL), the truncus anterior of the RPA, and the pars anterior of the left pulmonary artery, which supplies the left upper lung lobe (LUL), were demonstrated by both dissection of postmortem specimens and angiography for 20 infants and children, by angiography only for 57, and by specimen dissection only for 59 (total 136). In posteroanterior angiograms, the RUL artery branches from the RPA near the right lateral border of the vertebral column, while the LUL artery or arteries arise more laterally, near the left midclavicular plane. This pattern is reversed in situs inversus (eight patients studied). Thirty-nine patients in other categories of congenital cardiovascular disease showed an abnormal RUL or LUL arterial pattern, including pulmonary isomerism, right lung type (RUL artery pattern present bilaterally, 12 patients); pulmonary isomerism, left lung type (RUL artery pattern absent bilaterally, 11 patients); scimitar syndrome (RUL artery pattern normal, 1 patient; absent bilaterally, 4 patients); and left pulmonary artery sling (RUL artery normal, one; hypoplastic, one; absent, two patients). Five patients with tetralogy of Fallot (TOF) with right aortic arch (RAA) and 1 of 15 with RAA not TOF or situs inversus showed a relatively large RUL artery arising more laterally than usual. Three of six patients with double outlet right ventricle had the LUL artery larger than usual plus two accessory RUL arteries, and one patient with crossed pulmonary arteries showed a similar pattern. Two patients with single ventricle had an RUL artery of normal pattern although the RUL bronchus was absent, and one patient with single ventricle and situs inversus had a comparable pattern in the left lung. The ease of demonstration of the right and left upper lobe branches of the pulmonary artery by dissection or angiocardiography warrants greater attention to their patterns in patients with congenital cardiovascular disease. Dissociation of upper lobe bronchial and vascular patterns is unusual and may also be of diagnostic value.