Calcium-binding proteins: the search for functions.
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Animals↗
Biomedical subjects
J Rogers
Publications and source records attributed to J Rogers.
Substrate specificity for interfacial catalysis by phospholipase A2 in the scooting mode.
Action of pig pancreatic phospholipase A2 on vesicles and micelles of homologous anionic phospholipids is examined in the absence of additives. As shown elsewhere (Jain et al. (1986) Biochim. Biophys. Acta 860, 435-447), hydrolysis of anionic vesicles occurs by interfacial catalysis in the scooting mode, i.e., the catalytic turnover is fast relative to the off-rate of the enzyme from the interface. When the rate of intervesicle exchange of the enzyme is negligibly slow, it hydrolyses only the substrate molecules in the outer monolayer of the vesicle to which it is bound. Interfacial catalysis in the scooting mode with a high processivity occurs on vesicles of anionic phospholipids, and under these conditions the dynamics and order of the substrate in the interface influences the catalytic turnover only moderately, i.e., about 2- to 10-fold. Similarly, anomalous kinetic effects of the thermotropic gel-fluid phase transition or of a change in the general disorder of the bilayer organization (fluidity) has a minor effect on the kinetics of hydrolysis in the scooting mode. Similarly, higher unsaturation and shorter acyl chains in the substrate modestly increase the rate of catalytic turnover by the low-calcium form of the enzyme without noticeably influencing the affinity of the enzyme for the interface. On the other hand, perturbation of the charge distribution in the substrate interface can shift the proportion of the bound enzyme by several orders of magnitude. For example, the membrane perturbing amphiphiles (e.g., mepacrine, indomethacin, compound 48/80, aristolochic acid, local anesthetics, and the products of hydrolysis) do not influence the catalytic turnover of the bound enzyme but the proportion of the bound enzyme. Short-chain anionic phospholipids are readily hydrolyzed by phospholipase A2. Now no anomalous increase in the rate of hydrolysis is observed at the critical micelle as is the case with the zwitterionic analogs. This is because with anionic (but not with zwitterionic) substrates the enzyme forms an aggregated complex below the cmc of the monomer. The stability of these micellar complexes does not appear to change noticeably with the acyl chain length of the monomers. These observations show that the factors regulating the quality of interface substantially influence the binding of the enzyme, but not the catalytic turnover in the interface.
Animals↗
Diagonal band projection towards the hypothalamic supraoptic nucleus: light and electron microscopic observations in the rat.
Supraoptic nucleus (SON) neurons receive a prominent gamma-amino-butyric acid (GABA) input. This study evaluated the hypothesis, partly on the basis of recent electrophysiological data, that this innervation might arise from GABAergic neurons located in the ventral diagonal band of Broca area. For retrograde transport studies, pentobarbital-anesthetized male Long-Evans rats received 0.03-0.20-microliter injections of a suspension of rhodamine tagged latex microspheres into the SON. In two cases where such injections were confined to the SON, less than 60 retrogradely labeled neurons were detected in the ipsilateral diagonal band. In three animals where injections extended into the perinuclear zone around the SON, more than 2,000 retrogradely labeled cells were counted in the ipsilateral diagonal band. For anterograde transport studies, another group of animals received either 30% horseradish peroxidase (HRP) in 0.5% poly-L-ornithine (0.05-0.10 microliter injections) or Phaseolus vulgarus (iontophoresed from a 2% solution) into the diagonal band. After survivals of 18-24 hours (HRP) or 5 days (PHAL-L) labeled axon terminals invested the perinuclear zone above the SON. The presence of just a single fiber within the nucleus indicated a minor projection to the SON itself. The HRP-injected material was processed for ultrastructural examination and revealed dense HRP-labeled axon terminals in this perinuclear zone, most often (98%) forming axodendritic appositions. A postembedding colloidal gold technique to visualize GABA-synthesizing terminals revealed that fewer than 5% of these perinuclear HRP-labeled terminals also exhibited GABA-like immunoreactivity. Within the SON, where GABAergic axon terminals are abundant, few (less than 5%) GABAergic terminals contained HRP.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Anorectal physiology validated: a repeatability study of the motor and sensory tests of anorectal function.
Sixteen subjects (mean (s.d.) age 50.7 (12.8) years, three men) were studied on two separate occasions by two experienced investigators in random order. A standard protocol of anatomical, manometric and electrophysiological assessments of anorectal motor and sensory function was followed. No significant differences were found between the results obtained by the two investigators in the measurements of perineal descent, anal canal length, and canal resting pressure and squeeze pressure, pudendal nerve terminal motor latency, single-fibre electromyography fibre density of the external anal sphincter, and thresholds of mucosal electrosensitivity. This study shows that the standard tests of anorectal sensorimotor function are repeatable by different investigators. In addition, it suggests that comparison of data obtained in different centres using these techniques is valid.
Adult↗
Calbindin-D28 in mammalian brain, retina, and endocrine pancreas: immunohistochemical comparison with calretinin.
Calbindin 28K and calretinin are very similar calcium binding proteins which are both present in the central nervous system (CNS). They respectively bind 4 and 5 Ca++ ions. We have compared by immunohistochemistry and in situ hybridization their localisation in the brain and the retina. The two proteins are generally expressed in different neurons with a few neurons containing both calcium binding proteins. Calbindin 28K is also present in the endocrine system. We have examined the cellular distribution of calbindin in the pancreatic endocrine cells of chick, rat and human and found variable distribution among the different endocrine cell types. We also describe the presence of calbindin in RINm5F cells, an insulin-producing tumor cell line derived from a radiation-induced rat insulinoma.
Animals↗
Centromeric alpha satellite DNA amplification and translocation in an unusually large chromosome 14p+ variant.
We report cytogenetic and molecular studies on a family that carries, in the father, an unusually large chromosome 14p+ variant [WSi-var(14)(p+)] and, in one of his children, a translocation [DSi-der(14)] involving the variant chromosome. Increase in the size of WSi-var(14)(p+) was estimated to be approximately 35% that of a normal chromosome 14. Presence of extra chromosomal material in this variant chromosome was demonstrated by G-banding using trypsin and staining with Leishman, G-banding using bromodeoxyuridine (BrdU) and Giemsa, and R-banding using BrdU and Giemsa. This material was positive using C-banding with BaOH and staining with Giemsa and negative in DAPI/distamycin staining, suggesting that it contained repetitive DNA but probably not of the types found in the heterochromatic regions of chromosomes 1, 9, 15, 16, and Y. Staining of the nucleolus organiser region (NOR) with AgNO3 indicated the retention of the NOR in WSi-var(14)(p+) but not in DSi-der(14). In situ hybridisation of metaphase cells with an alpha satellite DNA probe specific for human acrocentric chromosomes demonstrated a significantly increased amount of centromeric alpha sequences in WSi-var(14)(p+). Most or all of the extra alpha sequences were retained in DSi-der(14), indicating translocation near the very distal end of the enlarged region. The extra alpha satellite DNA material may have originated through amplification of some centromeric segments. The possible role of the amplified DNA in chromosomal translocations is discussed.
Chromosome Banding↗
Familial transmission of 16p trisomy in an infant.
Based on four reported cases including the present case, 16p trisomic infants have remarkably similar features. These are severe developmental delay, psychomotor retardation, typical facies, and anomalies of extremities.
Chromosome Banding↗
A specific interaction in vitro between pancreatic zymogen granules and plasma membranes: stimulation by G-protein activators but not by Ca2+.
The molecular details of the final step in the process of regulated exocytosis, the fusion of the membrane of the secretory granule with the plasma membrane, are at present obscure. As a first step in an investigation of this membrane fusion event, we have developed a cell-free assay for the interaction between pancreatic zymogen granules and plasma membranes. We show here that plasma membranes are able to trigger the release of the granule contents, and that this effect is specific to pancreatic membranes, involves membrane fusion, requires membrane proteins, and is stimulated by activators of G-proteins but not by Ca2+. The assay is simple, reliable, and rapid, and should permit the identification of proteins that are involved in the exocytotic fusion event.
Animals↗
Prevalence of antibodies to SIV in baboons in their native habitat.
We have documented rare infection of baboons in their native habitat with simian immunodeficiency virus (SIV). Of 124 sera collected from yellow baboons in central Tanzania, two gave high readings by SIVagm ELISA (greater than 1.0) and moderate by SIVmac ELISA (0.5-1.0). These two sera gave strong reactions to the major SIVagm proteins, including gp130, by western blot analysis; their reactivity to SIVmac protein was considerably weaker. Similar testing of 155 sera from olive baboons of Ethiopia revealed no clearly positive sera. Thus, 2 of 279 baboon sera or 0.7% were positive for antibodies to SIV. The strong reactivity of the two positive yellow baboon sera with SIVagm proteins raises questions about whether these animals may have been infected by green monkeys in their native habitat; baboons occasionally prey upon and eat green monkeys. In addition to these two clearly positive samples, one olive baboon serum and one yellow baboon serum reacted only with major gag protein (p24-p26). Continued study of prevalence and diversity of SIV in primates will be important for understanding the history and evolution of primate lentiviruses and, it is hoped, the origins of viruses that cause AIDS in humans.
Animals↗
The management of pseudohypacusis in school-age children.
Pseudohypacusis is a condition in which there is an apparent hearing loss in the absence of clinical or audiological evidence; indeed, audiological assessment for inconsistencies is the mainstay of diagnosis. It is easier to diagnose in children than in adults, due to a child's inability to produce consistently similar results on repeat tests. We have reviewed 15 children with pseudohypacusis, who had an average loss in the right ear of 57 dB, and of 59 dB in the left ear when tested by pure tone audiometry. Eight children were diagnosed by clinical impression and inconsistent pure tone audiograms but in order to confirm the diagnosis in the other seven children further testing with a speech audiogram was necessary and proved sufficient to establish the diagnosis in all cases. The hearing of all 15 children resolved spontaneously at between 2 and 70 months, when treated by careful monitoring and supportive therapy, and none of the children needed psychiatric referral.
Audiometry, Pure-Tone↗
Increased segmental activity and intraluminal pressures in the sigmoid colon of patients with the irritable bowel syndrome.
Intraluminal pressure activity has been recorded in the unprepared true sigmoid colon of seven normal controls (mean age 37 years, range 22-55, three men) and seven patients with irritable bowel syndrome (IBS) (45 years, 24-75, four men) for 30 minutes before and 100 minutes after a standard 1000 kcal meal. Results differ from previously published data by showing much higher indices of pressure activity with amplitudes up to 490 mmHg in IBS, and 450 mmHg in controls. Study segment activity index and mean pressure wave amplitudes were significantly (p less than 0.015 and p less than 0.01) higher in IBS than controls, but per cent duration of activity was similar for the whole period of study. During the basal period in controls mean amplitudes recorded from the proximal sigmoid (40 cm from anus) were significantly (p less than 0.01) higher than those in the descending colon (50 cm), distal sigmoid (30 cm) and rectum (15 cm). This study shows that the increased colonic activity in IBS is characterised by increased amplitude, but not duration of pressure waves. In the basal state there is a high pressure zone in the proximal sigmoid colon of controls. Pressures in the unprepared colon of controls and IBS were higher than those measured under other experimental conditions.
Adult↗
Fully automated computer analysis of intracolonic pressures.
A fully automated (PC compatible) software and hardware analysis system has been designed and developed to analyse colonic pressure records quickly and objectively. Eight hours of colonic pressure trace was analysed in 48 10 minute epochs manually and by computer for the variables of mean amplitude, % duration of activity, motility index, number of peaks and activity index. Agreement between methods was good for mean amplitude: (bias -0.5 mmHg; (36.8) (2 SD, limits of agreement); -5.8 to 4.8, 95% CI of bias; 0-289, average range of values by both methods), % duration of activity: (-0.9; (13.4); -2.9 to 0.9; 0-100), motility index: (-55; (2072); -356 to 245; 0-26,220), number of peaks: (-20; (91); -44 to 3.5; 1-211), and activity index bias -5.2 mmHg. min; (127.3); -23.7, to 13.2; 0-2159. The time taken for manual analysis was 889 minutes compared with 14 minutes for the automated system. Fully automated analysis of colonic pressure records is fast, objective, and shows good agreement with labour intensive manual analysis. Previously acquired data can be reanalysed using new definitions and criteria. Widespread use of the technique could introduce uniformity in colonic pressure record analysis. In addition this wave form analysis system can be adapted to record and analyse pressure data from other regions of the gastrointestinal tract.
Colon↗
Correlation of clinical and molecular biological abnormalities in osteogenesis imperfecta.
Substitution of a glycine residue in the triple helix of the alpha 1(I) chain by either arginine, valine or alanine was associated with the type II lethal perinatal osteogenesis imperfecta phenotype. This phenotype was also produced by a frameshift mutation that resulted in an abnormal amino acid sequence of the carboxy-terminal propeptide of the pro-alpha 1(I) chain. The latter baby, however, showed some clinical and radiographic differences from the other babies with type II OI. The severity of the clinical and radiographic phenotypes are likely to be determined by both the type and site of the mutation as well as by the intra-uterine environment.
Alanine↗
Prolene plug repair for femoral hernia.
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Follow-Up Studies↗
Acute urinary retention: which catheter?
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Humans↗
Infarction of the superior temporal gyrus: a description of auditory evoked potential latency and amplitude topology.
P1 and N1 of the cortical auditory evoked potential (AEP) were studied with multiple electrodes in 10 normal subjects and 6 patients with left middle cerebral artery infarction. Patients were selected based on neurological examination and on CT scans showing both (1) infarction limited to the vascular territory and (2) involvement of posterior portion of superior temporal gyrus. Waveforms recorded from C3, Cz, and C4 were examined for peak latency and amplitude of P1 and N1 on all subjects. Topographic displays of amplitude over P1 and N1 latency ranges were also examined. In normals, P1 was identified in 9 of the 10 subjects at all three electrode sites. In patients, P1 was identified at C3 in only 1 of the 6. N1 was present at all three electrodes in the 10 normal subjects and in 5 of the 6 patients. The remaining patient had N1 at C4 and Cz only. Examination of amplitude topology showed as asymmetric evolution of P1 and N1 in the patients. This asymmetry was not present in normals. The results of this study are consistent with theory that P1 arises from primary auditory cortex. Results further suggest multiple generators for N1. Additional study correlating topographic display from multichannel recordings with CT or MRI in brain-injured patients may bring more insight into N1 generators.
Adult↗
Effect of diet on [lactate]/[pyruvate] ratios during alcohol metabolism in man.
Ten subjects received alcohol by intravenous infusion on two occasions, after five-day periods on high- or low-carbohydrate diets. Blood [lactate]/[pyruvate] ratios were significantly higher during fasting alcohol metabolism after the low-carbohydrate, high-fat diet. The carbohydrate/fat balance in the diet may affect cytoplasmic-mitochondrial NADH transfer. Dietary composition may modify the metabolic changes caused by alcohol.
Adult↗
Immune system associated antigens expressed by cells of the human central nervous system.
HLA-DR, HLA-DQ and HLA-DP are class II major histocompatibility complex (MHC) antigens necessary for T cell binding and antigen presentation. Interleukin-2 is a lymphokine used by the immune system to signal proliferation of cells in the immune response. Using unfixed tissue and free-floating immunohistochemistry, we show profuse immunoreactivity for these immune antigens in white and gray matter samples from normal and Alzheimer's (AD) disease patients. On morphologic grounds, immunoreactive cell types appear to include astrocytes, microglia, macrophages, and endothelial cells or pericytes.
Adult↗