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Biomedical subjects

J Potter

Publications and source records attributed to J Potter.

At least 127 records · Page 7Linked to original sources
PubMed1986

Molecular cloning and sequence analysis of a haploid expressed gene encoding t complex polypeptide 1.

The mouse t haplotypes show defects in spermatogenesis attributed to multiple loci on chromosome 17. We have cloned the gene for an abundant testicular germ cell protein, t complex polypeptide 1, which has a variant form in t haplotypes, TCP-1A. A cDNA clone, pB1.4, which hybridizes to a 19S mRNA that is abundant in haploid cells during mouse spermatogenesis, derives from the 3' end of the mRNA encoding TCP-1B. The Tcp-1 gene appears to be a member of a novel gene family and shows multiple changes between the predicted amino acid sequences of TCP-1B and TCP-1A. An additional Taq1 site is created by a T to C transition in the predicted open reading frame of the Tcp-1a gene. The resultant RFLP has allowed typing of the Tcp-1 gene cluster in 54 complete and partial t haplotype chromosomes. DNA sequence comparison of the Tcp-1 genes suggests that the t haplotype chromosome arose within the genus Mus more than one million years ago.

Animals↗
PubMed1986

Mineral status of beef cattle in Papua New Guinea.

Groups of 22 steers grazed eight diverse environments in Papua New Guinea for one year. Haemoglobin, packed cell volume, MCHC, plasma albumen, calcium, magnesium, phosphorus, zinc, copper and saliva sodium and potassium were measured; half of each group received cobalt supplements. Growth rate was measured. Cobalt deficiency was tentatively diagnosed at two sites, sodium deficiency at five sites and phosphorus at three with two other sites marginal. Sodium supplementation at the three most affected sites corrected sodium status and increased growth rate. Additionally, at two of these sites plasma phosphorus concentration increased to more normal levels presumably due to increased appetite. Statistically significant differences between sites occurred in the concentrations of other minerals but were not related to growth rates. The significance of these results is discussed in relation to assessment of mineral status in beef cattle.

Animals↗
PubMed1986

Sensitivity in vivo of Plasmodium falciparum to chloroquine and pyrimethamine/sulfadoxine in a coastal area of Tanzania.

The in vivo response of Plasmodium falciparum to chloroquine and to pyrimethamine/sulfadoxine was studied for seven days in schoolchildren from two villages 30 to 40 km north of Dar es Salaam. Standard therapeutic regimen of chloroquine (25 mg base kg-1) failed to clear parasitaemia in 17 of 62 (27%) treated subjects. In contrast, standard treatment with pyrimethamine/sulfadoxine cleared the parasitaemia in all 44 treated subjects within five days. Hence, in the studied area, the therapeutic effect of sulfadoxine/pyrimethamine was superior to that of chloroquine.

Adolescent↗
PubMed1986

Motilin's induction of phasic contractility in canine jejunum is mediated by the luminal release of serotonin.

To determine whether mucosal serotonin (5-HT) is involved in the intestinal motility response to motilin, we studied the effects of intra-arterial infusions of motilin (5 X 10(-10) mol/L) in isolated, vascularly perfused segments of canine jejunum. Intraluminal pressures were continuously recorded through a perfused manometric catheter, and venous and luminal 5-HT levels were measured by radioimmunoassay. Luminal 5-HT output rose from a basal of 54 +/- 12 to a peak of 151 +/- 30 ng/min X 100 gm (p less than 0.01) with the motilin infusion. The earliest significant rise in luminal (5-HT), which occurred at 1 minute after the start of the motilin infusion, preceded the onset of phasic contractility. The rise in the motility index induced by motilin demonstrated a strong correlation (r = 0.72, p less than 0.01) with rises in luminal 5-HT output. 5-HT tachyphylaxis abolished the motility response to motilin; prior treatment with atropine abolished, while tetrodotoxin inhibited the luminal release of 5-HT. An infusion of exogenous 5-HT giving equivalent luminal 5-HT levels as induced by motilin led to similar phasic contractility and rise in the motility index. These findings suggest that motilin initiates phasic contractility in canine jejunum through the cholinergically mediated release of mucosal serotonin.

Animals↗
PubMed1985

Human lactase and the molecular basis of lactase persistence.

Human lactase purified from detergent extracts of the total membrane fraction of postmortem jejunum by means of monoclonal immunoadsorbent chromatography appears to be a dimer of subunits identical in Mr (160K). Trypsin or papain removes a small hydrophobic anchoring peptide from each subunit to give a hydrophilic enzyme which no longer interacts with detergent micelles. Lactase hydrolyzes, besides lactose, cellobiose and the synthetic substrates, 4-methylumbelliferyl-beta-galactoside and beta-glucoside, as well as phlorizin; but it does not hydrolyze glucocerebroside. Phlorizin hydrolase is associated with lactase under all conditions investigated; coincident staining on immunodiffusion and immunoelectrophoresis, coincident elution on immunoadsorbent chromatography and on gel filtration in a dissociating buffer, and correlated reduction in activity in lactase-nonpersistent individuals. Adult and infant lactases are indistinguishable by titration or immunodiffusion against polyclonal rabbit antibodies. Adult individuals low in lactase activity also show a corresponding reduction in cross-reacting material. These observations suggest that lactase persistence is due to the continued synthesis of the infant enzyme.

Antibodies, Monoclonal↗
PubMed1984

Masters of surgery.

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Education, Medical, Graduate↗
PubMed1984

Analysis of male sterile mutations in the mouse using haploid stage expressed cDNA probes.

A differential hybridization screening procedure has identified cDNAs which correspond to RNAs which are expressed in mouse testis and at lower levels in liver and spleen. The sensitivity of this procedure is such that approximately 0.5% of 1.4 X 10(4) cDNA clones are revealed as "testis specific". We have focused on ten cDNA clones which have been used to identify RNAs expressed in the haploid phase of spermatogenesis. Using Northern blots to analyse RNA isolated from the testes of mutant mice (Tfm/Y and Sxr/+) blocked at specific stages in spermatogenesis or RNA from sexually immature mice, 8 clones have been identified which correspond to RNAs expressed uniquely or at much higher levels in meiotic or post meiotic cells.

Animals↗
PubMed1984

Relationship between pyridoxal 5'-phosphate deficiency and aminotransferase levels in alcoholic hepatitis.

The relationship between pyridoxal phosphate deficiency and activities of serum and liver aminotransferases was studied in 12 patients with alcoholic hepatitis. Plasma pyridoxal phosphate and the activities of liver aminotransferases were initially decreased in the patients, as compared with mean values in controls with normal hepatic histology. Addition of pyridoxal phosphate to liver homogenates increased liver alanine aminotransferase, but not aspartate aminotransferase, in all patients with initially low plasma pyridoxal phosphate. After 1 mo of abstinence from alcohol, with intake of an adequate diet and pyridoxine supplementation, plasma pyridoxal phosphate increased in all patients with initially low values (p less than 0.02). Serum aspartate aminotransferase decreased, whereas serum alanine aminotransferase increased, resulting in a decrease in their ratio in serum (p less than 0.001). Liver alanine aminotransferase increased (p less than 0.005), whereas liver aspartate aminotransferase remained unchanged. These data suggest that pyridoxal 5'-phosphate depletion is partially responsible for the low serum alanine to aspartate aminotransferase ratio that is typical of patients with alcoholic hepatitis.

Acute Disease↗
PubMed1983

Dealing with suicide on a psychiatric inpatient unit.

Suicide on an inpatient unit can cause severe trauma among patients and staff. Consequently both groups may revert to less adaptive coping styles. In general, staff's recovery is gradual and natural and may yield an opportunity for emotional growth; however, prolonged disability may also occur. The authors interviewed 23 staff members who had worked on an inpatient unit during a 16-month period when four patients committed suicide. On the basis of these interviews, the authors have developed a framework for understanding the three phases of staff reaction to suicide and guidelines for helping staff through the recovery process. They recommend that ward administrators monitor and facilitate the group process by providing protection and support during the initial phase of shock, appropriate channels and limits for the intense feelings that occur during the second phase, and constructive forums for more mature coping activities during the third phase, as staff regain their equilibrium.

Adaptation, Psychological↗
PubMed1982

Insulin-induced hypoglycaemia in an accident and emergency department: the tip of an iceberg?

In one year a prospective survey in a large accident and emergency department identified 204 admissions of adults with severe hypoglycaemia, 200 in insulin-treated patients. Ninety-six had one admission while 34 others were admitted on 104 occasions. Of the 130 patients, 111 attended diabetic clinics in Nottingham, forming 9% of a known clinic population of 1229 on insulin treatment. Since many other episodes of hypoglycaemia were presumably treated outside hospital, 9% a year is a minimum estimate of the incidence of severe hypoglycaemia in our area. The mean insulin dose was 1.2 units/kilogram/day for those admitted twice or more and 0.9 U/kg/day for those admitted once; these doses were significantly higher than those of an age-matched clinic population. A year after the latest admission with hypoglycaemia, the mean insulin dose in the group with two or more admissions had fallen to 0.8 U/kg/day, suggesting that over-treatment had been an important causal factor. A similarly high incidence has been reported in other studies, and we believe that it is due mainly to the inadequacy of conventional subcutaneous insulin treatment.

Adolescent↗