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Biomedical subjects

M Lemon

Publications and source records attributed to M Lemon.

At least 37 records · Page 2Linked to original sources
PubMed1989

Kinetics of digoxin and anti-digoxin antibody fragments during treatment of digoxin toxicity.

Anti-digoxin antibody fragments (ADAF, 80 mg) were infused intravenously to successfully treat severe digoxin toxicity in an 82 year old woman. During treatment, total and free digoxin were determined using an Abbot TDX analyser and an ultrafiltration technique. ADAF were measured by an enzyme-linked immunosorbent assay. By 1 h after ADAF, total serum digoxin concentrations had risen 12-fold from a pretreatment level of 15.4 nmol l-1 but free digoxin fell from 10 to 0.1 nmol l-1, indicating greater than 99.9% digoxin binding to ADAF. However, the low free levels had rebounded to 7.7 nmol l-1 by 12 h, but despite this rise the patient's condition had improved. A serum ADAF/digoxin molar ratio of around five was associated with the low concentration of free digoxin at 1 h, while at later times with ratios roughly between 3 and 4, the free digoxin concentrations ranged between 2.0 and 7.7 nmol l-1. ADAF were mainly confined to the plasma during the first hour, but subsequently distributed into an apparent volume of 193 ml kg-1. The elimination half-lives of ADAF and total digoxin were 96 and 55 h, respectively. More than 50% of the estimated digoxin load had been excreted in the urine by 5 days; for ADAF the equivalent figure was only about 3%. Renal and/or bacterial degradation may have contributed to the low detection of urinary ADAF.

Aged↗
PubMed1989

Distractibility in schizophrenia: state and trait aspects.

This report compared the selective attention of 19 schizophrenic in-patients, 10 recently discharged schizophrenic out-patients, 21 schizophrenic out-patients in stable clinical remission, 33 first-degree relatives of schizophrenics from 15 families, 25 students who scored deviantly on questionnaire measures of magical ideation, perceptual aberrations, and physical anhedonia, and 20 normal controls. Results indicated that distractors only disrupted the performance of schizophrenic in-patients, suggesting that differential deficits in selective attention are a marker of episodes of schizophrenia. A propensity to interject phonemes from the distracting message was found not only in patients in or just emerging from a psychotic episode, but also in the remaining vulnerable but non-psychotic groups, suggesting that intrusion errors might be a mediating vulnerability marker. The findings suggest both state and possibly trait aspects to distractibility in schizophrenia.

Adult↗
PubMed1987

Thyroid function in trophoblastic disease.

Human chorionic gonadotrophin (hCG) levels and thyroid function were monitored in 44 patients receiving chemotherapy for treatment of trophoblastic disease. We observed a strong correlation between hCG and thyroid stimulating hormone (TSH) concentrations measured by radioimmunoassay, and this appears to be due to cross-reactivity between hCG and the anti-TSH antibody used. The concentration of thyroid hormones was little affected by the raised levels of TSH or hCG, except when the concentration of the latter rose to high levels, usually above 100,000 i.u./l. The possible mechanisms of thyroid homeostasis in trophoblastic disease are considered.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1986

Thermal biofeedback and periodic movements in sleep: patients' subjective reports and a case study.

Periodic movements in sleep (PMS) is a sleep disorder characterized by repetitive leg kicks accompanied by arousals. In our clinical experience, many patients with PMS anecdotally report that they suffer from cold feet. This study explored whether there is an increased incidence of cold feet complaints in patients with periodic movements in sleep. Results indicated that, indeed, significantly more patients with leg kicks complain of cold feet as compared to patients without leg kicks. A case study was then conducted to determine whether foot thermal biofeedback training would alleviate symptoms of periodic movements in sleep. The number of leg kicks decreased from a mean of 536 per night before biofeedback training to a mean of 19.5 after training. These data lend support to our hypothesis that poor circulation may be contributing to the severity of periodic movements in sleep and that thermal biofeedback may afford an alternative treatment strategy.

Aged↗
PubMed1982

Interaction between two luteal cell types from the corpus luteum of the sow in progesterone synthesis in vitro.

Populations of two types of luteal cell (large and small) were prepared from CL of sows at 60 days of gestation. When the two types were recombined and incubated for 2 h, the amount of progesterone released into the medium was almost twice the sum of that released by each cell type alone. When the cells were superfused in vitro, in an "in series" arrangement such that the superfusate from one cell type then passed through the chamber containing the second cell type, the small cells were responsible for increasing the production of progesterone by the large cells. When cell population were superfused with media containing inhibitors of progesterone synthesis, trilostane completely blocked progesterone release but aminoglutethimide only reduced progesterone output by half, even when the concentration of inhibitor was increased. Addition of pregnenolone to the superfusion medium increased progesterone production by both cell types approximately 3-fold, whereas addition of cholesterol only increased progesterone production by the large cells.

Abortifacient Agents, Steroidal↗
PubMed1980

The metabolism of cyclic nucleotides in the guinea-pig pancreas. Cyclic AMP phosphodiesterase and cyclic GMP phosphodiesterase.

Both cyclic AMP phosphodiesterase and cyclic GMP phosphodiesterase were recovered mainly from the supernatant fractions of guinea-pig pancreas, but a higher proportion of the activity of the former was associated with the pellet fractions. The activities in the supernatant were not separated by gel filtration, but were clearly separated by subsequent chromatography on an anion-exchange resin. The activities of cyclic AMP phosphodiesterase and cyclic GMP phosphodiesterase had high-affinity (K(m) 6.5+/-1.1mum and 31.9+/-3.9mum respectively) and low-affinity (K(m) 0.56+/-0.05mm and 0.32+/-0.03mm respectively) components. The activity of neither enzyme was affected by the pancreatic secretogens, cholecystokinin-pancreozymin, secretin and carbachol. Removal of ions by gel filtration resulted in a marked reduction in cyclic nucleotide phosphodiesterase activity, which could be restored by addition of Mg(2+). Mn(2+) (3mm) was as effective as Mg(2+) (3mm) in the case of cyclic AMP phosphodiesterase, but was less than half as effective in the case of cyclic GMP phosphodiesterase. The metal-ion chelators, EDTA and EGTA, also decreased activity. Ca(2+) (1mm) did not affect the activity of cyclic nucleotide phosphodiesterase when the concentration of Mg(2+) was 3mm. At concentrations of Mg(2+) between 0.1 and 1mm, 1mm-Ca(2+) was activatory, and at concentrations of Mg(2+) below 0.1mm, 1mm-Ca(2+) was inhibitory. These results are discussed in terms of the possible significance of cyclic nucleotide phosphodiesterase in the physiological control of cyclic nucleotide concentrations during stimulus-secretion coupling.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1980

The metabolism of cyclic nucleotides in the guinea-pig pancreas. Adenylate cyclase and guanylate cyclase.

Adenylate cyclase from the guinea-pig pancreas was activated in a dose-dependent manner by both secretin and cholecystokinin-pancreozymin, but in contrast with results in other species the hormones were approximately equipotent. All other hormones and transmitter substances tested were without any effect on adenylate cyclase activity. Guanylate cyclase activity was shown to have both particulate and supernatant components in the guinea-pig pancreas. The particulate enzyme, but not the supernatant enzyme, was markedly activated by Triton X-100, and most of the induced activity was released into the supernatant. The supernatant enzyme was specifically Mn2+-dependent, but, even though Mn2+ was maximally effective at a concentration of 3 mM, activity could be raised further by increasing Ca2+ concentration. The particulate enzyme, by contrast, was relatively Mn2+-independent. Activity of the particulate guanylate cyclase was enhanced by phosphatidylserine. The supernatant enzyme displayed classical Michaelis-Menten kinetics, but the particulate enzyme deviated markedly from such kinetics. Under none of the conditions used was any significant activation of guanylate cyclase observed with any of the secretogen hormones or transmitter substances.

Adenosine Triphosphate↗
PubMed1979

The isolation and properties of pig submandibular kallikrein.

The kallikrein from pig submandibular glands was highly purified, with an overall yield of 31%. Affinity chromatography on bovine basic pancreatic trypsin inhibitor linked to Sepharose 4B was an especially effective step in the purification procedure, giving a purification factor of 80. The enzyme is a single-chain molecule, occurring, as does pig urinary kallikrein, as a major B-form of apparent mol.wt. 39600 and minor amounts of an A-form of apparent mol.wt. 35900; the two forms can be separated by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. The amino acid composition of pig submandibular kallikrein is very similar to, but not quite identical with, that of the two-chain beta-kallikrein isolated from pig pancreatic autolysates. Submandibular kallikrein contains notably more glucosamine and hexoses than does pancreatic beta-kallikrein. Submandibular kallikrein, and also urinary kallikrein, exhibit an unusual biphasic hydrolysis of substrate esters that is not shared by pancreatic beta-kallikrein. For the submandibular enzyme, the K(m) for the initial reaction phase of the hydrolysis of alpha-N-benzoyl-l-arginine ethyl ester is 0.15+/-0.01mm (mean+/-s.e.m.), but rises to 0.69+/-0.04mm (mean+/-s.e.m.) in the stationary reaction phase; the V(max.) does not differ significantly between the two phases. The esterolytic activities of submandibular and urinary kallikreins on a number of esters of different amino acids resemble each other much more closely than those of pancreatic beta-kallikrein.

Amino Acids↗
PubMed1977

Steroid release in vitro by two luteal cell types in the corpus luteum of the pregnant sow.

Corpora lutea from sows at 30, 60 and 90 days of gestation were dissociated enzymically, and the components of the resulting cell suspension were separated by sedimentation at unit gravity. Two luteal cell populations of 30-50 micronm diameter and 15-20 micronm diameter were obtained and superfused for up to 18 h with Dulbecco's modified Eagle medium, the cells being supported in a column in a matrix of Biogel. Fractions were collected every 30 min and assayed for progesterone and oestradiol-17beta. At 30 and 60 days of gestation the large luteal cells produced progesterone at an initial rate of approximately 100 ng/h/10(5) cells, which decreased to half this rate at 90 days. The smaller cells also released progesterone into the medium at approximately 15-20 ng/h/10(5) cells at all stages of gestation. At 30 days of gestation, neither cell type released significant amounts of oestradiol-17beta, but from 60 days onwards ,significant and increasing quantities were measured in the superfusates from the larger cells. Both cell types were perfused with porcine LH at the three stages of gestation, and both showed an immediate response in terms of progesterone release which decreased in magnitude with increasing age of gestation. The response of the smaller cells was greater than that of the larger cells.

Animals↗