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Biomedical subjects

M A Morris

Publications and source records attributed to M A Morris.

At least 109 records · Page 6Linked to original sources
PubMed1987

Gestational diabetes: maternal response to diet and insulin therapy as reflected by glycosylated hemoglobin concentration.

To assess the effects of diet and insulin therapy on pregnancy complicated by gestational diabetes, glycosylated hemoglobin concentration was determined longitudinally in 32 women. Diet was instituted when a diagnosis of gestational diabetes was made and was supplemented with insulin for fasting hyperglycemia. At initial presentation, glycosylated hemoglobin concentration was increased in the 18 women who required insulin compared with the 14 women managed by diet alone (7.1% +/- 0.2% versus 6.2% +/- 0.2%, mean +/- SEM, p less than 0.01). Diet had no effect on glycosylated hemoglobin concentration that remained elevated to 6.1% +/- 0.3% compared with the glycosylated hemoglobin concentration of 5.6% +/- 0.2% for pregnant nondiabetic women (p less than 0.01). Insulin resulted in a decrease in glycosylated hemoglobin concentration within 3 to 5 weeks (p less than 0.05). After 7 to 9 weeks of insulin and diet, the glycosylated hemoglobin concentration in women with fasting hyperglycemia was the same as the glycosylated hemoglobin concentration in women who were managed by diet alone.

Adult↗
PubMed1987

Potential retinal hazards of visible-light photopolymerization units.

We evaluated the potential for retinal damage, both thermal and photochemical, from commercially available visible-light photopolymerization units. The spectral radiance profiles of 11 visible-light photopolymerization units were measured by means of a spectroradiometer and the results weighted according to the American Conference of Governmental Industrial Hygienists (ACGIH) Blue Light Hazard Function and Thermal Hazard Function. The values were then integrated by means of the proposed ACGIH hazard formulae, so that we could determine the maximum permissible exposure (tMAX) duration for each light. This calculation assumed a worst-case condition of direct vision of the light source from a distance of 25 cm. The results indicate that there is no thermal hazard to the retina. The tMAX duration values for the photochemical (blue light) hazard to the retina ranged from 2.4 minutes per day (for the most hazardous unit) to 16.0 minutes per day (for the least hazardous). None of these hazard times is short enough to be of concern unless the individual operator elects to focus on the light source or the reflected output from these visible-light photopolymerization units for an extended period of time.

Dental Restoration, Permanent↗
PubMed1986

Background size and saturation of the rod system.

To determine the effect of background size on saturation of the human rod system, we measured threshold-vs-intensity (tvi) functions for a 24'-diameter, middle-wavelength test stimulus against long-wavelength background fields that were either 2 degrees or 8 degrees in diameter. When thresholds were measured against a series of background intensities presented during a single experimental session (a standard tvi procedure), rod increment thresholds were higher against the smaller background and eventually disappeared above cone increment thresholds at moderate background intensities. This result suggests that background diameter does influence rod system saturation. However, when adaptation to the smaller background was limited to a 5 min exposure to a single background intensity per experimental session, then thresholds against that background were rod- rather than cone-mediated and were comparable to rod thresholds against an 8 degrees background. Therefore, under these stimulus conditions, background size apparently does not influence rod system saturation unless adaptation to the smaller background is prolonged. Based on previous studies, we suggest that the rod-desensitizing effect of small backgrounds under conditions of prolonged adaptation is due to a post-retinal mechanism.

Adaptation, Ocular↗
PubMed1986

Glycosylation accelerates albumin degradation in normal and diabetic dogs.

Nonenzymatic glycosylation of albumin was associated with an increased catabolic rate and decreased protein half-life in both normal and diabetic animals. The fractional catabolic rate of glycosylated albumin was increased significantly over albumin, from 0.100 +/- 0.004/day to 0.131 +/- 0.007/day in normal animals and from 0.104 +/- 0.004/day to 0.138 +/- 0.007/day when these animals were made diabetic with alloxan. The half-lives of Alb and GlyAlb in normal dogs were 6.81 +/- 0.12 days and 4.97 +/- 0.21 days, respectively. In diabetic animals, the half-lives of Alb and GlyAlb were 7.48 +/- 0.21 and 5.21 +/- 0.24 days, respectively. The increased catabolism of GlyAlb may reflect chronic increased extravasation of glycosylated plasma proteins, which are known to be increased in diabetes, into the microvascular wall.

Animals↗
PubMed1986

Glycosylated hemoglobin: a sensitive indicator of gestational diabetes.

Previous studies suggested that the assessment of hemoglobin A1 (HbA1) concentration was a poor indicator of diabetes in pregnancy. However, HbA1 was measured by ion exchange chromatography, which is subject to spurious alterations. To reevaluate the use of glycosylated hemoglobin concentration (GlyHb) as an indicator of gestational diabetes, 64 women at 10 to 15 weeks' gestation were studied by measuring GlyHb by a specific affinity chromatography assay, and blood glucose concentration was determined one hour post a 50-g oral glucose load. Gestational diabetes developed in 15 women in whom GlyHb (7.4 +/- 0.2%) was greater than in normal pregnant women (5.7 +/- 0.1%, P less than .001). If a GlyHb of 6.3% were chosen as the threshold for diagnostic evaluation for diabetes, only 6.7% of the gestational diabetics would have missed diagnosis. Of normal women, 14.2% would have been subjected to glucose tolerance test. GlyHb elevation was associated with the birth of infants large for gestational age. The assessment of GlyHb by affinity chromatography between 10 and 15 weeks' gestation may be a sensitive predictor of patients who will develop gestational diabetes.

Adolescent↗
PubMed1986

The intravenous insulin tolerance test in type I diabetes.

The intravenous insulin tolerance test (ITT) allows general assessment of insulin sensitivity by determining the fall in plasma glucose after injection of 0.1 unit/kg regular insulin. To evaluate the usefulness of this test diagnostically in distinguishing Type I from Type II diabetes, 24 patients with Type I diabetes (defined as early age of onset, ideal body weight or less at onset, and insulin dependence) underwent ITTs. Seven patients had normal glucose disposal rates (Ki greater than or equal to 2.5. Nine patients had Ki less than 2.5 but greater than 1.0. Eight patients had Ki less than 1.0. The slopes did not correlate with the control of the diabetes (as assessed by measurement of glycosylated hemoglobin), the presence or titer of anti-insulin antibodies, the duration of the diabetes, the age of onset, the presence of complications, or the current insulin dose. These results indicate that varying amounts of insulin resistance may be present in Type I diabetes and cannot necessarily be explained by poor control or the presence of insulin antibodies.

Adolescent↗
PubMed1985

Glycosylated hemoglobin concentration in early gestation associated with neonatal outcome.

Previous studies have indicated an association of fetal macrosomia with mild degrees of glucose intolerance in late pregnancy. To determine whether glycosylated hemoglobin concentration in early gestation was related to fetal outcome, 48 pregnant women with normal glucose tolerance and 21 women with gestational diabetes were studied. Glycosylated hemoglobin concentration was determined by a specific aminophenylboronic acid assay, and mean glycosylated hemoglobin concentration was calculated from two or three determinations before 17 weeks' gestation. The incidence of infants large for gestational age was 10% in nondiabetic women with glycosylated hemoglobin concentration of less than 6.0%. With glycosylated hemoglobin concentration of 6.0% to 6.9%, the incidence of infants who were large for gestational age was increased in both nondiabetic women (75%, p less than 0.01) and diabetic women (40%, p less than 0.01). With glycosylated hemoglobin concentration of greater than 7.0%, 36% of infants of diabetic women were large for gestational age. The incidence of hyperbilirubinemia was 2.5% in the infants of nondiabetic women with glycosylated hemoglobin concentration of 6.0%. With glycosylated hemoglobin concentration of 6.0% to 6.9%, hyperbilirubinemia was increased in both the infants of nondiabetic women (38%, p less than 0.01) and diabetic women (30%, p less than 0.01). With glycosylated hemoglobin concentration of greater than 7.0%, hyperbilirubinemia was present in 27% of infants of diabetic mothers. The current study suggests that glycosylated hemoglobin concentration elevation in early gestation is associated with perinatal morbidity.

Apgar Score↗
PubMed1985

The correlations of glycosylated serum protein and glycosylated hemoglobin concentrations with blood glucose in diabetic pregnancy.

The usefulness of concentrations of glycosylated serum protein and glycosylated hemoglobin in monitoring glycemic control during pregnancy complicated by diabetes was evaluated by correlation of these parameters with fasting and 2-hour postprandial glucose concentrations of the previous 7 days. Glycosylated serum protein correlated with both fasting (r = 0.798, p less than 0.01, n = 71) and postprandial (r = 0.846, p less than 0.01, n = 69) blood glucose concentrations. Glycosylated hemoglobin also correlated with fasting (r = 0.571, p less than 0.01, n = 71) and postprandial (r = 0.510, p less than 0.01, n = 74) blood glucose concentrations. Monitoring glycosylated serum protein during pregnancy complicated by diabetes is clinically feasible and allows frequent reappraisal of diabetic control.

Adult↗
PubMed1985

Anti-thymocyte globulin and prednisone immunotherapy of recent onset type 1 diabetes mellitus.

Increasing evidence that Type 1 (insulin dependent) diabetes mellitus is an autoimmune disease, together with successful cure/prevention in animal models of this disease (e.g. BB/W rat) has led to several trials of immunotherapy in recent onset Type 1 diabetes of man. In this communication we report our experience with short courses of prednisone and antithymocyte globulin (ATGAM) plus prednisone. Prednisone characteristically suppressed Ia positive T lymphocytes into the normal range, but had no long-lasting effect on T-cell phenotype. ATGAM plus prednisone markedly decreased the ratio of T4/T8 ("helper"/"suppressor-cytotoxic") positive T lymphocytes, and this remained suppressed for months. ATGAM treated patients had lower HbA1c on a lower dose of insulin 100 or more days following immune therapy (with 4 out of 5 patients requiring less than 0.2 U/Kg insulin/day). Two patients in the ATGAM treated group did not require insulin for more than 8 months; during remission they had normal fasting blood glucose values, but with abnormal glucose tolerance on oral glucose tolerance testing. Severe, though transient, thrombocytopenia was observed in 2 patients on ATGAM therapy which outweighed its clinical effects.

Adolescent↗
PubMed1984

Differential sensitivity to beta-cell secretagogues in "early," type I diabetes mellitus.

The insulin secretory response to various beta-cell secretagogues was studied in four children (ages 11, 11, 12, and 10 yr) in "early" stages or remission of type I diabetes mellitus. One child was an anti-islet antibody positive monozygotic twin of a type I diabetic subject, two children had impaired glucose tolerance and elevated levels of Ia-positive T-cells, and the fourth was in remission (off insulin) of type I diabetes 6 mo after immunotherapy. The peak first-phase (0-10 min) insulin increment after intravenous (i.v.) glucose was negligible in each patient, whereas the peak responses to i.v. glucagon, tolbutamide, arginine, and oral glucose ranged between 10% and 43% of median responses in normal control subjects. The rank order of response to a variety of secretagogues was remarkably similar in all four subjects: i.v. arginine greater than i.v. glucagon greater than oral glucose greater than i.v. tolbutamide greater than i.v. glucose. These studies indicate that a "functional" beta-cell defect, namely a complete loss of response to i.v. glucose and a partial loss to other secretagogues, exists in type I diabetic patients before complete beta-cell destruction. This alteration in beta-cell responsiveness probably underlies our prior observation of slowly progressive loss of i.v.-glucose-induced insulin release in islet cell antibody-positive siblings to type I diabetic subjects.

Arginine↗
PubMed1982

University of Manchester sports injury clinic.

This paper reviews the work of the sports injury clinic based at the Student Health Centre, University of Manchester during its first eighteen months. A total of 852 patients including 46 Centre of Excellence athletes were treated. The results indicate that the establishment of such a specialised clinic is worthwhile, that the injured sportsmen should be treated by individuals trained and interested in the treatment of injured patients in general and that the commonest injuries are soft tissue injuries to the knee of ankle joint. A record card, designed for future computer analysis, is illustrated. It includes details of the sport, training, mechanism of injury, pathology and treatment.

Athletic Injuries↗
PubMed1981

Cytotoxic antibodies to cloned rat islet cells in serum of patients with diabetes mellitus.

We have found complement-dependent cytotoxic antibodies in the serum of 8 of 24 patients with insulin-dependent diabetes mellitus using a 51Cr cytotoxicity assay with monolayers of cloned rat islet cells (clones RINm 5F and RINm 14B). In contrast, complement-dependent cytotoxicity with 51Cr release greater than 24% was found with sera from 34 controls or from 5 patients with polyglandular failure without diabetes, and was present in only 1 serum our of 12 from patients with insulin-independent diabetes mellitus. The prevalence of antibodies appears to decrease with duration of insulin-dependent diabetes, and in one patient studied, cytotoxic antibodies were present at the time of diagnosis of diabetes. Cytotoxicity is independent of insulin synthesis, as evidenced by the linear correlation of cytotoxicity of sera for the insulin-producing clone RINm 5F and the somatostatin-producing clone RINm 14B. The present study identifies nonspecies-specific cytotoxic antibodies in the serum of patients with diabetes mellitus, and the assay used should facilitate studies of humoral immunity in the pathogenesis of diabetes mellitus.

Adult↗
PubMed1980

Use of tracer microspheres to measure bone blood flow in conscious dogs.

Blood flow was measured in mature and immature dogs by means of tracer microspheres. Microspheres of 15 micron were found to be the most suitable size in the dog. Total body nonentrapment in the awake, standing dog is likely to be less than 10%. Cortical bone flood flow, devoid of periosteum and marrow, is 2.5 ml/100 g/min in mature dogs and 7.0 ml/100 g/min in immature dogs, P < 0.005. Blood flow in cancellous bone is greater than that in cortical bone in mature (P < 0.001) and immature (P < 0.02) dogs. Flow is different in different regions of a long bone because of different proportions of cortical and cancellous bone, probably because of interrelationships of function (surfaces undergoing remodeling) and, therefore, of energy metabolism and blood flow.

Animals↗
PubMed1979

Enhanced nonenzymatic glucosylation of human serum albumin in diabetes mellitus.

Use of an ion exchange chromatographic method and a colorimetric method with thiobarbituric acid showed that levels of nonenzymatically glucosylated serum albumin were increased in patients with poorly controlled diabetes mellitus compared to controls. The two methods correlated well (r = 0.99) and clearly discriminated between normal and poorly controlled diabetic populations. The levels of glycosylated hemoglobin were also measured in both populations. Several patients apparently in good control based on glycosylated hemoglobin measurements were found to have increased levels of glycosylated albumin. Because albumin has a shorter circulating half-life than does the human erythrocyte, the plasma concentration of glucosylated albumin should be expected to reflect short-term control of hyperglycemia in diabetes. The studies reported here suggest that the level of glucosylated albumin may indeed be a sensitive indicator of moderate hyperglycemia and of early glucose intolerance.

Blood Glucose↗