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Biomedical subjects

M S Rendell

Publications and source records attributed to M S Rendell.

29 records · Page 2Linked to original sources
PubMed1990

Aldose reductase inhibitors.

The present management of diabetes consists of attempting to control blood sugar tightly in the normal range and to treat individual complications such as neuropathy and retinopathy as they appear. Whereas these measures are perhaps effective in slowing the progress of diabetic complications, they do not cure the underlying process. The aldose reductase inhibitors have been investigated as possible remedies for various diabetic complications. Aldose reductase is an enzyme present in several human tissues that reduces glucose to sorbitol. In animal models there is evidence that the production of sorbitol is associated with the development of diabetic complications. Animal and human studies have tested the ability of aldose reductase inhibitors to halt or reverse diabetic complications. The weight of evidence leads to two conclusions: first, that aldose reductase inhibitors may bring significant relief to patients with certain diabetic complications; and second, that the current approach to proving clinical efficacy may not be adequate for these drugs.

Aldehyde Reductase↗
PubMed1989

A comparison of nerve conduction velocities and current perception thresholds as correlates of clinical severity of diabetic sensory neuropathy.

Nerve conduction velocities (NCVs) are the standard measurements used to confirm the presence or absence of diabetic neuropathy. NCVs were contrasted with the newer technique of measurement of alternating current perception thresholds (CPTs) in assessing the quantitative level of correlation with severity of diabetic sensory neuropathy. A very detailed, scored neurological history (symptoms) and physical examination, emphasising sensory assessment, was conducted on 71 individuals with diabetic neuropathy of varying degrees of severity. Sensory and motor NCVs and CPTs at 5, 250, and 2000 Hz of the upper and lower extremities were determined for these individuals. In addition, vibration thresholds (VTs) were measured as a third modality. Twenty eight individuals underwent repeated evaluations at 2, 6, 10 and 12 months after the initial procedures. Using the results of 169 complete evaluations, correlations were determined between physical scores (PS) and symptoms scores (SS) and NCVs. NCV correlations with the SS were weaker than with the PS. The strongest of the correlations were found between the PS and motor NCVs of the median nerve (rho = 0.29) and the tibial nerve (rho = 0.38). Normal NCVs were present in the face of very significant historical and physical abnormality. Correlations of the SS and PS with both VTs and CPTs were higher than with the NCVs. CPTs proved the more effective as predictors of both symptomatic and physical impairment. NCVs appear to lack the resolving power necessary to evaluate subtle differences in clinical state of diabetic sensory neuropathy. The supplementary use of current perception testing may improve the quantitative assessment of this condition.

Arm↗
PubMed1989

Mapping diabetic sensory neuropathy by current perception threshold testing.

Detailed clinical neurological examinations were conducted on 44 nondiabetic volunteers and 59 diabetic subjects. The examinations focused particularly on sensory symptomatic and physical evaluation. Standardized assessment of symptoms and physical testing of light touch, pain, vibratory, and thermal sensation was performed at the hand, wrist, elbow, foot, ankle, and knee. A total symptom score and physical score were defined by summing test scores at each site. Current perception threshold (CPT) testing that used constant sine-wave-alternating current was conducted at the same anatomic sites. CPT correlations with the physical score gave r values of .55 for 5 Hz, .60 for 250 Hz, and .62 for 2000 Hz (n = 618). Correlations with the symptom score were not as strong: r = .45 for 5 Hz, .46 for 250 Hz, and .51 for 2000 Hz. The correlation with symptom score was due primarily to a strong relationship for the symptom of numbness (r = .53 for all 3 frequencies). Correlations with pain and paresthesia were much lower. CPTs for diabetic subjects at the three frequencies were higher at most locations than for the nondiabetic volunteers. However, CPTs were no different from normal values in diabetic subjects without evidence of neuropathy. CPT testing appears to be a useful technique for assessment of diabetic sensory neuropathy.

Adult↗
PubMed1987

Constant current sine wave transcutaneous nerve stimulation for the evaluation of peripheral neuropathy.

We have evaluated various forms of peripheral neuropathy with a new device which emits a constant sinusoid stimulus at varying frequencies to quantitate current perception thresholds (CPTs). In normal individuals, CPT measures increase with increasing stimulation frequency, are highest on the toe and lowest on the face. There is a significant effect of age and sex on threshold perception. In patients with neuropathy, there is a marked increase in thresholds on hands and feet, as well as a lesser but still significant increase of facial CPTs. Thresholds furthermore correlated with clinical severity in a group of patients with diabetic neuropathy. Facial thresholds were markedly elevated in the patients with moderate to severe neuropathy, suggesting that the device is sensitive to the systemic nature of peripheral neuropathy. The authors believe the device will be a useful tool in screening for sensory neurologic abnormalities.

Adult↗
PubMed1987

Gestational diabetes.

The perinatal morbidity and mortality associated with gestational diabetes can be significantly reduced when cases are recognized and closely monitored. There is much controversy about the diagnosis of gestational diabetes and the practicality of universal screening.

Blood Glucose↗
PubMed1981

Hyperlabile diabetes accompanied by insulin resistance.

It is generally held that high insulin antibody concentrations, by "buffering" abrupt swings in free insulin concentrations after injections of exogenous insulin, tend to stabilize blood glucose variations in diabetic patients. However, we encountered a patient with extremely labile diabetes coexisting with insulin resistance. This patient's injections were switched to pure porcine insulin from his usual mixed bovine/porcine insulin, in an effort to decrease his insulin requirement. This treatment was successful, and, as his insulin dosage decreased, his diabetic lability diminished substantially. His diabetes was eventually considered stabilized on about 22 units of porcine insulin daily. The serial decrease in his insulin antibody concentrations, monitored by use of solid-phase radioimmunoassay, paralleled the disappearance of his diabetic lability as well as the decrease in his insulin requirement.

Adult↗
PubMed1977

Activation of hepatic adenylate cyclase by guanyl nucleotides. Modeling of the transient kinetics suggests an "excited" state of GTPase is a control component of the system.

A three-state model developed originally from analysis of the steady state kinetics of hepatic adenylate cyclase has been extended to account for the transient kinetics of activation by guanyl-5'-yl imidodiphosphate (Gpp(NH)p). In contrast to activation by Gpp(NH)p, activation of the enzyme by GTP proceeds not only without a lag phase but is of considerably lower magnitude. These differences between Gpp(NH)p and GTP can be explained by the hypothesis that GTP is hydrolyzed at the nucleotide regulatory site(s) associated with adenylate cyclase and that GTPase activity is revealed uniquely when the enzyme system is in its state of highest adenylate cyclase activity. With this hypothesis, the characteristics of activation by GTP could be simulated. The implications of this model are discussed with respect to the actions of hormones and cholera toxin on adenylate cyclase activity.

Adenylyl Cyclases↗
PubMedDate not supplied

Pharmacotherapy of type 2 diabetes mellitus.

OBJECTIVE: To review the drug treatments and some of the popular, nontraditional remedies now available for type 2 diabetes mellitus, as well as selected investigational agents; to describe each medication's place in the overall approach to treatment. DATA SOURCES: English-language journals, abstracts, review articles, and newspaper accounts. DATA SYNTHESIS: In the past five years, there has been tremendous progress in the pharmacotherapy of diabetes, particularly type 2 diabetes. Several new agents have entered the clinical arena, and many more are in the late stages of investigation leading to approval. Sulfonylureas stimulate the production and release of insulin; these drugs must be used in patients with an intact pancreas. The meglitinides are nonsulfonylurea agents that are also insulin secretagogues. Unlike the sulfonylureas, repaglinide appears to require the presence of glucose to close the adenosine triphosphate-sensitive potassium channels and induce calcium influx. Metformin reduces hepatic glucose production in some patients and increases peripheral glucose utilization, but its use is hampered by a high percentage of adverse reactions. Disaccharidase inhibitors effectively compensate for the defective early-phase insulin release by slowing the production of sugars from carbohydrates. Thiazolidinediones appear to activate peroxisome proliferator-activated receptor gamma, which is involved in the metabolism of lipids. Short-acting insulin and the role of weight-loss agents are also discussed. CONCLUSIONS: The availability of new options for diabetes therapy provides a chance for successful therapy in a larger number of patients. However, it is important to consider how much true benefit these new forms of treatment will have on the diabetic community. The best choice for a patient remains controversial.

Anti-Obesity Agents↗