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Biomedical subjects

R D Welch

Publications and source records attributed to R D Welch.

53 records · Page 3Linked to original sources
PubMed1989

Evaluation of the effects of intra-articular injection of dimethylsulfoxide on normal equine articular tissues.

To evaluate the effects of intra-articular injection of dimethylsulfoxide (DMSO) on normal equine articular structures, 7 adult horses with clinically normal carpi were allotted to 2 treatment groups (group A, n = 4; group B, n = 3). In each horse after collection of synovial fluid samples, the right antebrachial carpal and middle carpal joints were aseptically injected with 2 ml of a 40% solution of 90% medical grade DMSO in lactated Ringer solution, and the corresponding joints of the left forelimb (controls) were injected with 2 ml of lactated Ringer solution. In group-A horses, 2 ml of synovial fluid was obtained prior to injections of 40% DMSO at 24 hours and 72 hours, for a total of 3 injections. At necropsy, synovial fluid, synovial membrane, and articular cartilage specimens were obtained. Group-B horses were injected with 40% DMSO in the same sequence; however, the series was repeated following a 1-week interval. Clinical evaluation of these horses revealed no evidence of carpal inflammation associated with any injection in any group. Synovial fluid analysis of DMSO-injected and control joints revealed insignificant differences in leukocyte counts and total protein content. There was no evidence of cartilage degradation on gross, histologic, or histochemical evaluation of any of the joints. Intercellular matrix staining of the articular cartilage failed to reveal any observable difference in glycosaminoglycan content between injection with DMSO or lactated Ringer solution.

Animals↗
PubMed1988

Phenytoin loading in chronic alcoholic patients.

Controversy exists concerning the appropriate loading dose of phenytoin in chronic alcoholic patients. Chronic alcoholics are frequently assumed to have low albumin levels secondary to malnutrition and liver disease. Phenytoin is bound to albumin, and therefore the usual loading dose of phenytoin might result in a higher percentage of unbound drug and increased toxicity in these patients. Thirty-six chronic alcoholic patients were given a 15-mg/kg loading dose of phenytoin by constant intravenous infusion. After the infusion, patients were evaluated for clinical signs of phenytoin toxicity. At 1 hour after infusion, blood was sent for determination of total phenytoin, free phenytoin, and albumin levels. Fifteen patients were hypoalbuminemic (mean, 3.4 g/dL); 21 patients had albumin levels within the normal range (mean, 4.3 g/dL). In the hypoalbuminemic group, the mean free phenytoin level was 1.1 micrograms/mL, and the mean total phenytoin level was 13.6 micrograms/mL. In patients with normal albumin levels, the mean free phenytoin level was 1.3 micrograms/mL, and the mean total phenytoin level was 15.7 micrograms/mL. There were no statistically significant differences in total phenytoin or free phenytoin levels between either groups. No patient had a postinfusion phenytoin level (either free or total) within the toxic range. Although our sample size was small, our results suggest that a 15-mg/kg loading dose of phenytoin does not produce toxic levels in chronic alcoholics.

Adult↗
PubMed1987

Herd evaluation of Fasciola hepatica infection levels in Louisiana cattle by an enzyme-linked immunosorbent assay.

An enzyme-linked immunosorbent assay (ELISA) was evaluated as a method of determining relative immunoconversion rates in calves and how immunoconversion rates and strength of optical density values correlate with prevalence of Fasciola hepatica fecal egg shedding. Ten to 55 calves and cows were examined from each of 10 separate beef cattle herds in central and southern Louisiana. Infection prevalence rates for calves averaged 8% higher when ELISA optical density values were used than those when fecal egg count data were used. Of 55 calves in 8 herds that were ELISA positive, 39 were shedding F hepatica eggs; of 53 calves that were shedding eggs, 14 were ELISA negative. Significant correlation of calf fecal and ELISA prevalence was observed for 8 herds by linear regression analysis. A chi 2 analysis showed that calf ELISA and fecal egg shedding data were not independent. Results indicate that positive ELISA reactions for as few as 10 to 15 calves from the fall calf crop of a given herd are sufficiently accurate to be used to assess F hepatica herd infection rates, the likelihood of liver condemnations at feedlot destinations, and variation between individual farms in fascioliasis infection risk. The test was less valuable as a diagnostic test when used in adult animals previously exposed to F hepatica or on an individual animal basis.

Animals↗
PubMed1986

Functional independence in quadriplegia: critical levels.

The purpose of this study was to examine the self-care abilities of individuals with quadriplegia at two critical functional levels, once they resumed community living. Twenty-nine individuals with quadriplegia (17 with wrist extensors as the lowest functional muscle and 12 with triceps), were surveyed three months to four years after discharge, to determine self-care independence and change in ability since discharge in ten self-care areas. Personal care assistance, use of equipment, and present living situation also were surveyed. Results indicated that subjects with triceps as the lowest functioning muscle had significantly greater independence levels in self-care activities than those with wrist extensors. Changes in abilities from discharge to follow-up were noted for both groups, especially in the areas of bowel and bladder care, dressing, and mobility activities. Most subjects lived at home with their family and used personal care assistance to accomplish part of their self-care. Equipment use was decreased upon community living for both groups. It is concluded that the functioning of triceps is a significant determinant for functional independence in self-care tasks.

Activities of Daily Living↗
PubMed1979

Decreased tetracycline bioavailability caused by a bismuth subsalicylate antidiarrheal mixture.

Oral coadministration of a single 250-mg tetracycline capsule and 60 ml of a bismuth subsalicylate antidiarrheal mixture reduced tetracycline absorption by 34% without appearing to perturb its absorption or disposition rate. A pronounced increase in intersubject tetracycline absorption variability also was noted. Apparently, the reduction in tetracycline bioavailability previously reported with a kaolin-pectin suspension is not peculiar to kaolin-pectin but can be expected with almost any antidiarrheal whose mechanism of action is adsorptive in nature.

Adult↗
PubMed1978

Pharmacokinetic evaluation of a drug interaction between kaolin--pectin and clindamycin.

The effect of a kaolin--pectin antidiarrheal suspension on the bioavailability of orally administered clindamycin was evaluated by model-dependent pharmacokinetic techniques. Each subject's serum clindamycin concentration--time data in the absence of the kaolin--pectin suspension were fitted to a one-compartment open model with first-order absorption and lag time. The resulting disposition parameters were used to construct individual Wagner-Nelson absorption profiles, expressed as the cumulative relative fraction of clindamycin absorbed versus time following combined antidiarrheal--antibiotic therapy. For each subject, absorption persisted to varying degrees through 14 hr. On the average, the half-time for absorption was prolonged 20-fold (from about 16 min to more than 300 min). In contrast, extrapolation of the individual time courses of relative absorption to infinity revealed that the antidiarrheal had no effect on the extent of clindamycin absorption.

Adult↗
PubMedDate not supplied

Prognostic value of a normal or nonspecific initial electrocardiogram in acute myocardial infarction.

CONTEXT: Although previous studies have suggested that normal and nonspecific initial electrocardiograms (ECGs) are associated with a favorable prognosis for patients with acute myocardial infarction (AMI), their independent predictive value for mortality has not been examined. OBJECTIVE: To compare in-hospital mortality among patients with AMI who have normal or nonspecific initial ECGs with that of patients who have diagnostic ECGs. DESIGN, SETTING, AND PATIENTS: Multihospital observational study in which 391 208 patients with AMI met the study criteria between June 1994 and June 2000 and had ECGs that were normal (n = 30 759), nonspecific (n = 137 574), or diagnostic (n = 222 875; defined as ST-segment elevation or depression and/or left bundle-branch block). A logistic regression model was constructed using a propensity score for ECG findings and data on demographics, medical history, diagnostic procedures, and therapy to determine the independent prognostic value of a normal or nonspecific initial ECG. MAIN OUTCOME MEASURES: In-hospital mortality; composite outcome of in-hospital death and life-threatening adverse events. RESULTS: In-hospital mortality rates were 5.7%, 8.7%, and 11.5% while the rates of the composite of mortality and life-threatening adverse events were 19.2%, 27.5%, and 34.9% for the normal, nonspecific, and diagnostic ECG groups, respectively. After adjusting for other predictor variables, the odds of mortality for the normal ECG group was 0.59 (95% confidence interval [CI], 0.56-0.63; P<.001) and for the nonspecific group was 0.70 (95% CI, 0.68-0.72; P<.001), compared with the diagnostic ECG group. CONCLUSION: In this large cohort of patients with AMI, patients presenting with normal or nonspecific ECGs did have lower in-hospital mortality rates than those of patients with diagnostic ECGs, yet the absolute rates were still unexpectedly high.

Aged↗
PubMedDate not supplied

The effect of colestipol hydrochloride on the bioavailability and pharmacokinetics of clofibrate.

Since it has been reported by several authors that colestipol HCl and clofibrate have an additive effect in lowering serum cholesterol levels, it was felt advisable to evaluate the blood levels of clofibrate when given simultaneously with colestipol HCl to see whether there was any evidence for drug interaction between the two products that might dictate a need for separation of their administration time. After concomitant single-dose administration, the serum p-chlorophenoxyisobutyric acid levels, bioavailability parameters, and pharmacokinetic parameters investigated provided no evidence for an interaction and suggested that colestipol and clofibrate can be administered concomitantly or at separated in tervals according to whichever dosage regimen is deemed advisable by the physician.

Adult↗
PubMedDate not supplied

Nifedipine overdose accompanied by ethanol intoxication in a patient with congenital heart disease.

A 34-year-old female was brought to the emergency department after taking 200 to 250 mg of nifedipine and drinking an unknown amount of ethanol in a suicide attempt. She was hypotensive, acidotic, mildly hyperglycemic, and exhibited a conduction abnormality on the ECG. The patient was treated with IV fluids, thiamine, and calcium infusion. The patient was later found to have an endocardial cushion defect with a patched ventricular septal defect and an atrial septal defect of the ostium primum type. We did not observe any untoward effects due to the combination of drugs and congenital abnormalities that could be explained on an individual basis. Nifedipine overdose associated with alcohol intoxication, to our knowledge, has not been previously reported.

Adult↗
PubMedDate not supplied

Axial characteristics of circular external skeletal fixator single ring constructs.

OBJECTIVE: Evaluate the effects of varying ring diameter, wire tension, and wire-divergence angle on the axial stiffness characteristics of circular external skeletal fixator single-ring constructs. Study Design-Biomechanical evaluation using circular fixator components and a Delrin cylinder bone model. METHODS: Single ring constructs using two 1.6 mm diameter Kirschner wires to secure a 19 mm Delrin cylinder centered within the ring were examined. Component variables evaluated were ring diameter (50 mm, 66 mm, 84 mm, and 118 mm), wire-divergence angle (30 degrees, 60 degrees, and 90 degrees ), and wire tension (0 kg, 30 kg, 60 kg, and 90 kg). A total of 48 constructs were examined. Rings were rigidly mounted on a universal testing system and the cylinder loaded in axial compression (7.4 N/s) to 220 N. Load/displacement curves were analyzed to determine the following: the displacement (mm) that occurred before the slope of each load/displacement curve became linear, the stiffness (N/mm) of the linear portion of each load/deformation curve, and the total displacement (mm) produced at maximal load. Least-squares linear regression was used to model response variables as linear functions of ring diameter, wire divergence angle, and wire tension. Three-way interactions and 2-way interactions among independent component variables were evaluated first in the modeling process and included in a best model if response variables were found to have statistically significant regression coefficients. The regression coefficients and corresponding standard errors and covariances were used to estimate the maximal effect and standard error attributable to wire divergency angle (change from 30 degrees to 90 degrees ) and wire tension (change from 0 to 90 kg) for each ring diameter. RESULTS: All load/deformation curves had an initial exponential increase in stiffness, with the slope becoming linear at higher loads. The exponential phase was more pronounced in larger-diameter ring constructs and was mitigated by tensioning the wires. Ring diameter had the greatest influence on displacement that occurred before the curve became linear (semipartial r(2) [sp-r2] = .89), stiffness (sp-r2 = .94), and total displacement (sp-r2 = .93). Wire tension exerted a smaller influence on displacement that occurred before the curve became linear (sp-r2 =.06), stiffness (sp-r2 = .03), and total displacement (sp-r2 = .05). Wire divergence angle had a nominal effect on displacement that occurred before the curve became linear (sp-r2 = .0001), on stiffness (sp-r2 = .004), and on total displacement (sp-r2 =.003). CONCLUSIONS: Ring diameter had a profound effect on the axial stiffness characteristic of single ring constructs. Tensioning of the fixation wires can improve the axial stiffness characteristics of these constructs, particularly in larger diameter ring constructs, by mitigating the initial exponential phase of the load/deformation curve. Wire divergence angle had only a nominal differential effect on axial stability. CLINICAL RELEVANCE: Understanding how individual component variables and their interactions influence bone segment stability should help surgeons to optimize interfragmentary strain. Tensioning fixation wires is probably unnecessary in 50 mm diameter ring constructs, but assumes greater importance as ring diameter increases.

Animals↗
PubMedDate not supplied

Arthroscopic approach and intra-articular anatomy of the palmaroproximal or plantaroproximal aspect of distal interphalangeal joints.

An arthroscopic approach to the palmaroproximal or plantaroproximal pouch of the distal interphalangeal joint was developed in six cadaver limbs and seven limbs of three clinically normal horses. The dorsal aspect of the proximal border and the proximal articular margin of the distal sesamoid (navicular) bone, the palmar aspect of the distal articular margin of the middle phalanx, the collateral sesamoidean ligaments of the distal sesamoid bone, and the joint capsule attachments were readily accessible. Distending the joints with fluid gave access to portions of the articular surface between the distal sesamoid bone and the middle phalanx in all joints, and to a small portion of the distal phalanx in two hind distal interphalangeal joints. Two horses allowed to recover from anesthesia were not lame on days 30 and 37, respectively. Problems encountered initially were difficulty entering the joint, hemarthrosis, and minimal iatrogenic cartilage damage.

Animals↗
PubMedDate not supplied

Septic arthritis of the distal interphalangeal joint in 12 horses.

The medical records of 12 horses with septic arthritis of a distal interphalangeal joint were reviewed to determine clinical features and response to treatment. Sepsis was caused by trauma or an injection that resulted in an open or contaminated distal interphalangeal joint. All horses were severely lame. Treatment included broad-spectrum parenterally administered antimicrobial drugs (ten horses), percutaneous through-and-through joint lavage (eight horses), indwelling drains (three horses), immobilization of the limb in a cast (three horses), intraarticular injection of sodium hyaluronate (one horse), intraarticular injection of antimicrobial drugs (five horses), curettage of the distal phalanx (one horse), and cancellous bone grafting to promote fusion (one horse). Five horses were euthanatized. Ankylosis of the affected joint developed in five horses, four of which are pasture sound. Two horses treated medically are sound although one underwent subsequent palmar digital neurectomy for treatment of navicular syndrome.

Animals↗
PubMedDate not supplied

Disseminated intravascular coagulation associated with colic in 23 horses (1984-1989).

Disseminated intravascular coagulation (DIC) secondary to colic was diagnosed in 23 horses. Each horse was categorized retrospectively as to the cause of the colic based on surgical and/or necropsy findings: group 1 consisted of 14 horses with compromised intestine that required resection and anastomosis; group 2 consisted of 3 horses with nonstrangulating intestinal displacement and/or impactions; and group 3 consisted of 6 horses with colic associated with enteritis and/or colitis. Horses were considered to be affected with DIC if at least three of five hemostatic parameters were significantly abnormal: decreased antithrombin III (AT III) values, increased level of fibrin degradation products (FDP), thrombocytopenia, prolonged activated partial thromboplastin time, and prolonged prothrombin time. The most consistent hemostatic abnormalities were decreased AT III activity, increased FDP titers, and thrombocytopenia. Clotting times were more variable and did not always correlate with the presence of excessive hemorrhage. Excessive hemorrhage was present during surgery in seven horses and occurred within 1 to 12 hours after surgery in nine other horses. In addition to treatment of the primary disease, 19 horses received treatment for DIC consisting of heparin and/or plasma or fresh whole blood transfusions. Heparin alone was used in 12 horses. Heparin, in addition to fresh whole blood transfusions or fresh plasma, was administered to four horses. Three horses were treated with plasma alone. Four other horses were not treated specifically for the DIC. Eight horses (34%) survived the acute coagulopathy. Although a greater proportion of the surviving horses received heparin therapy (87.5%; 7/8) than did those that died (60%; 9/15), the difference was not statistically significant (P = 0.345).(ABSTRACT TRUNCATED AT 250 WORDS)

Anastomosis, Surgical↗