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Biomedical subjects

R Richardson

Publications and source records attributed to R Richardson.

At least 163 records · Page 9Linked to original sources
PubMed1979

Kinetics of Mg2+ flux into rat liver mitochondria.

Unidirectional fluxes of Mg2+ across the limiting membranes of rat liver mitochondria have been measured in the presence of the respiratory substrate succinate by means of the radioisotope 28Mg. Rates of both influx and efflux of Mg2+ are decreased when respiration is inhibited. A linear dependence of the reciprocal of the Mg2+ influx rate on the reciprocal of the Mg2+ concentration is observed. The apparent Km for Mg2+ averages about 0.7 mM. N-Ethyl-maleimide, an inhibitor of transmembrane phosphate-hydroxyl exchanges, enhances the observed pH dependence of Mg2+, influx. In the presence of MalNEt, the apparent Vmax of Mg2+ influx is greater at pH 8 than at pH 7, and there is a linear dependence of the Mg2+ influx rate on the external OH- concentration. The K+ analogue Tl+ inhibits Mg2+ influx, while La3+, an inhibitor of mitochondrial Ca2+ transport, has no effect on Mg2+ influx. Mg2+ competitively inhibits the flux of K+ into rat liver mitochondria. The mechanism(s) mediating mitochondrial Mg2+ and K+ fluxes appear to be similar in their energy dependence, pH dependence, sensitivity to Tl+, and insensitivity to La3+.

Animals↗
PubMed1978

A transepidermal chemotherapy of onchocerciasis.

Counts of microfilariae in the skin, and histological and electronmicroscopic procedures have been used to analyze the response of onchocerciasis patients to diethylcarbamazine citrate (DEC) given either orally or topically. Oral administration of DRC failed to eliminate all microfilariae. Transepidermal DEC resulted in rapid degeneration of microfilariae, and daily single applications of the drug greatly reduced or apparently eliminated microfilariae from the skin. Following weekly topical applications of a DEC emulsion, effective suppression of O. volvulus microfilariae in patients living in a hyperendemic area was maintained for many months; and the dermal pathology resolved.

Administration, Oral↗
PubMed1977

Unpredictability of theophylline saliva measurements in chronic obstructive pulmonary disease.

The use of saliva as an indirect, non-invasive method of theophylline plasma level measurement was evaluated in 23 older men with chronic obstructive pulmonary disease and numerous concurrent medical problems. Simultaneously collected plasma and saliva samples were obtained on two or more occasions and analyzed for theophylline concentration by the Schack and Waxler spectrophotometric method. The mean (+/- SD) plasma:saliva ratio for 84 sample sets was 1.6 (+/- 0.5) with the saliva concentration averaging 64.8% (+/- 20.8%) of the plasma concentration. Multiplying a randomly chosen plasma:saliva ratio from each patient by the saliva concentration of a second randomly selected observation resulted in a predicted plasma concentration that differed by more than 20% of the measured concentrations for 16 of the 23 patients. Thus, use of saliva theophylline measurements obtained by the Schack and Waxler method to adjust dosage regimens cannot be recommended in these patients.

Chronic Disease↗
PubMed1977

Myocardial uptake (rabbit) of six 99mTc-tagged pharmaceuticals and 85Sr after vasopressin-induced necrosis.

A new rapid method for producing myocardial necrosis in rabbits was developed, using percutaneous intramyocardial injection of vasopressin in peanut oil. The 15-min procedure resulted in a mortality rate of 15% and a success rate among surviving animals of 50%. When the lesions were 24 hr old, strontium-85 and a technetium-99m-tagged agent were injected intravenously simultaneously, and the animals were killed 1,6, and 24 hr later for tissue radioassay. Strontium-85 failed to accumulate appreciably in the lesions. Three bone-seeking technetium complexes (pyrophosphate, methylene diphosphonate, and imidodiphosphonate) produced lesion-to-normal myocardial ratios of 6,5, and 14, respectively, at 1 hr, and 20,30, and 33 at 6 hr. The ratios for 99mTc-glucoheptonate were only 2 at 1 hr and 4 at 6 hr, while the ratios of 99mTc-acetylcysteine and 99mTc-citrate were even lower.

Animals↗
PubMed1977

Gastric bezoar formation secondary to gastroparesis diabeticorum.

Diabetic autonomic neuropathy may result in delayed gastric emptying and gastric retention. A case of gastric phytobezoar formation that was secondary to diabetic autonomic neuropathy is reported. Greatly impaired gastric emptying was documented in this case by administration of a radiolabelled meal. Parenteral metoclopramide hydrochloride completely corrected the patient's gastric motility disturbance.

Autonomic Nervous System↗
PubMed1976

Propranolol and morphine.

The morphine blocking and anticonvulsant effects of propranolol were investigated in mice. Three different convulsant procedures (electroshock, pentylenetetrazol and thebaine) were used. In addition, LD50's of morphine after different doses of propranolol were done. Sotalol was used as a control drug to check which of the effects of propranolol could be regarded as due to beta blockade. Morphine LD50 in mice is not altered by pre-treatment with propranolol. The anticonvulsant characteristics of propranolol are different from those of sotalol, the former acting mainly on the tonic phase of the seizures. This study does not support the hypothesis that propranolol is a morphine antagonist but reinforces the idea that propranolol has definite central nervous system effects.

Animals↗
PubMed1976

Acute hemorrhagic cerebellar infarction following angiography.

Cerebellar infarction following cerebral angiography is an unusual complication. A case is reported. The patient's condition deteriorated with each diagnostic study. Improvement occurred after cerebellar decompression and evacuation of an intracerebellar hematoma.

Cerebellar Diseases↗
PubMed1975

Accuracy of ultrasound in diagnosing abdominal masses.

B-mode ultrasonography was performed in 246 patients with suspected abdominal masses over a seven-year period. In 105 (40 percent), the accuracy of ultrasonic diagnosis was evaluated surgically. Sonography was proven correct in 60 (57 percent) patients who had undergone operation. Among 141 patients who had not undergone operation and whose diagnoses were established by other means, ultrasonography agreed with the clinical diagnosis in 69 (31 percent). Ultrasound accuracy, as confirmed by operation, was highest for splenic masses (100 percent) and for aortic aneurysm (88 percent). Liver masses were correctly identified in 56 percent of patients and gallbladder lesions in 38 percent. While only a 48 percent accuracy was obtained in diagnosing pancreatic disease, 64 percent of all pseudocysts were localized. Ultrasonography correlated positively with operative findings in 56 percent of renal masses. Intraperitoneal abscess was accurately diagnosed in 61 percent of patients but retroperitoneal adenopathy in only 33 percent. Abdominal ultrasonography, while accurately diagnosing splenic and aortic masses, failed to identify approximately half of other mass lesions. Improved techniques hold promise of improving this diagnostic accuracy.

Abdomen↗