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Biomedical subjects

B Brown

Publications and source records attributed to B Brown.

At least 289 records · Page 16Linked to original sources
PubMed1983

Effects of luminance on contrast sensitivity in senile macular degeneration.

Patients with senile macular degeneration (SMD) often have difficulties in adapting to changing luminance levels. They may complain of problems at both high and low luminance levels, although some patients have their vision function markedly improved at high luminance levels. We examined the effect of luminance on the contrast sensitivity function in six patients with SMD and five normals of approximately the same age. The contrast sensitivity of the SMD patients compared to the control subjects was reduced at 72 cd/m2 but was comparable to that of the controls at 0.007 cd/m2. The peak of the contrast sensitivity function was moved to lower spatial frequencies at all luminances in the SMD group, and the slope of the function relating contrast sensitivity to luminance was reduced. These data suggest that adaptation mechanisms which optimize contrast detection are disrupted in SMD. Further disturbances of function might be expected in the dynamics of the adaptation process.

Adaptation, Ocular↗
PubMed1983

Cis-platinum ototoxicity: clinical experience and temporal bone histopathology.

A clinical and pathologic study of cis-platinum ototoxicity was performed. Twenty-four patients treated with cis-platinum for head and neck cancer were studied prospectively. Post cis-platinum hearing losses were subclinical, detected in 25% of patients, isolated to 4 and 8 kHz, and did not exceed 25 dB at any frequency. Temporal bones from a 9-year-old with frontal lobe astrocytoma and with cis-platinum ototoxicity were studied with routine and special techniques to elucidate oto and neurotoxicity. Degenerative changes in the outer hair cells in the lower turns of the cochlea, in the spiral ganglion, and cochlear nerve were the most striking findings.

Adult↗
PubMed1983

An endogenous digoxin-like substance in patients with renal impairment.

Digoxin concentrations were measured in serum samples from 102 patients with renal impairment who were receiving digoxin therapy. Many patients had values that differed widely on several currently available immunoassays, with differences as great as 2.9 ng/mL. In contrast, patients with normal renal function who were receiving digoxin had few discrepant results, with the largest difference being 0.5 ng/mL. We also assayed serum samples from 54 patients with renal impairment not on digoxin therapy and found that more than 60% of these digoxin-free patients had false-positive digoxin values on most assays. Our data suggest that a substance with digoxin-like immunoactivity is present in many patients with renal insufficiency. This substance may seriously compromise the accuracy and interpretation of digoxin concentration measurements.

Creatinine↗
PubMed1983

Clinical and subclinical oculomotor findings in the Eaton-Lambert syndrome.

Five patients with the Eaton-Lambert syndrome were examined neuro-ophthalmologically. Three were studied using electro-oculographic saccadic velocity recordings. Four complained of blurred vision and all complained of ptosis during the course of their disease. Clinical examination revealed mild ptosis in three of the five patients. Saccadic velocities before exercise were normal. After saccadic exercise, an increase in velocity of up to 40% was noted in two of the three patients studied.

Aged↗
PubMed1983

Renal effects of methoxyverapamil in anesthetized rats.

The purpose of these experiments was to determine the renal effects of methoxyverapamil (D-600). Three groups of rats were anesthetized with sodium pentobarbital and given 0, 0.85 or 1.69 nmol/min of methoxyverapamil i.v. Increases in urine flow and Na, K and Ca excretory rates occurred, in an apparently dose-dependent manner. Plasma Na and arterial renin concentration decreased at both doses and, at the higher dose, mean arterial blood pressure and effective renal plasma flow decreased while plasma K increased. Plasma Ca, glomerular filtration rate, filtration fraction and total renal plasma flow were not affected. The findings that methoxyverapamil increased urine flow and electrolyte excretion without changing glomerular filtration rate are consistent with the hypothesis that methoxyverapamil acts directly on tubular reabsorptive mechanisms. These effects, and the effect on plasma renin concentration, could contribute to the beneficial effects of this and other Ca entry antagonists in the treatment of hypertension.

Anesthesia, Intravenous↗
PubMed1983

Time course and variability of dark focus.

When the eye is deprived suddenly of visual stimulation, the accommodative system drifts from the previous state of accommodation to a state known as the dark focus. This condition also is known as night myopia. We measured the time course of this drift using a continuously recording infra-red optometer. The time course resembles an exponential decay function with a time constant of 1-3 seconds. The recovery of accommodation to the prior level after visual stimulation is restored suddenly has a time constant of 0.2-0.4 seconds. The state of accommodation in the dark depends on the state of accommodation prior to the onset of darkness. Our subjects showed a zone of accommodative inactivity rather than a single resting point of accommodation.

Accommodation, Ocular↗
PubMed1983

The effects of hemoglobin supplements on maximal oxygen uptake in females.

There was no significant change in the maximal oxygen uptake for either the experimental or the control group from the pre-test to the post-test. Five blood chemistry measures were unable to predict the post-maximal oxygen uptake scores using the procedure of stepwise regression. An examination of the blood chemistry profiles indicated that sports anemia did not occur. The factorial breakdown was unable to produce any significant insight into the changes in hemoglobin concentration and oxygen consumption. Heme-iron supplementation was unable to override the regulatory system of the body and allow the hemoglobin level to become elevated.

Adult↗
PubMed1983

The effect of phenylephrine hydrochloride on the resting point of accommodation.

Previous models for ocular accommodation have suggested a dual sympathetic/parasympathetic innervation to the ciliary muscle. Such models would predict that sympathomimetic drugs should change the resting point or dark focus of accommodation. The effect of an alpha-adrenergic agonist (10% phenylephrine hydrochloride) on accommodation was examined; the results show a decrease in the near point of accommodation, without a change in the resting point of accommodation. These results suggest that the accommodative state of the eye is not the result of a simple balance between sympathetic and parasympathetic innervation as proposed by previous models of accommodation.

Accommodation, Ocular↗
PubMed1982

Pseudorheumatoid nodule involving the orbit.

We report a clinicopathologic study of an unusual case of pseudorheumatoid nodule involving the right orbit of a child. Pathologically, the orbital lesion was similar to subcutanous nodules of rheumatoid arthritis and rheumatic fever. The physical findings and laboratory studies in our case did not reveal any evidence of systemic disease. Based on a review of reported cases involving other locations, this lesion appears clinically benign in children.

Child↗
PubMed1982

Aspergillus osteomyelitis. Report of four cases and review of the literature.

Four cases of Aspergillus osteomyelitis are presented and the world literature is reviewed, for a total of 19 cases. Aspergillus osteomyelitis is largely a disease of immunosuppressed hosts, although wound and other infections in "normal" hosts are seen. In children, contiguous spread from an adjacent pulmonary infection is most common, whereas in adults hematogenous spread is the rule. The survival rate in immunocompromised patients is poor, whereas the cure rate is uniform in "normal" hosts. A combined medical-surgical therapeutic approach has been used most often and seems appropriate.

Acetabulum↗
PubMed1982

Water intake after stomach loads of NaCl in 30-, 40-, and 50-day-old Mongolian gerbils.

Ninety Mongolian gerbils (Meriones unguiculatus), 15 male and 15 female in each of three age groups (30-, 40-, and 50-day-old), were stomach loaded with either water, 6% NaCl, or 12% NaCl (wt./vol.). No differences were observed in fluid intake or in body weight 24 hours after the load. These data were totally unlike the findings in rats. The lack of intergroup differences were probably attributable to the gerbil's unusual adrenal and kidney structure and hormonal controls.

Aging↗
PubMed1982

Effects of polyethylene glycol on water or saline intake in 30- and 50-day-old Mongolian gerbils.

Sixty 30-day-old male and female gerbils and sixty 50-day-old male and female gerbils were injected subcutaneously with either a .9% NaCl vehicle, 10% polyethylene glycol (P.G.), or 30% P.G. and given access to either water or .9% NaCl to drink. The .9% NaCl vehicle and the 10% P.G. injections were ineffective in increasing fluid intake. The Ss in the 30% P.G. injection level showed an increase in intake when saline was offered but did not increase their intake when water was the only solution available. The results are discussed in terms of compensatory mechanisms which subserve osmoregulation.

Aging↗