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Biomedical subjects

L Ross

Publications and source records attributed to L Ross.

At least 91 records · Page 5Linked to original sources

Sentence reception in noise from one versus two sources: effects of aging and hearing loss.

Sentence reception thresholds (SRTs) and babble detection thresholds (BDTs) were measured for signals presented from loudspeakers located at 0 deg and 90 deg azimuth. In addition, the S/B ratios necessary to achieve SRT in the presence of a 12-talker babble were determined under three conditions in which the speech and babble were presented from the same or spatially separated loudspeakers. In the first experiment, normal-hearing subjects were tested on two occasions. The results were highly reliable, with standard errors of the test-retest differences of less than 1dB for all conditions. In the second experiment, SRTs, BDTs, and S/B ratios were measured for three normal-hearing groups (less than or equal to 39, 40-54, and greater than or equal to 55 years) and for a fourth group with presbycusis (greater than or equal to 55 years). Presbycusics had higher SRTs and BDTs than all other groups regardless of age, and the oldest normals had higher thresholds than younger subjects. Presbycusics required higher S/B ratios than any of the normal groups, and the oldest normal group needed a higher S/B ratio compared to the youngest group. All groups demonstrated a significant advantage in S/B ratio when the sentences and babble sources were spatially separated compared to when they were presented from the same loudspeaker. There was no significant difference in the magnitude of advantage due to spatial separation of speech and noise between the normal groups regardless of age, but the presbycusics had significantly smaller advantages than all normals.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Long-term effects of monaural, binaural and no amplification in subjects with bilateral hearing loss.

This study expands upon our earlier work by comparing initial PB scores and audiometric thresholds with results obtained 4-17 years later for subjects with bilateral sensorineural hearing losses who were monaurally aided (n = 48), binaurally aided (n = 19), or unaided (n = 19). Thresholds decreased slightly for all groups, but aided and unaided ears did not differ significantly in this respect, revealing no acoustic trauma effect due to hearing aid use. PB scores decreased significantly only for the unaided ear of the monaurally aided subjects, but not for their aided ear, or for the binaurally aided or unaided groups. These findings suggest an auditory deprivation effect for the unaided ear of those wearing a monaural hearing aid. Changes in PB scores were not correlated with duration between the two test dates. Changes in PB scores were correlated with degree of hearing loss only for the unaided group.

Adult↗

Diagnosis and management of testicular sarcoidosis.

We report testicular sarcoidosis in a patient who had known systemic involvement with this disease. The literature is reviewed and a protocol is presented to delineate specific indications for biopsy rather than orchiectomy to preserve testicular function.

Adult↗

Persistence of inaccurate beliefs about the self: perseverance effects in the classroom.

The perseverance of erroneous self-assessments was examined among high school students. Subjects were first exposed to either highly effective or thoroughly useless filmed instruction, leading, respectively, to their consequent success or failure. No-discounting subjects received no assistance in recognizing the relative superiority or inferiority of their instruction. Discounting subjects, by contrast, were subsequently shown the opposite instructional film, highlighting the obvious differences in instructional quality. Subsequent measures revealed that all subjects recognized the effectiveness or ineffectiveness of their instruction, although this contrast was clearer for discounting subjects. Nevertheless, both discounting and no-discounting subjects continued to draw unwarranted inferences--in line with their initial outcomes--about their personal capacities, immediately afterward. Dissociated and disguised measures of academic preferences and perceptions completed weeks later produced even more dramatic results: The continuing impact of initial outcomes was generally greater for discounting than no-discounting subjects.

Achievement↗

Urban cats: characteristics and estimation of mortality due to motor vehicles.

The present study was undertaken to characterize and estimate cat mortality caused by motor vehicles in Baltimore, Md. Analysis of Municipal Animal Shelter records revealed that the number of dead cats annually removed from Baltimore streets averaged 2,721 over 3 years. The number of cats removed per year was notably constant (range 2,621 to 2,917), with a consistently greater number of animals being picked up during summer months. A map of the location of 634 dead cats removed from city streets showed that areas of highest cat mortality were associated with areas of highest human population density. This map was used to stratify Baltimore into areas of high, medium, and low cat mortality for subsequent stratified random placement of tagged dead cats for the mark-recapture study. One hundred fifteen tagged dead cats were placed on city streets during the course of 1 year, and 50.5% were retrieved by the Municipal Animal Shelter. We estimate over 5,000 free-ranging cats are killed by automobiles/year in Baltimore. Analysis of 212 dead cats removed from city streets showed that the majority were male (63%) and that most animals were sexually intact (90%). At least 20% of the dead animals was previously owned, and few kittens or juvenile cats were found in the sample.

Accidents, Traffic↗

The hostile media phenomenon: biased perception and perceptions of media bias in coverage of the Beirut massacre.

After viewing identical samples of major network television coverage of the Beirut massacre, both pro-Israeli and pro-Arab partisans rated these programs, and those responsible for them, as being biased against their side. This hostile media phenomenon appears to involve the operation of two separate mechanisms. First, partisans evaluated the fairness of the media's sample of facts and arguments differently: in light of their own divergent views about the objective merits of each side's case and their corresponding views about the nature of unbiased coverage. Second, partisans reported different perceptions and recollections about the program content itself; that is, each group reported more negative references to their side than positive ones, and each predicted that the coverage would sway nonpartisans in a hostile direction. Within both partisan groups, furthermore, greater knowledge of the crisis was associated with stronger perceptions of media bias. Charges of media bias, we concluded, may reflect more than self-serving attempts to secure preferential treatment. They may result from the operation of basic cognitive and perceptual mechanisms, mechanisms that should prove relevant to perceptions of fairness or objectivity in a wide range of mediation and negotiation contexts.

Hostility↗

Single-strand breakage of DNA in UV-irradiated uvrA, uvrB, and uvrC mutants of Escherichia coli.

We transduced the uvrA6, uvrB5, uvrC34, and uvrC56 markers from the original mutagenized strains into an HF4714 background. Although in the original mutagenized strains uvrA6 cells are more UV sensitive than uvrB5 and uvrC34 cells, in the new background no significant difference in UV sensitivity is observed among uvrA6, uvrB5, and uvrC34 cells. No DNA single-strand breaks are detected in UV-irradiated uvrA6 or uvrB5 cells, whereas in contrast a significant number of single-strand breaks are detected in both UV-irradiated uvrC34 and uvrC56 cells. The number of single-strand breaks in these cells reaches a plateau at 20-J/m2 irradiation. Since these single-strand breaks can be detected by both alkaline sucrose and neutral formamide-sucrose gradient sedimentation, we concluded that the single-strand breaks observed in UV-irradiated uvrC cells are due to phosphodiester bond interruptions in DNA and are not due to apurinic/apyrimidinic sites.

Centrifugation, Density Gradient↗

Frequency of androgen insensitivity in infertile phenotypically normal men.

In 1979 Aiman and associates reported on a group of phenotypically normal men with severe oligospermia or azoospermia and androgen receptor deficiency. They calculated an androgen insensitivity index (ng./ml. serum testosterone times mIU/ml. serum luteinizing hormone) to identify these men and found the mean to be 233. We calculated the androgen insensitivity index in 144 infertile male patients in our fertility clinic. Of these patients 86 had azoospermia or severe oligospermia (mean sperm concentration 3 million per ml.). In this group 11.6 per cent had an androgen insensitivity index of more than 200, suggesting androgen insensitivity. These patients were compared to a control group with known fertility (16 semen donors) and to 34 men with idiopathic infertility (mean sperm concentration 47 million per ml.) treated with clomiphene citrate. The androgen insensitivity index may help to identify a group of 10 per cent or more of azoospermic or oligospermic men who are not amenable to therapy.

Clomiphene↗

Development of beta-adrenergic receptors and the in vitro accumulation of cyclic AMP in the chick spinal cord.

To clarify the functional development of the descending monoaminergic input to the chick spinal cord we have studied the ontogeny of beta-adrenergic receptors by measuring the specific binding the tritiated dihydroalprenolol (DHA). In addition, we examined the ability of isoproterenol to stimulate the accumulation of cyclic AMP in slices of developing chick spinal cord. Results show that the chick spinal cord contains a high density of beta-adrenergic receptors that are apparently linked to adenylate cyclase. During development, both the density of beta-receptors, as determined by the specific binding of DHA, and the response of tissue slices to isoproterenol underwent marked changes. beta-Adrenergic receptors (approximately 4 fmol/mg tissue) were first detected on the fourteenth day in ovo. Receptor density increased to approximately 20 fmol/mg by day 20. Between day 20 and the time of hatching, a sharp increase in receptor density, to approximately 50 fmol/mg, was seen. The density of receptors remained high until the second day after hatching, fell off to approximately 30 fmol/mg by the fourth day, and remained relatively unchanged through day 30. The response of spinal cord slices to isoproterenol showed a similar pattern of development with the peak response (7-fold increase in levels of cyclic AMP) occurring at or near the time of hatching. During the period between day 18 in ovo and the time of hatching, when both the response of tissue slices to isoproterenol and the density of beta-receptors increased markedly, the activity of phosphodiesterase did not change. Therefore, the pronounced changes in adrenergic responsiveness that occurred near the time of hatching appear to be related primarily to changes in the density of beta-adrenergic receptors coupled to adenylate cyclase. Such developmental changes in the density of beta-adrenergic receptors and adrenergic responsiveness may play an important role in determining the functional state of the descending monoaminergic systems in the chick spinal cord.

Adenylyl Cyclases↗

Subacute cutaneous lupus erythematosus and porphyria cutanea tarda. Report of a case.

Porphyria cutanea tarda (PCT) and various types of lupus erythematosus (LE) have been reported in the same patient on several occasions. In a large group of patients with PCT reported by Grossman et al, systemic lupus erythematosus (SLE) was found in two. Possibly LE is more common in patients with PCT; however, the mechanisms behind this coexistence are still unknown. The concurrent of PCT and subacute cutaneous lupus erythematosus (SCLE), as described by Sontheimer et al, has not been reported in previous patients. We are reporting a case of SCLE and PCT which has multiple complications in the course and therapy of these disorders.

Female↗

Physiologic effects of prazosin HCl: consequences of diuretic combination therapy.

The physiologic action of prazosin in man was studied in 23 patients including 10 treated with prazosin plus polythiazide. Responders to prazosin alone (blood pressure fell greater than 10 mm Hg) had a decrease in peripheral resistance (p less than 0.02) and no significant change in plasma volume, while nonresponders' plasma volume rose significantly (p less than 0.02). 10 patients treated with prazosin and polythiazide (blood pressure not normalized on prazosin alone) were analyzed at baseline (Rx 0), after prazosin (Rx 1), and after prazosin plus polythiazide (Rx 2). Mean supine blood pressure fell from 184/118 +/- 8/5 (SE) mm Hg at Rx 0 to 161/106 +/- 7/4 mm Hg at Rx 1 (p less than 0.005) and 129/89 +/- 4/4 mm Hg at Rx 2 (p less than 0.001). Supine renin increased in each group, but the increase with prazosin alone was not significant. Stimulated renin activity increased significantly after Rx 2 (p less than 0.0025). Cardiac output fell, plasma volume returned to baseline values, and peripheral resistance fell by 467 dyn s/cm-5 during thiazide treatment (p less than 0.025).

Adult↗

Candidal splenic abscesses complicating acute leukemia of childhood treated by splenectomy.

Two patients with acute leukemia were found to have candidal splenic abscesses. Both patients were in remission and had normal granulocyte counts at the time the abscesses became evident. Both patients were treated with splenectomy and antifungal therapy with a definite response. The incidence and treatment of fungal splenic abscesses in leukemia patients is discussed with emphasis on the role of splenectomy.

Abscess↗

Animal bites.

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Adolescent↗

Disc-electrophoretic separation of water soluble proteins from scales of different forms of ichthyosis.

In extracts of scales of different forms of ichthyosis, disc-electrophoretic separation of water soluble proteins was performed. Number and position of the protein bands correspond with number and position of the bands of extracts of normal keratin and psoriatic scales. However, in comparison to normal keratin, all examined forms of ichthyosis showed in zone II the enriched bands Nos. 6 and 7. This permits a distinct differentiation from psoriasis in which in zone II the bands Nos. 9 and 10 are enriched. In congenital ichthyosiform erythroderma and in ichthyosis combined with atopic dermatitis, in zone III the bands, containing gamma globulins, are enriched as an expression of the concomittant exudative process. The protein content of scale extracts of ichthyosis is 2 to 5 times lower than the one of psoriasis.

Dermatitis, Atopic↗

Varicocelectomy and infertility.

Eighty males with varicocele underwent internal spermatic vein ligation as therapy for infertility. Semen quality improved in 78 per cent following ligation, and 51 per cent of wives became pregnant. The results in this series compare favorably with previous studies. We believe that spermatic vein ligation is a very successful adjunct in the treatment of the infertile male with varicocele.

Humans↗