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Biomedical subjects

G Brock

Publications and source records attributed to G Brock.

At least 37 records · Page 2Linked to original sources
PubMed1994

Rat model for the study of penile erection: pharmacologic and electrical-stimulation parameters.

We report the use of a modified rat model for the study of the mechanisms of penile erection. In 92 Sprague-Dawley rats, the cavernous nerve was stimulated with different pulse intensities and frequencies, and the intracavernous pressure, time to maximal pressure and total duration of tumescence were measured. A maximal response was elicited at 20 pulses per second (pps) and 1.5 mA. Using this as 100%, we determined the relative pressure responses obtained with other frequencies: 5 pps, 57.3% (p = 0.007), 10 pps, 84.9% (p = 0.043); 30 pps, 99.5% (p = 0.832); 40 pps, 97.8% (p = 0.168); 50 pps, 90.9% (p = 0.021); 100 pps, 76.1% (p < 0.001). The time to maximal pressure varied with different frequencies, but was in all cases significantly different from the 20-pps response. Erection time during continuous cavernous nerve stimulation was significantly longer with frequencies below 20 pps (10 and 5 pps). In 30 rats, the physiologic response to intracavernous injection (0.03 ml) of acetylcholine, atropine, guanethidine, norepinephrine, phenylephrine, papaverine, terbutaline (intravenous also) and phentolamine was measured. Papaverine caused a dose-dependent rise in pressure; acetylcholine, atropine (a parasympathetic blocking agent) and guanethidine all had minimal effects. Phentolamine and norepinephrine increased systemic blood pressure, whereas phenylephrine decreased the intracavernous pressure in response to electrostimulation significantly.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1993

Nitric oxide synthase: a new diagnostic tool for neurogenic impotence.

Cavernosal biopsy specimens obtained from men undergoing penile surgery permitted determination of the diagnostic value of nitric oxide synthase in neurogenic impotence. In biopsy specimens obtained from 25 men, the presence of nitric oxide synthase (NOS), as shown by nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase staining, was determined in nerve fibers, smooth muscle, and sinusoidal endothelium. Positive staining for NOS correlated significantly (p < or = 0.001) with a clinical history of cavernous nerve integrity. In comparison, staining with protein gene product (PGP 9.5), an excellent general nerve stain, lacked any degree of specificity as an indicator of nerve status. NADPH diaphorase may provide important insight into the cavernous nerve integrity of the patient. This report is the first to describe histologic features of human cavernosal tissue biopsies that will allow the direct diagnosis of neurogenic impotence owing to cavernous nerve damage.

Amino Acid Oxidoreductases↗
PubMed1993

Pathophysiology of erectile dysfunction.

During the past decade, our knowledge of the hemodynamics, functional anatomy, neurophysiology, and neuropharmacology of erectile function has evolved substantially. The change of smooth muscle tone has emerged as a key factor in erection and detumescence. However, future studies are needed to elucidate the cellular and molecular basis of erectile physiology. With insight into normal physiology we will understand the pathologic process and be able to treat it.

Animals↗
PubMed1993

Peyronie's disease: a modified treatment.

We evaluated 93 patients with complaints of sexual dysfunction and evidence of Peyronie's disease. Duplex ultrasonography (10-MHz probe and 4.5-MHz pulsed Doppler test) in 87 enabled definition of their penile vascular response to an intracorporeal injection of a vasoactive agent. Vascular disease was present in 70 percent of the study population. Forty-four patients had a surgical procedure. Nineteen had plications using a simultaneous pharmacological erection, 3 had dermal grafts, and 3 with severe vascular disease had primary placement of a prosthesis. One patient underwent a single Nesbit procedure. In 18 patients, we incised the plaque and grafted a segment of the deep dorsal vein, using the expertise gained from penile venous surgery. In the vein-grafted patients, rapid return of suppleness of the penile shaft, use of only a single incision, and use of the patient's own tissue, with the possible beneficial effect of endothelial-derived substances (nitric oxide) decreasing the risk of hematoma below the graft, support our belief that this modified technique may be superior to those presently in common use.

Adult↗
PubMed1993

Intracavernous sodium nitroprusside: inappropriate impotence treatment.

On the basis of reports describing nitric oxide as a form of endothelium-derived relaxing factor and on our own experience with intracavernous use of nitric oxide-releasing substances in animal models, we undertook an approved human study of intracavernous sodium nitroprusside as a treatment for impotence. We report our early experience in which severe hypotension and only mild tumescence in our first 3 patients caused us to discontinue the trial.

Aged↗
PubMed1993

High flow priapism: a spectrum of disease.

We describe 4 cases of high flow arterial priapism, ranging from 1 week to 3 years in duration. The mode of presentation, evaluation using a duplex scanner, treatment and ultimate resolution are discussed. In 1 patient treated with ice compression the erection subsided spontaneously. One patient underwent percutaneous embolization and achieved detumescence. In 2 men a vascular pseudocapsule formed around the site of the ruptured cavernous artery that provided an important anatomical landmark for intraoperative localization. The ruptured branch of the cavernous artery was ligated in an open procedure. Based on these cases and a review of the literature, we outline a modified diagnostic and therapeutic approach for patients with high flow arterial priapism.

Adolescent↗
PubMed1993

Can a venous patch graft be a substitute for the tunica albuginea of the penis?

We describe our experience with plaque excision and placement of a venous patch graft. Sprague Dawley rats (n = 20) underwent excision of a wedge of tunica albuginea with the defect covered by a segment of detubularized femoral vein, endothelial side towards the cavernous tissue. Erectile function, as determined by the rise in intracavernous pressure with cavernous nerve stimulation (mean 54.0 +/- 4.2 cm. H2O), was equal to that in a group of 10 intact age-matched controls (mean 46.9 +/- 3.37 cm. H2O). Penile cross-sections stained with Hart's elastic fiber stain or Trichrome stain revealed only minimal fibrosis in the region of the patch. In 3 dogs, a wedge of tunica was removed, and the defect was covered with a segment of detubularized deep dorsal vein. When sacrificed at 3 months, all animals had retained their erectile function with histologic evidence of minimal fibrosis. On the basis of histologic and functional data, the venous patch appears to be a reasonable alternative substance to those in common use.

Animals↗
PubMed1993

Denial among cancer patients. Tips and traps.

The coping mechanisms used by patients diagnosed with cancer play a role in their well-being and, therefore, influence their quality of life and possibly even their survival. We review the characteristics of one of these mechanisms, denial, and suggest an approach to dealing with denying patients.

Adaptation, Psychological↗
PubMed1993

Sodium nitroprusside and neurostimulation cause increased levels of cyclic guanosine monophosphate and not cyclic adenosine monophosphate during canine penile erection.

We investigated the changes of cGMP and cAMP during penile erection induced by direct electrical stimulation of the pelvic nerve or sodium nitroprusside administration. Immediately after penile erection, the samples were put into liquid nitrogen and cyclic nucleotide content was measured. The results of these investigation suggest that both pelvic nerve stimulation and sodium nitroprusside induced penile tumescence. The total content of cGMP and not cAMP were significantly higher in treated samples as compared to control. SDS-polyacrylamide gel electrophoresis revealed several differences after treatment compared to untreated samples. This study demonstrated that the total content of cGMP and not cAMP increased after pelvic nerve stimulation and sodium nitroprusside treatment in penile tissue.

Animals↗
PubMed1992

A real-time approach to spoken language processing in aphasia.

The study is based on an on-line investigation of spoken language comprehension processes in 25 French-speaking aphasics using a syllable-monitoring task. Nonsense syllables were presented in three different conditions: context-free (embedded in strings of nonsense syllables), lexical context (where the target nonsense syllable is the initial, medial, or final syllable of real three-syllable words), and sentence context. This study builds on an earlier one that explored the relationship between the acoustic-phonetic, lexical, and sentential levels of spoken language processing in French-speaking normals and gave evidence of top-down lexical and sentential influence on syllable recognition. In the present study, aphasic patients from various diagnostic categories were classified as high (N = 13) or low (N = 12) comprehenders. The results show that low comprehending aphasics make no use of sentence information in the syllable-recognition task. As for top-down effect at the single word level that is observed in normal listeners. However, a subgroup analysis shows that the Broca's are the only high comprehending aphasics who perform in the same way as normal listeners; this sets them apart from the anomics and conduction aphasics.

Adult↗
PubMed1991

Liturgical ministry to the sick: an overview.

Samples the rites and liturgies available to contemporary caregivers and notes particularly the current liturgical renewal having many implications for the hospital chaplain and pastoral counselor.

Chaplaincy Service, Hospital↗