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Biomedical subjects

S S Howards

Publications and source records attributed to S S Howards.

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

The venous anatomy of experimental left varicocele: comparison with naturally occurring left varicocele in the human.

OBJECTIVE: To determine the effect of experimental left varicocele on the anatomy of the veins serving the rat testis and to compare that anatomy to known patterns of vascular drainage from the human testis with and without varicocele. DESIGN: Vascular maps were made of the effluent vessels from the rat testis in control animals and those with a 30-day experimental left varicocele. Consensus maps were arrived at and these were compared to published reports of the pertinent venous anatomy in humans with and without varicocele. SETTING: Research laboratory. RESULTS: The major route of blood leaving the rat testis was confirmed to be the spermatic vein, but nine common collaterals were also found to exist. Four of these collaterals became more pronounced with experimental varicocele as did several dilated perineal veins. These latter vessels all led to the iliac vein. The vasculature of the rat experimental varicocele model shares some important anatomical features with human varicocele anatomy. CONCLUSIONS: Varicocele in humans and in the rat model causes a redistribution of blood flow from a route primarily out the spermatic vein to routes leading to the iliac vein. The redistribution is similar but not identical.

Animals↗
PubMed1994

Scrotal ultrasound for evaluation of subacute testicular torsion: sonographic findings and adverse clinical implications.

There is an increased use of scrotal ultrasound in the clinician's office and emergency room for the investigation of scrotal pain. The use of real-time scrotal ultrasound for the diagnosis of testicular torsion has been described in the literature. A false-negative ultrasound examination can postpone the diagnosis of torsion and result in testicular loss. We examined 6 patients 1 day to 18 years old who had subacute testicular torsion with scrotal symptomatology (pain and/or swelling) for longer than 8 hours (range 12 hours to 6 days). Scrotal ultrasound was performed as 1 of the initial tests. A common sonographic pattern was an inhomogeneous testicle with hypoechoic areas alternating with hyperechoic areas and thickening of adjacent scrotal tissue. Another common finding was an edematous hyperechoic epididymis and a small hydrocele. In 4 of the 6 cases these nonspecific findings suggested a misleading diagnosis of tumor or epididymitis and resulted in delay of surgery and testicular loss. Treatment was not delayed in only 2 patients in whom the diagnosis of torsion was made initially by history and physical examination, and ultrasound was done for interest only. Misdiagnosis of intratesticular blood flow and some potential pitfalls of scrotal imaging by color Doppler ultrasound are discussed. We conclude that real-time scrotal sonography can be misleading in cases of subacute testicular torsion and, therefore, it should not be used in this clinical setting.

Acute Disease↗
PubMed1994

Early antibody response following vasectomy is related to fertility after vasovasostomy in glucocorticoid-treated and untreated Lewis rats.

The influence of treatment with a glucocorticoid on antisperm antibodies and fertility after vasectomy and vasovasostomy was studied in Lewis rats. Animals received a bilateral vasectomy followed 4 weeks later by bilateral vasovasostomy. Treatment with methylprednisolone for two months beginning at the time of the vasovasostomy resulted in a decrease in antisperm antibodies compared with nontreated vasovasostomized animals, but there was no difference in fertility between treated and nontreated vasovasostomized groups. However, when fertile vasovasostomized animals from treated and nontreated groups were compared with infertile vasovasostomized animals, antisperm antibodies were found to be significantly lower in fertile rats 2, 4 and 8 weeks after vasectomy, while antibodies did not differ between fertile and infertile animals at the end of the study (12 weeks). The observation that differences in antisperm antibodies appeared shortly after vasectomy, preceding either vasovasostomy or treatment, suggests that changes occurring very early after vasectomy have far-reaching effects and are among the factors that influence future fertility after vasovasostomy.

Analysis of Variance↗
PubMed1994

The use of urea for dissolution of urinary mucus in urinary tract reconstruction.

Increased urinary mucus is common after urinary tract reconstruction involving the use of bowel segments. This mucus can prove troublesome when it interferes with emptying of the bladder reservoir, particularly in the prepubertal boy, in whom a small catheter must be be used. We report a rapidly effective, nontoxic, inexpensive method of dissolving urinary mucus by periodic instillation of a concentrated urea solution.

Child↗
PubMed1993

Ultrastructure of epididymal interstitial reactions following vasectomy and vasovasostomy.

The response of the male reproductive tract to vasectomy includes inflammation of the interstitial tissue of the epididymis. The pathogenesis of epididymal interstitial reactions and characteristics of the responding cells were studied by electron microscopy in Lewis rats at intervals following bilateral vasectomy, vasectomy followed 1 month later by vasovasostomy, or sham operations. In areas of interstitial reaction, numerous macrophages, monocytes, lymphocytes, neutrophils, and plasma cells occupied the connective tissue. Macrophages, containing many lysosomes and vesicles, aggregated and assumed the appearance of epithelioid cells. Processes of adjacent macrophages interdigitated with one another and closely approached the surfaces of lymphocytes. Many plasma cells with distended rough endoplasmic reticulum appeared in the interstitium. The majority of animals in the vasectomy and vasovasostomy groups exhibited epididymal interstitial changes by 2-3 months; the cauda epididymidis was the region most often affected. The ultrastructural features were indicative of chronic granulomatous inflammation and were consistent with an immune response that includes antigen presentation by macrophages to lymphocytes, lymphocyte differentiation, and local antibody production by plasma cells. The nearly complete absence of sperm or recognizable parts thereof in the interstitial tissue in the areas of the reactions suggests that these lesions formed in response to soluble antigens leaking from the duct. Vasovasostomy was not effective in reversing or retarding epididymal inflammation at the intervals studied.

Animals↗
PubMed1993

Spermatic cord torsion in an infant receiving human chorionic gonadotropin.

Human chorionic gonadotropin and gonadotropin-releasing hormone administration has been advocated for the nonoperative management of undescended testes. Proponents of hormonal manipulation cite the low morbidity of endocrine treatment as its major advantage over conventional surgical repair. We report a serious potential complication of human chorionic gonadotropin administration, intravaginal spermatic cord torsion and testicular infarction, in an infant with bilateral cryptorchidism.

Chorionic Gonadotropin↗
PubMed1993

Possible biological mechanisms for a relationship between vasectomy and prostatic cancer.

Four hypotheses have been reviewed, each of which might serve as a hypothetical biological explanation for a relationship between vasectomy and prostate cancer. The endocrine hypothesis is the only one of these with any firm data to support it, although the majority of the available data does not lend credibility to that theory. The other hypotheses are purely speculative with no hard data to support them. In conclusion, it seems highly unlikely, but not impossible, that there is a biological mechanism supporting a relationship between vasectomy and prostate cancer.

Androgens↗
PubMed1991

Injury to the pre-pubertal vas deferens. I. Histological analysis of pre-pubertal human vas.

There is very little information in the literature on the development of the human vas deferens. Therefore, the age at which the pre- or para-pubertal vas deferens becomes large enough for a vasovasostomy to be technically feasible is unknown. To determine the age or degree of sexual maturity at which a microscopic vasovasostomy is technically feasible, we collected surgical or autopsy vasa from 34 young males over a three year period, and correlated vasal size to age and Tanner stage (degree of sexual maturity ranging from 1-childhood to 5-adult). The specimens were embedded and sectioned transversely in glycol methacrylate. Using image analysis, the total transverse area and diameter, and luminal area and diameter was determined for each specimen. Surprisingly, there was no change in vasal size from birth up through 11 years. From age 15 years and on, the vas was adult in size. The vas develops to adult size between Tanner stages 2 and 3. The average external and luminal diameters of pre-midpuberty specimens (Tanner stages 1 and 2) were 1.0 and 0.19 (mm.) and the diameters of post-midpuberty specimens were 2.1 and 0.43 (mm.), respectively. These results suggest that, in the event of a recognized iatrogenic injury to the vas deferens after midpuberty, a repair by a traditional microsurgical vasovasostomy is possible. If the vas is injured before midpuberty it may be technically difficult to repair by traditional microsurgical methods.

Adolescent↗
PubMed1991

Injury to the pre-pubertal vas deferens. II. Experimental repair.

We have previously shown that the human vas deferens does not change in cross-sectional size between birth and the middle of puberty. This suggests that if the human vas is injured prior to mid-puberty, repair by a traditional microsurgical vasovasostomy may be technically difficult. We propose that a chromic stent can be used to assist in the repair of vas injured before mid-puberty. This hypothesis was tested in Sprague-Dawley rats. At three weeks of age, male offspring were divided into three groups (eight to nine rats/group): 1) Sham group--a sham operation at three weeks, 2) VV group--bilateral transection of vasa at three weeks followed by a delayed repair at eight weeks by microsurgical vasovasostomy without a stent, 3) Stent group--bilateral transection of vasa at three weeks followed by immediate repair by aligning the lumens with a 6-0 chromic intravasal stent (suture) and holding the transected ends together with several seromuscular sutures. At four months all rats were fertility tested and a score was given to each rat (mean number of concepti among three females for each male rat). Analysis of anastomotic patency by flow rates and histology was performed. There was no statistical difference in the mean fertility score of 6.85 in the Stent group compared to 7.83 in the Sham group. However, a fertility score of 0.71 in the VV group was significantly decreased compared to the Stent and Sham group (p = .0003), despite no statistical difference between the groups in patency. This suggests that a recognized injury to the pre-pubertal human vas should be immediately repaired and the repair can be done using 6-0 chromic suture as an intravasal stent to help align the lumina of the smaller pre-pubertal vas.

Animals↗
PubMed1991

Factors that influence fertility after vasovasostomy in rats.

OBJECTIVE: To determine if fertility after vasovasostomy of immunologically responsive Lewis rats differs from that of the less responsive Sprague-Dawley strain and to relate fertility to antisperm antibodies, fluid flow in the vas deferens, and testicular structure. DESIGN: Male rats received: (1) bilateral vasectomies; (2) vasectomies followed 3 months later by vasovasostomy; or (3) sham operations. SETTING: Research laboratory. MAIN OUTCOME MEASURES: Fertility was assessed by caging males with three females for 2 weeks and subsequently counting implantation sites. Antisperm antibodies were measured with an enzyme-linked immunosorbent assay, fluid flow through vas deferens segments was tested in vitro, and testicular structure was studied microscopically. RESULTS: Nearly all vasovasostomized Lewis rats were infertile (33 of 34), whereas 62% (18 of 29) Sprague-Dawley rats were fertile after vasovasostomy (P less than 0.001). In fertile Sprague-Dawley males, significant correlations existed between: (1) implantation sites or females impregnated; and (2) antisperm antibodies early after vasectomy, vas flow, and testicular morphology. CONCLUSIONS: Genetic differences affect fertility after vasovasostomy. Fertility after vasovasostomy is also influenced in a multifactorial manner by the immune response, mechanical elements, and structural changes in the reproductive tract.

Animals↗
PubMed1990

Early testicular changes after vasectomy and vasovasostomy in Lewis rats.

The testes of Lewis rats were studied at intervals from 2 weeks to 3 months after bilateral vasectomy, vasectomy followed 1 month later by vasovasostomy, or sham operations. Aims were to determine the nature of early alterations after vasectomy, and to determine whether vasovasostomy after 1 month would result in reversal of vasectomy-induced changes. Approximately one-fourth of the testes in the vasectomy and vasovasostomy groups displayed histological changes, which consisted mainly of depletion of germ cells. The extent of the depletion varied greatly in different seminiferous tubules. In testes altered in this way, no abnormal infiltrations of lymphocytes, macrophages, or other cells were observed in the seminiferous epithelium or in the interstitium. The rete testis and straight tubules were normal in testes with altered seminiferous epithelium. A few testes in the vasectomy and vasovasostomy groups had necrotic centers. The results suggest that depletion of germ cells occurred as a result of shedding from the seminiferous epithelium into the lumen of the tubules. A cellular immune response, such as occurs in experimental allergic orchitis in other species, did not appear to be responsible for the observed loss of germ cells. This suggests a possible role for humoral antibody in this model, since there is an association between testicular changes and serum antisperm antibodies at longer intervals after vasectomy. Testicular alterations were not reversed by performance of a vasovasostomy 1 month after vasectomy.

Animals↗
PubMed1990

Multicystic dysplastic kidney: natural history of prenatally detected cases.

To delineate the natural history of fetal multicystic dysplastic kidneys (MDKs), all cases that were prenatally detected in the Prenatal Diagnosis Center of the University of Virginia from September 1985 to 31 August 1988 were reviewed. All patients were followed through the Center with serial ultrasound evaluations at approximately 4-week intervals, and each liveborn infant was evaluated and followed by one of the authors (S.S.H.). Of the 14 cases detected, ten were detected in the second trimester, the earliest at 16.5 weeks' gestation. Of the nine fetuses with non-lethal disease, there were two cases in which the lesion remained unchanged during observation. Both had an initial diagnosis in the third trimester. In those cases diagnosed in the second trimester (7), all showed an initial increase in the size and number of cysts, followed by involutional changes either in utero (2) or in the neonatal period (3). Two infants had immediate surgical removal of the MDK, one because of respiratory compromise, and the other because of an uncertain diagnosis on renal scan. Abnormalities of the contralateral kidney were found in 7 of 14 fetuses. Five were lethal conditions. Associated non-renal abnormalities were common in bilateral MDK (80 per cent), but rare in unilateral MDK (11 per cent).

Female↗
PubMed1990

Acute torsion of a renal transplant: cause of organ loss.

Acute torsion of a renal allograft has not been previously described as a cause of organ loss. We present a case of acute torsion of a transplanted kidney in a patient with prune-belly syndrome which led to renal necrosis, necessitating organ removal.

Humans↗
PubMed1990

On the maintenance of male fertility in the absence of native testosterone secretion: site-directed hormonal therapy in the rat.

A method of direct percutaneous injection of testosterone (T)-laden microspheres directly into the testis was used in an attempt to achieve the maintenance of normal intratesticular T concentrations, spermatogenesis, and fertility. Rats were divided into three groups: (1) sham operated/injection controls; (2) animals receiving 250 micrograms/d gonadotropin-releasing hormone (GnRH)-antagonist; and (3) animals receiving GnRH-antagonist as in group 1 plus 20 mg T-laden microspheres/testis. Treatment periods were 45 and 90 days. Serum T, testicular interstitial fluid T, testis weights, epididymal weights, daily sperm production (sperm x 10(6)/g/d), cauda sperm motility, and fertility were assessed in all animals. Gonadotropin-releasing hormone antagonist treatment reduced serum and testicular interstitial fluid to below detectable levels at day 45 and to similar levels at day 90. Supplementation with T-laden microspheres maintained testicular interstitial fluid T at concentrations not different from controls without elevation of serum T concentrations. All other values, including fertility were suppressed by GnRH-antagonist treatment and maintained by supplementation with T-laden microspheres.

Animals↗