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Biomedical subjects

J M Hutson

Publications and source records attributed to J M Hutson.

At least 91 records · Page 5Linked to original sources
PubMed1997

Exogenous calcitonin gene-related peptide can induce the testis to cross the scrotal septum.

OBJECTIVES: To determine: (i) whether the pattern of gubernacular migration can be changed by local injections of calcitonin gene-related peptide (CGRP) in rats with a normal testicular position, (ii) the effects of both endogenous and exogenous CGRP on contralateral gubernacular migration and (iii) whether the scrotal septum acts as a barrier to prevent gubernacular migration. MATERIALS AND METHODS: Four groups of neonatal rats were used, all of which underwent right orchidectomy with: group 1 (29 rats) division of the genitofemoral nerve (GFN) on both sides; group 2 (31 rats) division of the left GFN; group 3 (31 rats) division of the left GFN and injections of oil into the right hemiscrotum; and group 4 (34 rats) division of the left GFN and injections of CGRP into the right hemiscrotum. After 26-38 days, the rats were killed and the testicular positions determined. RESULTS: In rats receiving no injections (groups 1 and 2), the testes were oriented further to the right side where the right GFN was not divided (group 2). With the addition of oil into the right hemiscrotum where the right GFN was not divided (group 3), the testes were oriented further to the left compared with those in group 2. Injections of CGRP into the right hemiscrotum in the presence of an intact right GFN (group 4) resulted in more testes where the axis was orientated to the right side of the scrotum compared with the other groups with an intact right GFN (groups 1 and 3) but this was not reflected in the mean distance from the midline, which was similar among these groups. A significant number of testes in groups 1, 2 and 4 crossed the midline. CONCLUSIONS: The presence of an intact GFN on the right side where the left nerve was divided provides a directional signal influencing migration of the contralateral gubernaculum to the right side of the scrotum. Oil injected into the scrotum interferes with the normal concentration gradient of CGRP released from the right GFN, resulting in gubernacular migration further toward the left side. CGRP injections were poorly localized to the right hemiscrotum, resulting in gubernacular migration toward in some and away from the site of injection in others. The midline scrotal septum is not a barrier to gubernacular migration and most likely forms as a secondary event following descent of the testis.

Animals↗
PubMed1997

Genital anomalies in human and animal models reveal the mechanisms and hormones governing testicular descent.

A systematic examination of the conditions characterized by the presence of genital anomalies in humans, noting in each condition the position of the gonad, the nature of the gubernaculum and cranial suspensory ligament can provide valuable information regarding the mechanisms controlling the final position of the gonads. In conditions where MIS is absent, the gubernaculum is "feminized', resulting in a testis in the position normally occupied by an ovary or an abnormally mobile testis that can prolapse to the inguinal region. In conditions of androgen insensitivity the testis is located in the inguinal region, indicating that the first phase of descent is normal but that inguinoscrotal descent has failed to occur. Ovarian descent fails to occur in congenital adrenal hyperplasia, despite exposure of the developing fetus to high levels of androgens, indicating that androgen alone does not control gonadal descent. Moreover, ovarian descent fails to occur despite androgen-dependent regression of the cranial suspensory ligament. The correlation between the degree of Müllerian duct retention and scrotal position in mixed gonadal dysgenesis further strengthens the hypothesis that the first stage of testicular descent is controlled by MIS. The study of genital anomalies suggests that MIS controls the swelling reaction in the male gubernaculum, which is responsible for the first phase of testicular descent to the inguinal region. The second or inguinoscrotal phase of descent is androgen-dependent. Regression of the cranial suspensory ligament is also androgen-dependent: however, it is the gubernaculum and not the presence or absence of the cranial suspensory ligament which controls testicular descent. A combined knowledge of the hormonal basis controlling sexual differentiation and the biphasic model of testicular descent enables the clinician to accurately predict the internal anatomy of these complex sexual anomalies.

Androgens↗
PubMed1997

Anatomical landmarks of the inguinal canal in prepubescent children.

BACKGROUND: Most adult anatomical texts state that the deep inguinal ring is situated midway between the anterior superior iliac spine and the pubic tubercle. The aim of this study was to determine if this was true in prepubescent children. METHODS: A total of 107 inguinal ligaments and canals were measured during inguinal operations in 80 children (68 boys, age range 1-118 months). RESULTS: The length of the inguinal ligament increased from a median of 4.3 cm (range 3.6-6.8) at less than 1 year of age to 7.5 cm (range 6.7-10.1) at over 4 years of age. The internal ring was situated medial to the midpoint of the inguinal ligament throughout childhood. The ratio of internal ring to public tubercle over inguinal ligament length was 42% (range 27-58) at less than 2 years; and 34% (range 25-46) at over 4 years. The inguinal canal remained short (median 1 cm (range 0.7-1.1) at less than 2 years, and median 1.1 cm (range 0.7-2.3) at over 4 years) suggesting that growth of the inguinal region in this age group occurs outside the canal. CONCLUSIONS: These results have implications for the siting of incisions, and question the necessity of opening the inguinal canal in children.

Adult↗
PubMed1997

Incomplete disappearance of the processus vaginalis as a cause of ascending testis.

PURPOSE: Recently evidence has been accumulating that some undescended testes present later in childhood after apparent normalcy in infancy. These ascending testes appear to explain why a significant number of orchiopexies are performed later in childhood despite the recommendation that surgery for cryptorchidism be performed in infancy. We aimed to determine whether the cause of these ascending testes was persistence of the processus vaginalis. MATERIALS AND METHODS: A total of 25 boys 4 to 13 years old with no history of testicular maldescent at birth underwent transscrotal orchiopexy in a 2-year period. A total of 33 orchiopexies was performed (8 bilateral). The spermatic cord was carefully dissected and operative findings of the nature of the spermatic cord were noted. RESULTS: In all cases dissection within the spermatic cord revealed a similar finding, namely a fibrous string situated deep to the cremasteric muscle and spermatic fasciae. Transection of this string allowed adequate elongation of the vas deferens and gonadal vessels to permit scrotal placement of the testis. Histological examination revealed characteristic processus vaginalis tissue in which the peritoneal derived mesothelial lining cells were present within a partially obliterated processus vaginalis. CONCLUSIONS: Cryptorchidism presenting later in childhood may be an acquired abnormality caused by failure of natural growth of the spermatic cord when the processus vaginalis leaves a fibrous remnant, which prevents normal elongation. These observations suggest that the ascending testis is acquired postnatally and the cause may be related to inguinal hernia.

Adolescent↗
PubMed1997

Is the ascending testis actually 'stationary'? Normal elongation of the spermatic cord is prevented by a fibrous remnant of the processus vaginalis.

The processus vaginalis (PV) forms as a peritoneal diverticulum within the gubernaculum testis to allow the testis to exit from the abdominal cavity. Failure of its closure leads to inguinal hernias and hydroceles. Ascending testis, which is likely to be an acquired form of undescended testis, may also be part of the spectrum of failure of regression of the PV. At orchidopexy for cryptorchidism in older boys with a history of a scrotal testis in infancy, we find that the PV persists as a fibrous string, preventing normal elongation of the vas deferens and gonadal vessels with increasing size of the boy. We propose that the ascending testis is actually 'stationary', and is caused by persistence of a fibrous remnant of the PV. Seen in this light, ascending testes are directly related to inguinal hernias.

Calcitonin Gene-Related Peptide↗
PubMed1997

Serum levels of müllerian inhibiting substance in preterm and term male neonates.

PURPOSE: Müllerian inhibiting substance, also called anti-müllerian hormone, is responsible in the embryo for the regression of the müllerian structures. During the second and third trimesters the physiological functions that müllerian inhibiting substance may have after the period of müllerian duct regression are poorly understood. We obtained information on müllerian inhibiting substance levels in the male newborn during this period of gestation. MATERIALS AND METHODS: Müllerian inhibiting substance was measured by an enzyme immunoassay in cord blood obtained at birth in 27 preterm (25 to 36 weeks of gestation) and 92 term (37 to 42 weeks) male neonates. RESULTS: Cord serum müllerian inhibiting substance concentrations were relatively high from 25 to 31 weeks (mean plus or minus standard deviation 86.4 +/- 36.1 ng./ml.) and then they decreased from 32 weeks to term (mean 24.2 +/- 14.0 ng./ml.). CONCLUSIONS: The decline early in the third trimester may be consistent with müllerian inhibiting substance having a function during the second but a diminished role in the third trimester.

Anti-Mullerian Hormone↗
PubMed1996

When is hypospadias not hypospadias?

Hypospadias is a deformity of urethral and penile development in the male. Some cases are secondary to more serious disorders of sexual differentiation. Simple clinical rules can sort the common morphological defect of hypospadias from the rarer but more dangerous diagnosis of intersex.

Disorders of Sex Development↗
PubMed1996

The impact of routine obstetric ultrasonographic screening in a low-risk population.

OBJECTIVES: Our goal was to develop a framework for evaluating the current controversy regarding routine obstetric ultrasonography in a population of low-risk pregnancies. STUDY DESIGN: A retrospective chart review was performed for all low-risk pregnancies from a single obstetric practice during 1990 to 1994, to determine the accuracy of screening ultrasonography for fetal anomalies. All patients received a routine ultrasonographic examination at 18 to 20 weeks' gestation. Neonatal records for all patients were evaluated for the presence of both major and minor anomalies. The data were analyzed with attention to the classification of anomalies (all anomalies vs major anomalies, detectable vs nondetectable). RESULTS: A total of 860 fetuses in 854 pregnancies were evaluated. Anomalies were present in 5.35% (46/860); these were major anomalies in 1.16% (10/860) and minor anomalies in 4.19% (36/860). The sensitivity, specificity, and positive and negative predictive values for the diagnosis of all anomalies were 8.7%, 99.9%, 80%, and 95.7%, respectively. However, if only major anomalies detectable by ultrasonography are included, these values become 75%, 100%, 100%, and 99.9%, respectively. There was one false-positive diagnosis not affecting outcome, a small ventriculoseptal cardiac defect. Postnatal ascertainment of anomalies was excellent, as determined by an incidence of ventriculoseptal defects of 1 in 120. CONCLUSION: Distinguishing between major and minor anomalies and between ultrasonographically detectable versus nondetectable anomalies is essential in the evaluation of the diagnostic accuracy of screening ultrasonography. Any comparisons of studies examining the effectiveness of prenatal screening for congenital anomalies with ultrasonography should use the same outcome: major anomalies identifiable by ultrasonography.

Congenital Abnormalities↗
PubMed1996

Selective reduction of multifetal pregnancies to twins improves outcome over nonreduced triplet gestations.

OBJECTIVE: Our purpose was to evaluate effects of multifetal pregnancy reduction on pregnancy complications and birth weights of remaining twin fetuses compared with expectantly managed triplets and nonreduced twins. STUDY DESIGN: Medical records of 54 triplet pregnancies, 59 twin pregnancies resulting from multifetal pregnancy reduction, and 88 sets of twins conceived with assisted reproductive techniques and delivered at New York Hospital after 24 weeks were retrospectively reviewed. Birth weights were corrected for gestational age at delivery by use of a formula derived from composite standardized growth curves. Statistical analysis was performed with chi(2) analysis and Student t test. RESULTS: Twins remaining after reduction and nonreduced twins were less likely to have preeclampsia than were triplets (14% and 23% vs 30%) and to be delivered before 36 weeks (39% and 27% vs 72%). They had birth weights that were > 100 gm larger than those of triplets even when corrected for gestational age. Reduced twins were similar to nonreduced twins in all parameters studied. CONCLUSIONS: Multifetal pregnancy reduction results in pregnancy complications, gestational age, and birth weights closer to those of nonreduced twins than to expectantly managed triplets.

Adult↗
PubMed1996

Multiple gestations from in vitro fertilization: successful implantation alone is not associated with subsequent preeclampsia.

OBJECTIVE: Our purpose was to compare the risk for preeclampsia and severe preeclampsia in triplet and twin gestations and to evaluate the effect of successful implantation on the development of preeclampsia and on perinatal outcome in triplet pregnancies conceived by means of in vitro fertilization. STUDY DESIGN: A case control study was conducted of triplet pregnancies (n = 38) matched for maternal age, parity, race, and delivery date with twin pregnancies (n = 38) resulting from a single fetal reduction (spontaneously or by means of multifetal pregnancy reduction) after successful implantation of triplets. All pregnancies were conceived by means of in vitro fertilization. Rates of preeclampsia and other maternal complications, factors affecting implantation, and perinatal outcomes were compared. Preeclampsia and severe preeclampsia were defined by The American College of Obstetricians and Gynecologists criteria. The Student t test and the chi(2) test were used for statistical analysis. RESULTS: The triplet group had a higher rate of severe preeclampsia (26.3%) than the twin (reduced triplet) group (7.9%). The prevalence of preeclampsia (mild and severe combined) also was higher among the triplet group (44.7%) than among the twin group (15.8%). There was no difference in other maternal complications of pregnancy or in factors potentially affecting implantation, such as assisted hatching. Mean fetal weight was lower among the triplet group, but gestational age at delivery was not significantly different. CONCLUSIONS: The rate of preeclampsia is higher among triplets conceived by means of in vitro fertilization than among triplets conceived by means of in vitro fertilization and reduced to twins. This finding suggests that fetal number, placental mass, or factors unrelated to the success of implantation are more important to the development of preeclampsia than is successful implantation alone.

Adult↗
PubMed1996

Intractable constipation with a decrease in substance P-immunoreactive fibres: is it a variant of intestinal neuronal dysplasia?

After Hirschsprung's disease was ruled out for 25 children who had severe chronic constipation, the authors studied the distribution of immunoreactivity for substance P (SP) and vasoactive intestinal peptide (VIP) in the intestinal wall, using immunofluorescence. SP and VIP immunoreactivity identify excitatory and inhibitory nerve fibres, respectively. Full-thickness rectal biopsy specimens were unsatisfactory, so seromuscular biopsies of the caecum, transverse colon, and sigmoid colon were obtained (by laparoscopy and laparotomy; n = 10 patients). SP-immunoreactive fibres were markedly reduced in seven, with concomitant reduction of VIP-immunoreactive fibres in four. In two other patients, there was no obvious reduction in SP- or VIP-immunoreactive fibres. In a patient who subsequently was found to have multiple endocrine neoplasia type 2b, the myenteric plexus was markedly hyperplastic, with an increase in nerve cells and nerve fibres. VIP-immunoreactive fibres were increased, but SP-immunoreactive fibres were markedly decreased. Surgical options included proximal stoma, Malone operation, and subtotal colectomy with preservation of the rectum. Three children with subtotal colectomy have had improvement over short-term follow-up. The combination of seromuscular laparoscopic biopsies and immunofluorescence demonstration of neuropeptides may identify new variants of intestinal neuronal dysplasia than can be treated successfully with surgery.

Adenomatous Polyposis Coli↗
PubMed1996

Histomorphometric study on germ cell differentiation of unilateral cryptorchidism in the immature pig.

Early spermatogenesis from gonocytes to A-type spermatogonia is inhibited in boys with cryptorchidism. Histological lesions in the undescended testes (UDT) are presumably secondary to the extrascrotal position. The purpose of this study is to determine the abnormalities in number and maturation of germ cells in pigs with undescended testes and to examine the effect of UDT location on early germ cell differentiation. Testicular biopsies from 4-week-old pigs with natural unilateral cryptorchidism (n = 20) were divided into three groups: (1) intraabdominal testes, (2) superficial inguinal pouch testes, and (3) contralateral descended testes (CDT). The testis weight (P < .01) and the area of circular cross-section of the seminiferous tubules (P < .05) in intraabdominal testes was lower than in CDT. The number of germ cells (per tubular cross-section) (P < .05) and A-type spermatogonia (P < .05) in intraabdominal and inguinal testes was significantly lower than in CDT. In contrast, the number of gonocytes in intraabdominal testes was similar to that in CDT. The number of Sertoli cells was similar in the three groups. These results demonstrate that defective transformation of gonocytes to A-type spermatogonia in pigs is similar to that observed in boys with unilateral cryptorchidism. The different locations of UDT in the pig are correlated with the degree of impaired spermatogenesis.

Animals↗