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Biomedical subjects

B L Becker

Publications and source records attributed to B L Becker.

15 recordsLinked to original sources
PubMed1998

Use of a GnRH agonist to suppress testosterone in wild male Hawaiian monk seals (Monachus schauinslandi).

A gonadotropin-releasing hormone (GnRH) agonist, d-Trp6-LHRH, was evaluated for its effectiveness in reducing circulating testosterone concentrations in wild Hawaiian monk seals (Monachus schauinslandi). Twenty-eight adult male seals were randomly divided into three groups: 10 were captured and treated with 7.5 mg of the GnRH agonist, 9 were captured but did not receive the agonist, and 9 were captured near the end of the study to serve as handling controls. Blood samples were taken from all 28 seals. From 14 to 58 days after initial capture, 8 of the treated seals and 8 of the untreated seals were recaptured and a second sample of blood was taken. For comparison, blood was also collected from 4 captive adult male seals during the same months as the field study. In the treated group, the agonist induced a significant decline in mean circulating testosterone concentrations, from 1.01 ng/ml (first sample) to 0.21 ng/ml (second sample, taken approximately 38 days later). In the untreated group, mean testosterone concentrations of the first and second samples were statistically indistinguishable (1.11 vs 1.16 ng/ml). The mean concentration of the untreated group (second sample) was also indistinguishable from the mean concentration of seals in the control group (1.16 vs 0.82 ng/ml). Also, mean testosterone concentration in the initial samples from the four captive seals was not statistically different from that of untreated wild seals (1.38 vs 1.11 ng/ml). These results suggest that (1) the GnRH agonist suppresses the production of testosterone in wild adult male Hawaiian monk seals, (2) a single handling of adult male seals does not affect their testosterone levels, and (3) testosterone concentrations in captive male seals appear to be consistent with concentrations in wild seals. Further evaluation of this GnRH agonist is necessary before it is used in the management of this endangered species, but these results suggest it may be a useful tool for reducing mortality of monk seals from adult male aggression related to reproduction and mating behavior.

Animals↗
PubMed1998

Postoperative management of the patellofemoral patient.

Postoperative management of the patellofemoral patient requires the clinician to implement a program which reestablishes functional activities of daily living. This paper will discuss the postoperative management of the patellofemoral patient. Effective rehabilitation techniques are needed to progress the patient. Surgical procedures, such as a lateral retinacular release, proximal realignment, and distal realignments, are frequently utilized techniques; however, long-term clinical outcome studies are lacking. The postoperative protocols discussed utilize an evaluation-based treatment approach model. The model defines evaluation techniques, leading the clinician to a specific rehabilitation pathway. The crucial element of postoperative management focuses on a treatment and exercise approach similar to the nonoperative management. Inappropriate or overly aggressive exercises may lead to possible neurologic dysfunction or delayed muscle function. The clinician must recognize that patients may exhibit articular cartilage damage, and, thus, rehabilitation programs must be designed to minimize the potential risks of progressing this lesion.

Exercise Therapy↗
PubMed1994

Reproductive morphology and status of female Hawaiian monk seals (Monachus schauinslandi) fatally injured by adult male seals.

Female Hawaiian monk seals at Laysan Island in the Northwestern Hawaiian Islands seasonally risk aggressive mating attempts by groups of adult male monk seals. These attacks, which also target immature female and male seals at a lower frequency, result in injuries that are often fatal and are termed mobbings. This study was undertaken to assess the reproductive status of nine female seals that died after mobbing attacks and to obtain basic morphological data of reproductive tracts from ten females. Reproductive morphology of the seals indicated that the lengths of the uterine body and both uterine horns were significantly shorter in nulliparous than in parous seals. Seven of the nine seals were periovulatory, on the basis of gross morphology of the ovaries at death. The ovaries of the other two seals possessed immature follicles. Histological studies of the vagina and uterus confirmed the reproductive status of the seals. When the reproductive status at the time of first injury was estimated, all seals were in the follicular phase of the oestrous cycle. At least four of these seals were estimated to be in oestrus at the time of their first injury, and seven of the seals sustained at least one injury during the estimated period of oestrus (2-6 days). These results support the hypothesis that most adult female Hawaiian monk seals that die following an attack by male monk seals are periovulatory, and that the majority of the attacks occur during oestrus.

Animals↗