Biomedical subjects

L R Williamson

Publications and source records attributed to L R Williamson.

8 recordsLinked to original sources

PubMed1999

Stag exposure advances the LH surge and behavioral estrus in Eld's deer hinds after CIDR device synchronization of estrus.

The impact of male presence or absence on the timing of the preovulatory LH surge and estrus was studied in 3 experimental groups (n = 6/group) of Eld's deer hinds pretreated with intravaginal progesterone-releasing devices (CIDR-type G) as follows: Group 1 = indirect male contact barn; Group 2 = direct male contact barn; and Group 3 = male isolation barn. For all hinds, the duration of the preovulatory LH surge averaged 2.5+/-0.5 h, whereas mean peak preovulatory and basal LH concentrations were 2.9+/-0.2 ng mL(-1) and 0.27+/-0.03 ng mL(-1), respectively. Nine of 12 male-exposed hinds exhibited a preovulatory LH surge within 24 to 32 h postCIDR device withdrawal, whereas 0 of 6 male-isolated hinds exhibited a preovulatory LH surge during the same time period. Onset of behavioral estrus (45.2+/-2.3, 52.7+/-5.7 and 66.3+/-1.8 h, respectively) was significantly advanced (P<0.05) after CIDR device withdrawal in male exposed hinds (Groups 1 and 2) compared with male isolated hinds (Group 3). These data suggest that stag exposure is important for modulating the timing of the preovulatory LH surge and behavioral estrus after synchronization of estrus with exogenous progestagens.

Administration, Intravaginal↗

PubMed1996

Bilateral osteochondritis dissecans of the elbow in a female pitcher.

We report a case of a 17-year-old female pitcher with bilateral elbow osteochondritis dissecans. Osteochondritis of the elbow is a well-known disorder affecting pitchers and other individuals who sustain repetitive microtrauma to the elbow. Elbow osteochondritis has been described infrequently in female athletes. The incidence and reporting patterns of this disease are likely to increase as more female athletes participate in organized sports.

Adolescent↗

PubMed1995

Urinary 3 alpha,17 beta-androstanediol glucuronide is a measure of androgenic status in Eld's deer stags (Cervus eldi thamin).

To determine the primary excretory by-products of testosterone (T), 85 microCi [3H]T was administered i.v. to two adult Eld's deer stags. Blood (10 ml) was collected by jugular venipuncture at 0, 5, 10, 15, 30, 45, 60, 90, 120, 150, 180, 240, and 480 min after isotope infusion, and all urine and feces were collected for 96 h after injection. Seventy percent of labeled circulating steroid was conjugated by 30 min postinfusion. The majority (80.4 +/- 3.2%) of T metabolites were excreted into urine, and 95.0 +/- 0.9% of these were conjugated, 95.8 +/- 0.2% being hydrolyzable with glucuronidase. Seven urinary androgen metabolites, including androstanediol (5 alpha-androstan-3 alpha-17 beta-diol and 5 beta-androstan-3 alpha-17 beta-diol), were identified in glucoronidase-hydrolyzed, ether-extracted Eld's deer urine pools after gas chromatography/mass spectrometry. A double-antibody 125I RIA for 5 alpha-androstanediol-3 alpha, 17 beta-diol,17-glucuronide (3 alpha-diol-G) was validated for unprocessed urine. Longitudinal assessments of urine samples collected from 13 stages for 3 yr revealed biological concordance between fluctuations in urinary 3 alpha-diol-G and serum T, as well as seasonal changes in secondary sexual characteristics. Overall correlation between "same-day" matched serum T and urinary 3 alpha-diol-G was 0.58, (n = 6; p < 0.001). Thus, monitoring urinary 3 alpha-diol-G provides a noninvasive, alternative method for characterizing male endocrine interrelationships in an endangered ungulate species.

Androgens↗

PubMed1993

Circannual inter-relationships among reproductive hormones, gross morphometry, behaviour, ejaculate characteristics and testicular histology in Eld's deer stags (Cervus eldi thamin).

Blood samples, morphometric measurements and behavioural data were collected weekly for 52 weeks from six adult Eld's deer stags exposed to natural fluctuations in photoperiod (38 degrees N latitude). Mean (+/- SEM) serum LH concentrations reached peak values in the autumn (October), three months before FSH and testosterone concentrations reached peak values in early winter (January). Prolactin concentrations were inversely related (r = -0.733, P < 0.001) to LH and directly related to daylength, and maximal concentrations were observed during mid-summer (July) and minimal concentrations during early winter (January). The temporal pattern of circulating inhibin was positively correlated with FSH (r = 0.88, P < 0.001), but lagged behind the seasonal FSH increase by 1-3 weeks. Antler length, body weight and chest girth were maximal during pre-rut (December-January). Maximal scrotal circumference and combined testes volume were observed in mid-winter (February), whereas peak neck girth and behavioural aggression occurred 1-3 months later (March-May). On the basis of quarterly electroejaculation results, motile spermatozoa were produced in all seasons. However, the greatest number of motile spermatozoa per ejaculate was observed during the winter and spring, whereas the highest incidence of sperm pleiomorphisms (> 80%) was detected in the autumn. Histological assessments of the regressed testis (July) revealed fewer germ cells undergoing spermatogenesis and an increased incidence of degenerating and abnormal cell types. In summary, Eld's deer exhibit a circannual hypothalamic-pituitary-gonadal cycle with onset of pituitary activation occurring during the autumn and winter, whereas gonadal activity peaks during the winter and spring as daylengths are increasing. Marked circannual variations in circulating prolactin suggest that Eld's deer may use photoperiodic cues to modulate seasonal fertility; however, the existence of an endogenous seasonal rhythm operating independently of photoperiod cannot be excluded.

Animals↗

PubMed1993

Seasonal patterns of basal and GnRH-induced LH, FSH and testosterone secretion in Eld's deer stags (Cervus eldi thamin).

Plasma LH, FSH and testosterone were measured in blood samples collected via remote catheterization from six adult Eld's deer stags every 10 min for 8 h before and 2 h after GnRH (1 microgram kg-1, i.v.) administration. Blood samples were collected within 2 weeks of the summer solstice (21 June), autumn equinox (22 September), winter solstice (21 December) and spring equinox (20 March). Marked seasonal variations in basal LH, FSH and testosterone concentrations were observed. From autumn, well-defined LH pulses were temporally associated with small, but detectable pulses in testosterone. During the winter transition into the breeding season, episodic LH pulses were also temporally associated with corresponding testosterone surges that lasted 2-3 h. High amplitude, low frequency testosterone surges were also observed during the spring, but often in the absence of detectable LH pulses. Basal LH and testosterone concentrations decreased during the summer and, although LH pulses were detected, associated testosterone pulses were absent. Only 37% of LH pulses occurred coincidentally with FSH pulses, and FSH pulses were generally less prominent. The increases in LH and FSH above basal concentrations after GnRH treatment were significant (P < 0.05) for all seasons. Increases in testosterone after GnRH treatment were greatest during the winter and spring, but testosterone also increased to a lesser extent during the autumn (P < 0.05). In contrast, testosterone concentrations were not different before and after GnRH treatment during summer.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

Successful intrauterine insemination of Eld's deer (Cervus eldi thamin) with frozen-thawed spermatozoa.

This study tested the efficacy of assisted reproduction (synchronization of oestrus and intrauterine artificial insemination (AI)) in contributing to the captive propagation of an endangered species, the Eld's deer (Cervus eldi thamin). Semen was collected from males preselected on the basis of under-represented genotype. Motility of spermatozoa after thawing from ejaculates diluted with BF5F extender (8% glycerol), frozen on dry ice in 0.5 ml straws and stored in liquid nitrogen was 60-70%. Intravaginal progesterone-releasing devices (controlled internal drug release, CIDR-type G) were inserted into 20 adult Eld's deer hinds for 14 days. In all hinds, semen (7.5-10 x 10(6) motile spermatozoa per uterine horn) was deposited by laparoscopy performed 70 h after removal of the CIDR device. Ovarian activity, before and after AI, was monitored by analysing pregnanediol-3 alpha-glucuronide (PdG) concentrations in voided urine collected three to seven times per week. During the period of CIDR device insertion, urinary PdG profiles were equal to, or above, normal luteal phase concentrations in all hinds. Within 48 h of device withdrawal, PdG concentrations returned to baseline values in 17 of the 20 females, and the onset of behavioural oestrus occurred at this time in 12 hinds. On the basis of sustained increases in urinary PdG, 9 of the 20 hinds were diagnosed as pregnant by 90 days after AI, all of which delivered offspring after a mean gestation of 241.1 days (range, 235-245). Seven singletons (two females, five males) were born alive and survived, and one singleton and one set of twins were stillborn (three females).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1989

Nucleotide sequence of the Rickettsia prowazekii ATP/ADP translocase-encoding gene.

The Rickettsia prowazekii ATP/ADP translocase (Tlc) gene (tlc), previously cloned in Escherichia coli was localized to a 1.6-kb chromosomal fragment. Nucleotide sequence analysis of this fragment revealed an open reading frame of 1494 bp that could encode a hydrophobic protein of 497 amino acids (aa) with an Mr of 56,668. Analysis of the deduced aa sequence revealed that it contained twelve potential membrane-spanning regions. Comparisons between the deduced aa sequence of the R. prowazekii ATP/ADP Tlc and the sequences of mitochondrial (mt) Tlc revealed no detectable homologies between the rickettsial and mt sequences. The major protein synthesized in E. coli minicells containing the rickettsial gene exhibited and Mr of approx. 34,000.

Amino Acid Sequence↗

PubMed1987

Nucleotide sequence of the Rickettsia prowazekii citrate synthase gene.

The Rickettsia prowazekii citrate synthase (gltA) gene, previously cloned in Escherichia coli, was localized to a 2.0-kilobase chromosomal fragment. DNA sequence analysis of a portion of this fragment revealed an open reading frame of 1,308 base pairs that encodes a protein of 435 amino acids with a molecular weight of 49,171. This translation product is comparable in size to both the E. coli and pig heart citrate synthase monomers and to the protein synthesized in E. coli minicells containing the rickettsial gene. Comparisons between the deduced amino acid sequence of R. prowazekii citrate synthase and those of the E. coli and pig heart enzymes revealed extensive homology (59%) between the two bacterial proteins. In contrast, only 20% of the rickettsial enzyme residues were shared with the functionally similar pig heart enzyme residues. Upstream from the open reading frame and in close proximity to one another, sequences with homology to E. coli consensus sequences for RNA polymerase and ribosome binding were identified. S1 nuclease mapping experiments demonstrated that the start of transcription for this gene in E. coli was located in the upstream region. Codon usage in the rickettsial gltA gene was found to be very biased and differed from the pattern observed in E. coli. Adenine and uracil were used preferentially in the third base position of rickettsial codons.

Amino Acid Sequence↗