PubMed Health⌕ Search

Biomedical subjects

K G Gould

Publications and source records attributed to K G Gould.

At least 19 recordsLinked to original sources
PubMed1995

LMP2+ proteasomes are required for the presentation of specific antigens to cytotoxic T lymphocytes.

BACKGROUND: Major histocompatibility complex (MHC) class I molecules present short peptides generated by intracellular protein degradation to cytotoxic T lymphocytes (CTL). The multisubunit, non-lysosomal proteinases known as proteasomes have been implicated in the generation of these peptides. Two interferon-gamma (IFN-gamma)-inducible proteasome subunits, LMP2 and LMP7, are encoded within the MHC gene cluster in a region associated with antigen presentation. The incorporation of these LMP subunits into proteasomes may alter their activity so as to favour the generation of peptides able to bind to MHC class I molecules. It has been difficult, however, to demonstrate a specific requirement for LMP2 or LMP7 in the presentation of peptide epitopes to CTL. RESULTS: We describe a T-cell lymphoma, termed SP3, that displays a novel selective defect in MHC class I-restricted presentation of influenza virus antigens. Of the MHC-encoded genes implicated in the class I pathway, only LMP2 is underexpressed in SP3 cells. Expression of IFN-gamma in transfected SP3 cells simultaneously restores LMP2 expression and antigen presentation to CTL. Expression of antisense-LMP2 mRNA in these IFN-gamma-transfected cells selectively represses antigen recognition and the induction of surface class I MHC expression. Moreover, the expression of this antisense-LMP2 mRNA in L929 fibroblast cells, which constitutively express LMP2 and have no presentation defect, blocks the presentation of the same influenza virus antigens that SP3 cells are defective in presenting. CONCLUSIONS: Our results show that the LMP2 proteasome subunit can directly influence both MHC class I-restricted antigen presentation and class I surface expression.

Animals↗
PubMed1995

Solid phase synthesis of 5'-diphosphorylated oligoribonucleotides and their conversion to capped m7Gppp-oligoribonucleotides for use as primers for influenza A virus RNA polymerase in vitro.

We have synthesized four different 5'-diphosphorylated oligoribonucleotides, varying in length from 11 to 13 nucleotides by a new solid phase method. After deprotection and partial purification the 5'-diphosphorylated oligoribonucleotides could be converted to capped (m7Gppp) oligoribonucleotides using guanylyl transferase. Radiolabelled capped oligoribonucleotides acted as primers for the influenza A virus RNA polymerase in vitro. The solid phase method described here should also allow the addition of 5'-diphosphates to synthetic oligodeoxyribonucleotides and be capable automation.

Base Sequence↗
PubMed1995

Effect of diet on lignans and isoflavonoid phytoestrogens in chimpanzees.

Diphenolic compounds belonging to the classes of lignans and isoflavonoids have been identified in urine of man and animals, including the chimpanzee. Some of these compounds, formed by intestinal bacteria from plant lignans and phytoestrogens, have been shown in animal studies to exhibit biological activities that suggest they could function as cancer-protective compounds. The effect of diet on urinary excretion of these compounds in the adult male chimpanzee has been studied. It was found that the chimpanzees consuming their regular food excreted large amounts of the isoflavonoid phytoestrogens, equol (mean +/- SE) (127.5 +/- 34.0 nmol/mg cr.) and daidzein (20.7 +/- 9.0 nmol/mg cr.) and the lignan, enterolactone (14.1 + 3.5 nmol/mg cr.). Small amounts of the lignan, enterodiol, (0.4 +/- 0.2 nmol/mg cr.) were also excreted. On all other four test diets (high protein, high carbohydrate, high vegetable, and high fat), the excretion was less, particularly on a high fat diet where the excretion of all diphenolic compounds was reduced by more than 90% to a level observed in omnivorous human subjects or women with breast cancer. These results suggest that diet profoundly influences the excretion of both animal lignans and phytoestrogens in urine. Because non-human primates are particularly resistant to mammary and genital carcinoma on estrogen treatment, the present data suggest that the very high levels of phytoestrogens and lignans as found during exposure to the regular diet may partially account for why these primates are so resistant to hormonal manipulations to induce cancer.

Animals↗
PubMed1995

Metabolism of 1 alpha-hydroxyvitamin D2 to activated dihydroxyvitamin D 2 metabolites decreases endogenous 1 alpha, 25-dihydroxyvitamin D 3 in rats and monkeys.

The vitamin D analog 1 alpha-hydroxyvitamin D2 (1 alpha-OHD2) is under development for the treatment of secondary hyperparathyroidism and metabolic bone disease. This analog is metabolized in vivo to the natural active dihydroxylated metabolite of vitamin D2, 1 alpha,25-dihydroxyvitamin D2 [1 alpha,25-(OH)2D2]. To study the metabolism of this analog, an assay involving HPLC separation and purification of metabolites followed by RRA with the vitamin D receptor was developed to quantitate the active metabolites of the analog and the endogenous active metabolite of vitamin D3, 1 alpha,25-(OH)2D3, from the same blood sample. This assay was used to determine blood levels of active dihydroxylated vitamin D compounds in rats and monkeys treated with oral 1 alpha-OHD2. As the circulating 1 alpha,25-(OH)2D2 level increased dose dependently in these rats and monkeys, a concomitant decrease in the endogenous 1 alpha,25-(OH)2D3 was observed. In rats orally administered more than 2.5 micrograms 1 alpha-OHD2/kg.day, a second active metabolite of 1 alpha-OHD2, 1 alpha,24-(OH)2D2, was detected in concentrations similar to those of 1 alpha,25-(OH)2D2. These results indicate that the regulatory control of endogenous vitamin D metabolism as well as analog metabolism must be considered when assessing the therapeutic potential of a vitamin D analog.

Animals↗
PubMed1994

Sexual behavior of chimpanzees (Pan troglodytes): male versus female regulation.

We investigated the sexual behavior of 13 chimpanzees (Pan troglodytes) in 2 types of pair test in order to clarify the interaction of social variables with female hormonal state. The frequency of copulation in tests in which the partners were freely accessible to each other was related to the male's dominance over the female; copulation was less frequent and was related to social compatibility in tests in which the female controlled access. Copulation was related to female hormonal state in both types of test. The results demonstrate (a) an association between female hormonal state and sexual activity of chimpanzees, (b) the influence of social relationships on sexual interactions, and (c) the importance of focusing on female sexual behavior before copulation, rather than copulation per se, in research on sexual arousability of female primates.

Animals↗
PubMed1994

Neonatal treatment with luteinizing hormone-releasing hormone analogs alters peripheral lymphocyte subsets and cellular and humorally mediated immune responses in juvenile and adult male monkeys.

We examined the effect of treatment with a LH-releasing hormone (LHRH) agonist (Ag), antagonist (Ant), or Ant and androgen (Ant/And) for the first 4 months of postnatal life on lymphocyte subsets and cellular and humorally mediated immune responses in juvenile and adult male monkeys. We also determined the effect of 9 weeks of Ant treatment on lymphocyte subsets in adult male monkeys. Adult male monkeys that had been treated neonatally with an Ag had increased levels of CD8-positive (CD8+) T-cells and reduced levels of B-cells compared to vehicle-treated controls. Lymphocytes from these animals also showed an elevated proliferative response to a variety of mitogens compared to cells from control animals. Antibody production in response to tetanus toxoid was normal in treated animals. Other neonates treated with Ant/And exhibited subnormal levels of lymphocytes, CD8+ T-cells, and B-cells at 4 months of age. Similar changes, but of lesser magnitude, were observed in animals treated with Ant alone. At 6 months of age, lymphocytes from both groups of Ant-treated monkeys exhibited an above normal proliferative response to streptolysin-O, but not to other mitogens. At 18 months of age, animals treated with Ant alone produced more antitetanus antibody in response to a tetanus toxoid booster than the controls or Ant/And-treated animals. Ant treatment was without major effect on lymphocyte subsets in adult monkeys. Serum LH and testosterone levels declined, and there was a small but significant increase in B-cells, lymphocytes expressing the interleukin-2 receptor, and the CD4+/CD8+ T-cell ratio during treatment, but these parameters normalized during the posttreatment period. The data suggest that chronic neonatal treatment with an Ag or Ant alters the development of immune system responses in male primates. The significance of these changes and their impact on the ability of these animals to respond to pathogenic agents is under investigation.

Aging↗
PubMed1993

Precise prediction of a Kk-restricted cytotoxic T cell epitope in the NS1 protein of influenza virus using an MHC allele-specific motif.

The nonstructural protein NS1 of influenza A/PR/8/34 virus has previously been reported to be recognized by murine Kk-restricted cytotoxic T lymphocytes (CTL), although the sequence of the epitope was not defined. A Kk-specific motif has previously been published and consists of a glutamic acid or (less frequently) an aspartic acid at position 2 and an isoleucine at the carboxyl terminus of a peptide eight or nine residues long. This motif was used here to predict the sequence of the NS1 epitope, which was defined as a nonapeptide corresponding to amino acid residues 152-160, sequence EEGAIVGEI. This is the first CTL epitope to be defined within the NS1 protein of the influenza A virus. A model of how this epitope could bind to the Kk molecule was produced by homology modelling from an X-ray crystal structure of a human HLA/peptide complex.

Alleles↗
PubMed1993

Effects of an oral contraceptive on sexual behavior of chimpanzees (Pan troglodytes)

Behavioral and physiological effects of a combined oral contraceptive (OC) were studied in chimpanzees for comparative purposes related to (i) the ambiguity surrounding the effects of OCs on the sexuality of humans, (ii) the close biological relationship between chimpanzees and humans, especially with respect to endogenous sex hormones and sexual behavior, and (iii) the relatively greater behavioral sensitivity of the chimpanzee to changes in sex hormone levels such as those that accompany the use of OCs. Two different types of pair tests and detailed behavioral assessments were used to differentiate the hormonal effects of female behavior from social effects imposed by the male. Anogenital swelling and copulation were reduced during OC cycles, but the effect of the OC on copulation was directly related to the social and sexual relationship of the pair during natural cycles. The more compatible and more frequently copulating pairs in the natural cycles continued to copulate during the OC cycles, albeit at reduced rates, whereas the less compatible and less frequently copulating pairs ceased copulating altogether when the female received the OC. There was no independent effect of the OC on ejaculation per se. Both male and female sexual initiative were reduced in the OC cycles, but female responsiveness to male sexual solicitations and direct copulatory attempts were not affected. Data indicate that despite generally adverse effects of the OC on certain physiological and behavioral dimensions of sexuality, social factors ultimately determined the degree of response to the OC.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Preservation of bone mass in hypogonadal female monkeys with recombinant human growth hormone administration.

This study examined the effect of human recombinant GH supplementation on bone loss in female monkeys made hypogonadal with GnRH agonist (GnRH-Ag). Animals were randomly assigned to three treatment groups: vehicle, GnRH-Ag, and GnRH-Ag and GH. After an initial 5-month pretreatment period during which all animals were maintained on a normal monkey chow diet containing a high level of calcium (1%) animals were maintained on a normal monkey chow diet containing a high level of calcium (1%), animals were shifted to a lower calcium diet (0.1%) for 4 to 5 months before the beginning of treatment and were maintained on this diet throughout the remainder of the study. Monkeys were treated continuously for 10 months with 25 micrograms/day GnRH-Ag or vehicle. GH was administered by im injection three times per week at a dose of 100 micrograms/kg body wt/day. Animals treated with GnRH-Ag were amenorrheic throughout the treatment period, and serum estradiol and progesterone levels were below minimum levels of detection. Vehicle-treated animals continued to cycle throughout the study. Monkeys treated with GnRH-Ag alone showed a significant decline (12%) in bone mineral density (BMD) of the lumbar spine. BMD was reduced below pretreatment levels from 6 months of GnRH-Ag treatment through 3 months post treatment in this group. GH supplementation reduced the decline of BMD in GnRH-Ag-treated monkeys. BMD did not change significantly with time in the GH-supplemented group. BMD values in GH supplemented animals between 5 and 10 months of the treatment period exceeded levels in animals treated with GnRH-Ag alone, but BMD levels during this interval were lower than in the vehicle-treated group. In the vehicle-treated group, there was small, but significant, increase in BMD over the course of the study. Serum osteocalcin concentrations were elevated above pretreatment values after 6 and 9 months of GnRH-Ag treatment alone or with GH supplementation, but did not change in vehicle-treated animals. GH also increased serum insulin-like growth factor 1 levels. In response to the lower calcium diet, serum PTH levels increased approximately 200% in vehicle-treated monkeys and animals treated with GnRH-Ag alone. GH attenuated this increase in serum PTH. The data indicate that the level of calcium in the diet of adult monkeys can be reduced more than 10-fold without affecting lumbar BMD provided ovarian function is normal, but if animals are made hypogonadal with a GnRH-Ag, bone mass declines.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1992

Hormone levels and anogenital swelling of female chimpanzees as a function of estrogen dosage in a combined oral contraceptive.

A combined oral contraceptive consisting of ethinyl estradiol (EE2) in three dosages (50, 100, and 400 micrograms) and norethindrone (0.5 mg) was given to female chimpanzees to determine the effect on endogenous sex hormone levels and anogenital swelling. Serum levels of EE2 increased with increasing dosages of EE2, estradiol decreased, and luteinizing hormone, progesterone and testosterone were maintained at approximately midfollicular phase levels. Urinary levels of EE2 glucuronide increased with the increasing dosages of EE2, whereas estrone and pregnanediol glucuronide were essentially undetectable. The cyclic increase in female anogenital swelling was abolished when the norethindrone was combined with 50 micrograms of EE2 and relatively constant and low levels of swelling were recorded. Relatively constant but successively higher levels of swelling were recorded when the norethindrone was combined with the higher dosages of EE2. These effects of oral contraceptives on female genital tissues are relevant to our laboratory studies of sexual behavior in chimpanzees given oral contraceptives and could also have implications for women taking oral contraceptives.

Anal Canal↗
PubMed1991

Characterization of two distinct major histocompatibility complex class I Kk-restricted T-cell epitopes within the influenza A/PR/8/34 virus hemagglutinin.

Cytotoxic T-lymphocyte (CTL) clones specific for the influenza A/PR/8/34 virus hemagglutinin (HA) were isolated by priming CBA mice with a recombinant vaccinia virus expressing the HA molecule. The epitopes recognized by two of these clones, which were CD8+, Kk restricted, and HA subtype specific, were defined by using a combination of recombinant vaccinia viruses expressing HA fragments and synthetic peptides. One epitope is in the HA1 subunit at residues 259 to 266 (numbering from the initiator methionine), amino acid sequence FEANGNLI, and the other epitope is in the HA2 subunit at residues 10 to 18 (numbering from the amino terminus of the HA2 subunit), sequence IEGGWTGMI. These two peptides are good candidates for naturally processed HA epitopes presented during influenza infection, as they are the same length (eight and nine residues) as other naturally processed viral peptides presented to CTL. A comparison of the sequences of these two new epitopes with those of the three previously published Kk-restricted T-cell epitopes showed some homology among all of the epitopes, suggesting a binding motif. In particular, an isoleucine residue at the carboxy-terminal end is present in all of the epitopes. On the basis of this homology, we predicted that the Kk-restricted epitope in influenza virus nucleoprotein, previously defined as residues 50 to 63, was contained within residues 50 to 57, sequence SDYEGRLI. This shorter peptide was found to sensitize target cells at a 200-fold lower concentration than did nucleoprotein residues 50 to 63 when tested with a CTL clone, confirming the alignment of Kk-restricted epitopes.

Amino Acid Sequence↗
PubMed1991

Effect of clomiphene citrate upon periovulatory endometrial development in the baboon.

Endometrial histology in baboons (Papio cynocephalus anubis) was evaluated after five days of clomiphene citrate (CC) treatment initiated on either cycle day six (n = 8) or ten (n = 4). Biopsies performed before and after a human chorionic gonadotropin (hCG) induced ovulation were compared to non-CC treated controls. Although CC had a definite antiestrogenic effect on perineal skin, no significant effect of endometrial proliferation was demonstrable.

Animals↗
PubMed1990

A potential primate model for bone loss resulting from medical oophorectomy or menopause.

This study examined the potential use of the GnRH agonist-treated female monkey as a model for bone loss after medical oophorectomy or the onset of menopause in women. Three female rhesus monkeys (13-16 yr of age) were treated continuously for 10 months with 25 micrograms/day GnRH agonist using osmotic minipumps. All three animals exhibited normal menstrual cycles before treatment. Within 5 weeks of the beginning of GnRH agonist treatment, serum progesterone and estradiol concentrations had fallen to low values and did not rise significantly during the remaining treatment period. The decline in ovarian steroidogenesis was correlated with a reduction in bone mineral density (BMD; bone mineral content/bone width) of the caudal vertebrae and humerus. The reduction of BMD of the caudal vertebrae occurred gradually. The downward trend was evident during the first 3 treatment months, but did not fall significantly below pretreatment levels until 9 months of GnRN agonist treatment. The overall decline in BMD for the caudal vertebrae was approximately 14% after 9 months of GnRH agonist treatment. The measured decline in BMD of the humorous was 11%. Serum osteocalcin levels rose more than 10-fold above pretreatment values between 4 and 7 months of GnRH agonist treatment before declining to levels that approached pretreatment concentrations between 8 and 10 months of treatment. Menstrual cycles were reinitiated within 4 weeks after the termination of treatment, as shown by luteal phase increases in serum progesterone concentrations. BMD of the humerus and caudal vertebrae remained subnormal 2 months posttreatment, but by 5 months had recovered to near-pretreatment values. These data suggest that ovarian hormone deprivation induced by GnRH agonist administration is associated with a decline in BMD in female monkeys, and that this animal model may be an excellent model for postmenopausal bone loss or bone reduction resulting from medical oophorectomy. The GnRH agonist-treated monkey also has the potential to be developed as a model for type I postmenopausal osteoporosis.

Amino Acid Sequence↗
PubMed1990

Techniques and significance of gamete collection and storage in the great apes.

Rectal probe electroejaculation (RPE) is the most frequently used method for semen recovery in the great apes. Artificial insemination has been successful in the chimpanzee and gorilla. Oocytes can be recovered using laparoscopic techniques similar to those used in human medicine. At this time there has been no successful in vitro fertilization with birth of an infant in the great apes. Semen can be successfully frozen in the apes, as documented by recovery of motility of sperm after thawing. Pregnancies have been initiated in the chimpanzee and gorilla using frozen thawed semen.

Animals↗
PubMed1989

Effects of age and sex on bone density in the rhesus monkey.

Normative data for bone density of cortical and trabecular bone in the rhesus monkeys is described in the present study. Changes of bone density (g/cm2) for the humerus, the third lumbar vertebra, and the eighth caudal vertebra of the rhesus monkey show differences due to age and sex of the subjects (males n = 57; females n = 49). In general, bone density increased with age and then reached a plateau at approximately 3 to 4 years in all bones measured. In the humerus, older females (greater than 30 years) had a significantly lower bone density than females of 4 to 24 years, while bone density in older males did not decrease. In the vertebrae, some evidence of advanced age-related decreases in bone density was found in both sexes. These results indicate that the rhesus monkey shows a natural pattern of change in bone mineralization which parallels that seen in humans. The physiological similarity between the rhesus monkey and human further suggests a potential role for this species in the future investigation of osteoporosis.

Aging↗