Biomedical subjects

B S Minhas

Publications and source records attributed to B S Minhas.

At least 19 recordsLinked to original sources

PubMed1996

Methods for enhancement of sperm function.

From a review of recent advances in human reproduction, it is apparent that therapeutic approaches to male infertility have been revolutionized. While our understanding of sperm function at the molecular level is steadily increasing, the realization of consistent oocyte fertilization by mechanically bypassing natural barriers has given new perspective for future investigation. This chapter reviews current knowledge of adjuvants that enhance sperm function and lend themselves to clinical application. Each compound is presented with recent publications supporting proposed mechanisms of action. Specifically, follicular fluid, progesterone, pentoxifylline, platelet activating factor and other cytokines have been studied for their impact on the in vitro fertilization capacity of spermatozoa. Intracytoplasmic sperm injection (ICSI) has provided infertile couples with hope for successful reproduction without sperm donation. The precise mechanism that allows subsequent pronuclear formation and syngamy is currently unknown and experimental models are few. Adjuvants that can be used in conjunction with controlled ovarian stimulation and intrauterine insemination are prominent areas for further research as this would provide an alternative to the expense and risks of in vitro fertilization and embryo transfer.

Cytokines↗

PubMed1996

Platelet activating factor and conception.

PURPOSE: This review provides evidence for the involvement of platelet activating factor (PAF) in the several facets of pregnancy establishment. METHODS: A comprehensive literature review and new data. RESULTS: PAF has a role in spermatozoal function, fertilization, embryo development, and implantation. CONCLUSIONS: PAF is intimately involved in conception.

Animals↗

PubMed1996

Antibiotic prophylaxis in percutaneous endoscopic gastrostomy.

OBJECTIVES: The benefit of antibiotic prophylaxis in percutaneous endoscopic gastrostomy is controversial. The aim of this study is to determine whether prophylactic antibiotic treatment with Cefazolin reduces the incidence of peristomal infection after percutaneous endoscopic gastrostomy. METHODS: Of the 131 hospitalized or nursing home patients referred for percutaneous endoscopic gastrostomy, 115 were enrolled in a prospective randomized double-blind placebo controlled trial. Sixty-one (group 1) were randomized in a double-blind fashion and received either Cefazolin or saline pregastrostomy. Fifty-four patients (group 2) were on antibiotics for prior medical indications pregastrostomy. Patients had their peristomal area evaluated on a daily basis for 1 wk after gastrostomy. Erythema and exudate were scored on a scale from 0 to 4; induration was scored on a scale of 0 to 3; a maximum score of 8 or higher or the presence of pus was criteria for infection. RESULTS: Wound infection occurred in 4 of 30 (13%) participants receiving Cefazolin and in 6 of 31 (19%) participants receiving saline (p > 0.5). In the 54 patients on antibiotics for prior indications, wound infection was observed in 2 subjects (3%). This finding was a significant difference when compared with the placebo group (p < 0.02). CONCLUSIONS: A single dose of Cefazolin prophylaxis does not reduce the overall peristomal wound infection in percutaneous endoscopic gastrostomy. Patients receiving prior extended antibiotic therapy have fewer peristomal wound infections.

Anti-Bacterial Agents↗

PubMed1994

Expression and role of c-myc protooncogene in murine preimplantation embryonic development.

PURPOSE: The present study was conducted to investigate the expression and possible role of the c-myc protooncogene in preimplantation embryos by using reverse-transcriptase/polymerase chain reaction (RT-PCR) technique and microinjection of synthetic antisense c-myc oligonucleotide probe, respectively. Total RNA was extracted from oocytes and two cell-, four cell-, early morula-, late morula-, early blastocyst-, and late blastocyst-stage embryos, and cDNA was constructed using MMLV reverse transcriptase. Sense primer (P1) and antisense primer (P2) used were based on the c-myc gene sequence bp 1609-1629 and bp 3279-3299, respectively, that span a 1.37-kb intron. PCR-amplified products of cDNA from oocyte-, two cell-, four cell-, early and late morula-, and blastocyst-stage embryos demonstrated the expected 313-bp product in Southern blot hybridization using a c-myc specific DNA probe, with an indication of lower levels in oocytes and early morulae. RESULTS: Cytoplasmic injection of the antisense c-myc oligonucleotide probe (P2) and not the sense probe (P1) into pronuclear-stage zygotes caused a significant (P = 0.02 to 0.0001) inhibition of development to blastocysts in a concentration-dependent manner, with a maximal inhibition at the first cleavage of zygotes to two cell-stage embryos. There was no effect on the P2 antisense injection on pronucleus formation. CONCLUSION: These results indicate that the c-myc protooncogene is expressed in preimplantation embryos and may have an essential role in normal embryogenesis in mice.

Animals↗

PubMed1994

Platelet activating factor treatment of spermatozoa enhances rabbit oocyte fertilization following subzonal sperm insertion.

PURPOSE: The objective of this study was to evaluate the effects of spermatozoal platelet activating factor (PAF) treatment on fertilization rates employing subzonal sperm insertion in the rabbit. STUDY DESIGN: Oocytes (n = 130) with distinct first polar bodies were injected with three to seven motile spermatozoa. Half (n = 65) of the oocytes were injected with PAF-treated sperm, whereas the other half (n = 65) served as controls and were injected with nontreated sperm. Fertilization rates were assessed by the formation of two pronuclei followed by cleavage to the two-cell stage. RESULTS: In the group of oocytes injected with PAF-treated sperm, we noted a significant (P < 0.001) improvement in fertilization rates, 61.5% (40/65), vs. control nontreated sperm, 20.0% (13/65). Subsequent cleavage to the two-cell stage was noted for 95% (38/40) in the treated vs 92.3% (12/13) in the nontreated fertilized zygotes. CONCLUSION: We conclude that PAF treatment of rabbit spermatozoa prior to subzonal insertion improves fertilization rates and may be of clinical significance in assisted reproductive programs.

Animals↗

PubMed1994

Localization of bicarbonate transport along the crypt-villus axis in rabbit ileum.

BACKGROUND/AIMS: HCO3- can be absorbed as well as secreted in the rabbit ileum. With 25 mmol/L HCO3- on the serosal side only, a serosa-to-mucosa flux (Jsm) is found; with 25 mmol/L on the mucosal side only, epinephrine elicits a mucosa-to-serosa flux (Jms). This study aimed to localize these two processes along the crypt-villus axis. METHODS: Excised ileal segments were exposed luminally to 2 mol/L Na2SO4 (hypertonic treatment) or to isotonic Ringer's solution for 15 minutes. Mucosa was then chamber-mounted, and measurements were made of Jsm or Jms and of short-circuit current (Isc) responses to glucose plus alanine and to either theophylline or epinephrine. RESULTS: With HCO3-/CO2 added to the serosal side only, hypertonically treated tissues showed a 22% decline in Jsm; a 25% decline in Isc response to theophylline; and a 71% decline in Isc response to glucose plus alanine compared with control. With HCO3-/CO2 added to the mucosal side only, tissues showed 92% and 87% declines in Jms and Isc responses to epinephrine, respectively, and a 87% decline in Isc response to glucose plus alanine. Histological examination showed destruction of villus caused by hypertonic treatment but sparing of crypt cells. CONCLUSIONS: Both HCO3- and Cl- are secreted mainly by crypt cells and absorbed mainly by villus cells.

Animals↗

PubMed1994

Embryo survival after pronuclear microinjection and trophectoderm biopsy.

OBJECTIVE: Our purpose was to compare murine embryo development after pronuclear microinjection of a gene construct, followed by trophectoderm biopsy at the blastocyst state, with development after a single micromanipulation, and with cultured controls. STUDY DESIGN: alpha-Myosin heavy-chain gene sequence was microinjected into the murine embryo pronucleus and cultured to blastocyst. After trophectoderm biopsy the embryos were allowed to re-expand. Re-expanded embryos were transferred to pseudopregnant females; implantation and live birth rates were recorded. In this study group the rates were compared with three control groups of embryos simultaneously cultured after (1) pronuclear microinjection only, (2) trophectoderm biopsy only, and (3) non-micromanipulated, culture only. RESULTS: A total of 1222 embryos were divided among the four groups. In the study group 472 embryos underwent pronuclear microinjection and trophectoderm biopsy. Of these, 203 (43%) reached the blastocyst stage and underwent biopsy; 183 (38.8%) re-expanded after biopsy. Of 275 pronuclear microinjected only (control 1) embryos, 113 (41.1%) reached the blastocyst stage. Of 336 embryos 148 (44.0%) reached the blastocyst stage and underwent trophectoderm biopsy only (control 2); 129 (39.2%) survived biopsy. The cultured only group (control 3) consisted of 139 pronuclear embryos; 67 (48.2%) developed to the blastocyst stage. CONCLUSIONS: Murine embryos can survive two micro-manipulations, pronuclear microinjection followed by trophectoderm micro-biopsy. Although there is minimal effect of these procedures on embryonic development in vitro, the live birth rate is tenuous.

Animals↗

PubMed1994

Intrauterine insemination in fertile women delivers larger number of sperm to the peritoneal fluid than intracervical insemination.

Randomized IUI or intracervical insemination of eight fertile women with 50 x 10(6) sperm was performed to determine whether IUI delivers more spermatozoa to the peritoneal cavity. After IUI (n = 4), 2,053 to 29,450 sperm were recovered in the PF at laparoscopy. No sperm were found in the PF after intracervical insemination (n = 4). After IUI, CM contained 1.0 x 10(6) to 57.0 x 10(6) sperm/mL; after intracervical insemination, 0 to 1.2 x 10(3) sperm/mL were seen. One therapeutic mechanism for IUI is delivery of larger sperm numbers to the fertilization site by rapid (4 hours) transport. In addition, there is greater retrograde colonization of CM that may result in sustained release of sperm.

Cervix Uteri↗

PubMed1994

Ion transport in rabbit proximal colon: effects of sodium, amiloride, cAMP, and epinephrine.

Effects on ion transport of extracellular Na+ and Cl- ([Na+]o and [Cl-]o, respectively), HCO3(-)-CO2, 8-bromoadenosine 3',5'-cyclic monophosphate (8-BrcAMP), epinephrine, and transport inhibitors were examined in short-circuited rabbit proximal colonic mucosa. Net Na+ flux was independent of Cl- but partially (60%) dependent on HCO3(-)-CO2. Net Cl- flux was partially (70%) dependent on Na+ and totally dependent on HCO3(-)-CO2. Both fluxes peaked between 25 and 60 mM and decreased at higher concentrations. Apical Na+ influx but not Cl- influx obeyed the same pattern. The inhibition resulted from increases in mucosal but not serosal [Na+]o and not from increases in [Cl-]o. Amiloride and benzamil (0.2-0.3 mM) partially inhibited net Na+ absorption, as did 8-BrcAMP, but these effects were independent of the inhibition seen at high [Na+]o. Net Cl- absorption was inhibited by 8-BrcAMP but not by 0.2 mM amiloride. At high [Na+]o and [Cl-]o, there were a residual ion flux suggesting HCO3- secretion and, in the presence of 8-BrcAMP and amiloride or benzamil, net secretions of Na+ and Cl-, the former larger than the latter. Epinephrine, via alpha 2-receptors, reversed the ion-transport effects of high [Na+]o but did not stimulate a mucosal-to-serosal unidirectional HCO3- flux (as shown in rabbit ileum). 4-Acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid (0.5 mM) and bumetanide (10 microM) had no effect on ion transport. The results suggest 1) Na+ entry via two Na(+)-H+ exchangers, one inhibited by amiloride and cAMP and the other inhibited by high [Na+]o and stimulated by epinephrine; 2) Cl- entry via Cl(-)-HCO3- exchange; 3) HCO3- secretion at high [Na+]o and [Cl-]o; and 4) cAMP-induced secretion of Na+ and Cl- at high [Na+]o and [Cl-]o.

Amiloride↗

PubMed1993

Enhanced embryo development of rabbit oocytes fertilized in vitro with platelet activating factor (PAF)-treated spermatozoa.

PURPOSE: The purpose of this study was to determine the effects of PAF treatment of rabbit spermatozoa on in vitro fertilization and subsequent blastocyst formation. Rabbit spermatozoa were exposed to PAF (10(-7) M), lyso-PAF (10(-7) M), or HIS (385 mOsm/kg) for 15 min prior to insemination of ovulated oocytes. Fertilized oocytes were cultured to the hatched blastocyst stage. RESULTS: Fertilization rates with PAF were significantly higher than those of fresh (P < 0.001), lyso-PAF-treated (P < 0.01), HIS-treated (P < 0.05) spermatozoa. Two-cell embryos produced from oocytes inseminated with PAF-treated spermatozoa had significantly higher hatched blastocysts than oocytes inseminated with fresh (P < 0.01), lyso-PAF-treated (P < 0.05), or HIS-treated (P < 0.05) spermatozoa. CONCLUSION: We conclude that PAF treatment of spermatozoa increases fertilization rates and subsequent embryonic development.

Animals↗

PubMed1993

Embryonic platelet activating factor production in the rabbit increases during the preimplantation phase.

OBJECTIVE: This study measured platelet activating factor (PAF) production by rabbit embryos in vitro and ascertained if there is increased PAF production associated with advancing embryonic development. STUDY DESIGN: Two-cell rabbit embryos were recovered from superovulated New Zealand White does and cultured in vitro for 96 hr. Every 24 hr embryos were scored for developmental stage and PAF activity from the corresponding culture medium was measured by platelet aggregation and organic phosphate analyses. RESULTS: PAF was detected in culture medium at all stages from two cells to blastocysts and rose significantly (P < 0.001) at each 24-hr interval, reaching maximal levels at the expanded blastocyst stage. CONCLUSION: Maximal PAF production by expanded blastocysts may be an embryonic paracrine signal that facilitates implantation.

Animals↗

PubMed1993

Platelet-activating factor treatment of human spermatozoa enhances fertilization potential.

OBJECTIVE: The purpose of this study was to evaluate the effects of platelet-activating factor treatment on human spermatozoa fertilizing capability, as assessed by the zona-free hamster penetration assay. STUDY DESIGN: Twenty-three semen specimens were divided into two groups on the basis of initial motile sperm count greater or less than 20 x 10(6)/ml. Each sample served as its own treatment control. Twice-washed spermatozoa were treated with 1 x 10(-7) mol/L of platelet-activating factor before performing the sperm penetration assay. For the two groups the percent penetrations and penetration index were compared with the paired t test, and an independent t test was used to compare parameters between groups. RESULTS: Significant enhancement of both percent penetrations (p < 0.0001) and penetration index (p < 0.005) were noted on platelet-activating factor treatment in both groups. Enhancement of both indices were noted to be independent of initial motile sperm counts. CONCLUSION: Platelet-activating factor treatment of human spermatozoa may be of potential therapeutic value in certain cases of asthenospermia or fertilization failure in human in vitro fertilization.

Female↗

PubMed1993

Bicarbonate secretion in rabbit ileum: electrogenicity, ion dependence, and effects of cyclic nucleotides.

BACKGROUND: Ileal HCO3- secretion is not well understood. The aim of this study was to examine its Na+ and Cl- dependencies, electrogenicity, and responses to amiloride, 4-acetamido-4'-isothiocyano-stilbene-2,2'-disulfonate (SITS), and cyclic nucleotides. METHODS: The serosa to mucosa HCO3- flux (Jsm) across rabbit ileal mucosa mounted between HCO(3-)-free mucosal solution and HCO(3-)-containing serosal solutions was determined by titration. RESULTS: In SO4(2-)-containing Ringer's solution, Jsm varied with [Na+] in two phases, one with a high and one with a low affinity for Na+; amiloride inhibited the high- and SITS inhibited the low-affinity phase. Switching from SO4(2-)- to Cl(-)-containing Ringer's solution caused a SITS-inhibitable 42% increase in Jsm. Changes in Jsm were coupled 3:2 with changes in short-circuit current. Cyclic nucleotide effects on Jsm were as follows. In SO4(2-)-containing Ringer's solution at 141 (but not 80) mmol/L Na+, theophylline caused equal increases in Jsm and short-circuit current that equaled the combined effects of 8-Br-5'-cyclic guanosine monophosphate (cGMP) and 8-Br-5'-cyclic adenosine monophosphate (cAMP). Serosal SITS blocked these effects, but amiloride did not. In Cl(-)-containing Ringer's solution, theophylline and bumetanide together (but not separately) increased Jsm. CONCLUSIONS: (1) Basolateral HCO3- entry occurs via Na+/H exchange and a SITS-inhibitable process (Na(+)-HCO3- cotransport?). (2) Most HCO3- exit across the brush border occurs by a Cl(-)-independent process and some by Cl-/HCO3- exchange. (3) At low cellular [Cl-], HCO3- can be secreted via anion channels activated by cAMP and cGMP. (4) Ileal HCO3- secretion is electrogenic.

4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfo↗

PubMed1991

Treatment of sperm with high-ionic strength medium increases microsurgical fertilization rates of rabbit oocytes fertilized by subzonal placement of sperm.

This study was conducted to investigate the requirement for sperm processing in microsurgical subzonal placement of sperm in rabbit oocytes. Fertilization rates with standard in vitro fertilization and microsurgical subzonal sperm placement were found to be similar (56 and 55%) when sperm treated with high-ionic strength Brackett's defined medium to initiate capacitation were used. Statistically significant reductions in fertilization rates for both standard in vitro fertilization and subzonal placement were noted when twice-washed spermatozoa were used. Initiation of capacitation of spermatozoa results in higher fertilization results even when the zona pellucida is bypassed during fertilization.

Animals↗

PubMed1991

The presence of platelet-activating factor-like activity in human spermatozoa.

Evidence is provided for the existence of platelet-activating factor (PAF)-like activity in the lipid extracts of human spermatozoa. The PAF content of human spermatozoa based on [3H]-serotonin release from washed rabbit platelets was noted to be 1.45 pmol/10(8) sperm cells in highly purified motile spermatozoa. No PAF activity was associated with the seminal fluid. Platelet-activating factor content of spermatozoa may be related to its fertility potential.

Animals↗

PubMed1990

Platelet activating factor enhances in vitro fertilization of rabbit oocytes.

Capacitation of spermatozoa is essential for fertilization. Rabbit spermatozoa are particularly difficult to capacitate in vitro and require treatment with high-ionic-strength Brackett's defined medium. Spermatozoa treated with platelet activating factor had significantly higher fertilization rates when compared with nontreated (fresh, twice washed) spermatozoa (63% vs 34%). Fertilization rates of spermatozoa treated with platelet activating factor, although higher than those of high-ionic-strength capacitated spermatozoa, were not significantly different (63% vs 57%). Spermatozoa treated with lyso-platelet activating factor, the biologically inactive form of platelet activating factor, were noted to have fertilization rates similar to those of the untreated (noncapacitated) group. These data show that synthetic platelet activating factor treatment of uncapacitated spermatozoa induces fertilization of rabbit oocytes in vitro in a manner similar to that for spermatozoa capacitated by high-ionic-strength media and significantly higher than that for untreated spermatozoa or after treatment with the biologically inactive form of platelet activating factor (lyso-platelet activating factor).

Animals↗

PubMed1990

Survival and cell acquisition rates after preimplantation embryo biopsy: use of two mechanical techniques and two mouse strains.

Two strains of mouse embryos at the four- and eight-cell stages had biopsy specimens obtained by means of two different mechanical techniques: aspiration and displacement. Embryos and biopsy specimen cells were evaluated for survival and development. Blastomere acquisition rates were significantly higher with the displacement biopsy technique; however, no difference in survival or developmental rates was found in blastomere biopsy specimens removed from either four-cell or eight-cell embryos. A maximum of one blastomere can be removed from a four-cell embryo, whereas three blastomeres can be taken at biopsy from an eight-cell mouse embryo without significantly affecting embryo development, although mouse strain differences were noted. Intact, viable, biopsied blastomeres will develop in vitro when cocultured with morphologically intact embryos. Births of live offspring after embryo biopsy are reported.

Animals↗

PubMed1989

Spontaneous zona reaction in the mouse as a limiting factor for the time in which an oocyte may be fertilized.

This study evaluated the effect of ovum aging on the in vitro fertilizability of mouse ova. Over 1347 ova were evaluated. Serial trypsin digestion of in vitro and in vivo aged ova revealed an increase in zona digestion time (0.25% trypsin) beginning at 40 hr, which increased over a 40-hr period and resulted in the unfertilized zona becoming as "hard" as the fertilized embryo zona. In vitro fertilizability showed a rapid decrease as zona hardening occurred with loss of cortical granules as assessed by electron microscopy. These data suggest that the window of fertilizability is "closed" by a spontaneous zona reaction occurring at about 55 hr post-human chorionic gonadotropin with loss of cortical granules and zona hardening as manifested by increasing zona digestion time with 0.25% trypsin.

Animals↗