Biomedical subjects

K Gopalkrishnan

Publications and source records attributed to K Gopalkrishnan.

At least 19 recordsLinked to original sources

PubMed2000

Constraints in the development of contraceptives for men.

Considerable efforts have been made to develop a male contraceptive and the studies have provided very useful information in this field. At least five different strategies to develop a male contraceptive have been pursued, namely: inhibition of sperm production, interference with sperm function, interruption of sperm transport, prevention of sperm deposition, and prevention of sperm-egg interaction. Of all these approaches, inhibition of sperm production by using androgens either alone or in combination with progestins have given the most encouraging results. A number of clinical trials substantiate that it is indeed possible to have a reversible, effective and safe hormonal method of contraception. A postmeiotic and epididymal approach to interfere with sperm function or the secretory and metabolic processes of the epididymis is another attractive option of male contraceptive development. A number of chemical compounds have been identified which interfere with sperm function in the epididymis without affecting sperm production, however, the compounds evaluated so far were found to be toxic. Interruption of sperm transport through the vas either by vasectomy or percutaneous intravasal injection of liquids which form cure-in-place plugs is also an attractive option. However, reversibility of the methods is of concern in their wide scale use. The major constraint in developing a long-acting male contraceptive seems to be the need for greater investment for product development. The clinical trials for evaluating the efficacy and safety of the new products and formulations stretch over several years and require enormous financial commitment. Nevertheless, the long-term gain of having a long-acting reversible contraceptive for men is far greater than the financial commitments over few years. Male attitude towards using methods of family planning is much more favourable than originally believed. The pharmaceutical industry as well as the health care providers therefore have a greater responsibility. For early development of a contraceptive for men, it is essential to increase investment and simplify the drug regulatory procedures. The advent of newer technologies coupled with the convergent efforts of scientists will certainly make it possible to have an effective, safe and reversible male contraceptive in the near future.

Contraception↗

PubMed1999

Use of acridine orange to evaluate chromatin integrity of human spermatozoa in different groups of infertile men.

To study the sperm chromatin compactness various methods, such as acidic aniline blue or acridine orange staining, have been applied. Due to its metachromatic properties, acridine orange dye fluoresces green with double- and red with single-stranded DNA. Samples (n = 181) were evaluated and grouped as follows: group I, normal recently fertile; group II, male having female partner with repeated early pregnancy loss; group III, male with varicocele; and group IV in-vitro fertilization and intrauterine insemination failures. Routine semen analyses were carried out in all the cases. Amorphous particulate matter as observed under phase contrast microscope was graded on the scale of nil to +4. Fixed smears were stained with an aqueous solution of acridine orange and viewed under a fluorescence microscope. Two hundred cells were counted and the percentage of fluorescence calculated. Groups II, III and IV exhibited significantly low green fluorescence compared with the control group. The study also indicates that increased amorphous particulate matter (indicating infection) might be one of the contributing factors to lower acridine orange stainability. Thus acridine orange staining can be used to evaluate the integrity of the nucleus, disorders of which can cause unexplained infertility or lower fertilization potential that may go undetected by routine analysis.

Acridine Orange↗

PubMed1998

Tamoxifen-induced light and electron microscopic changes in the rat testicular morphology and serum hormonal profile of reproductive hormones.

The effects of oral administration of tamoxifen at doses of 40 and 200 micrograms/kg/day on testicular histology, testicular ultrastructure and serum hormonal profile were studied. The drug was administered to adult male rats over a period of 90 days and the effect was assessed at 10-day intervals. The morphometry, microscopic structures of the testis, including ultrastructure and daily sperm production rate, were evaluated. The hormone profiles of luteinizing hormone (LH), follice-stimulating hormone (FSH), testosterone, and estradiol were studied. The testes from treated animals showed disorganization of tubular elements with increased intercellular space. At day 50, the changes were extensive including presence of phagosomes. Morphometric studies showed a reduction in the spermatid and spermatozoan population (69.3%) with no changes in tubular diameter. The mean Leydig cell area was significantly lowered at day 50, at both doses. The daily sperm production rate was reduced as compared with controls. An array of degenerative changes were revealed by ultrastructural studies. The changes were extensive at day 50 at both doses. The characteristic features were lost in most of the cells with phagolysosomes becoming abundant. The cytoplasm of the cells was dense with poorly defined cytoplasmic organelles. Circulating LH levels were not modified at the 40 micrograms/kg/day dose but at 200 micrograms/kg/day, LH levels were significantly decreased. Initial transitory rise in FSH was seen with both doses. Both doses of tamoxifen decreased testosterone levels. Changes in the circulating estradiol levels were inconsistent, and no apparent relationship between dose and days of treatment was observed. Thus, this study supports our thesis of tamoxifen as a potential male contraceptive agent.

Animals↗

PubMed1995

Onapristone (ZK 98.299): a potential antiprogestin for endometrial contraception.

OBJECTIVES: The effects of the antiprogestin onapristone (ZK 98.299) on fertility; menstrual cycle length; duration of menses; serum estradiol, progesterone, and cortisol concentrations; and endometrial morphologic features were studied in adult bonnet monkeys. STUDY DESIGN: Five animals were treated subcutaneously with the vehicle and another nine with either 2.5 (n = 4) or 5 mg of onapristone per animal (n = 5). Treatment was initiated on day 5 of the first treatment cycle, and thereafter onapristone was administered every third day for four to seven consecutive cycles. The females were placed with adult males during the periovulatory period, which was assessed by frequent analysis of serum estradiol concentrations. In the final treatment cycle an endometrial biopsy was performed on day 8 after a midcycle estradiol peak in the ovulatory cycle, or around day 20 if the cycle was anovulatory. Blood samples for estradiol, progesterone, and cortisol measurement were collected every third day, except for the periovulatory period when sampling was more frequent. RESULTS: Each of the five animals treated with the vehicle became pregnant: one in the first, three in the second, and one in the third mated cycle, whereas only one of nine treated with onapristone became pregnant. Four animals treated with 2.5 mg of onapristone for 17 cycles and another four treated with a 5 mg dose for 21 cycles did not conceive. In eight animals that did not conceive the first three treatment cycles of six were ovulatory, and in the remaining two animals two cycles of each were ovulatory. During treatment the mean menstrual cycle length was not altered significantly; however, in one it was shortened and in another two it was prolonged. Similarly, the mean duration of menses was not significantly affected, but in some cycles it was reduced. Moreover, there was only slight bleeding in some treatment cycles. Ovulation occurred in 30 of 45 treatment cycles, including the final treatment cycle during which the biopsy was taken, as indicated by serum estradiol and progesterone concentrations. In some of the ovulatory cycles prolonged treatment suppressed luteal activity; however, in the ovulatory cycles the duration of follicular and luteal phases was not significantly affected. In the anovulatory cycles there was a delayed increase in serum estradiol concentrations, suggesting a partial inhibition of folliculogenesis. In treated animals endometrial growth and development was retarded and rendered out of phase. In animals treated with the higher (5 mg) onapristone does the endometrial glands had partially regressed, the secretory activity was blocked, and stromal compaction was evident. The treatment had no significant effect on serum cortisol levels. CONCLUSIONS: This study demonstrates that low-dose onapristone treatment throughout the menstrual cycle prevents pregnancy without disturbing the menstrual cycle and ovulation in the majority of cycles. However, anovulation and luteal insufficiency occurred in some animals during prolonged treatment. The contraceptive effect in the ovulatory cycles seems primarily related to the retardation of endometrial development resulting in the inhibition of endometrial receptivity. It appears likely that a dose or treatment regimen of onapristone that will inhibit endometrial receptivity and prevent implantation without affecting the menstrual cycle even on prolonged treatment could be identified.

Animals↗

PubMed1995

Severe asthenozoospermia: a structural and functional study.

Ejaculates from 25 patients with severe asthenozoospermia (all spermatozoa immotile or only non-progressively motile) were studied to identify individually the cause of impaired motility. Multiple tests were performed, viz. light and electron microscopic studies and sperm function tests. An objective scoring was applied to both the routine and the functional analyses. Three categories of samples were identified: (1) necrozoospermia (n = 9), where sperm viability was very poor; (2) structural tail abnormality as seen by light microscopy (n = 4); and (3) ultrastructural abnormality (n = 12). In the last category, one case showed absence of dynein arms; this was associated with mitochondrial abnormalities. Mitochondrial abnormality with normal tail components was observed in the majority (n = 7) and accessory fibre abnormality in four cases. The scoring system revealed that, functionally, all samples were abnormal whereas routine analysis showed 15 samples to be subnormal and 10 to be abnormal, which indicates the need for functional analysis. Because of the multiple defects seen in these samples, there is a need for a battery of sperm function tests. This study indicates that mitochondrial defects are one of the causes that may account for the loss of sperm motility in the patient population.

Acrosome↗

PubMed1995

Efficiency of routine semen analysis to predict functional and structural integrity of human spermatozoa.

The study is to examine the ability of routine semen analysis to predict the functional and structural integrity of spermatozoa in in vitro conditions. Since large number of subjects were evaluated over a long period of time, the value of routine analysis to prognosticate the functional and structural integrity in the same sample was assessed. Routine semen analysis was done on 354 subjects. In the same sample, functional tests were carried out. The functional tests applied were hypoosmotic swelling test, test for acrosome intactness, nuclear chromatin decondensation test and sperm mitochondrial activity index. A scoring system was adopted for both routine and functional analysis. According to the scores obtained, the samples were categorized into fertile, subfertile and infertile. Analysis of the data indicated that efficiency of routine semen analysis was 38.13%. Prediction of functional integrity by routine analysis of semen specially in subnormal cases is only partly fulfilled. The study also indicates that functional tests are definitely indicated in cases with subnormal score.

Humans↗

PubMed1993

Effects of tamoxifen on the fertility of male rats.

The effects of oral administration of tamoxifen (a synthetic non-steroidal anti-oestrogen) at doses of 40, 200 or 400 micrograms kg-1 day-1 on the circulating concentrations of LH, FSH, prolactin, testosterone and oestradiol, weights of pituitary, testes, secondary sex organs and the fertility of adult male rats were determined. The drug was administered per os daily, for up to 90 days. The fertility of rats treated with tamoxifen for 60, 70, 80 or 90 days was assessed by allowing them to mate with normal female rats of proven fertility. Tamoxifen at 40 micrograms kg-1 day-1 reduced concentrations of testosterone in plasma but had no affect on LH, FSH, prolactin and oestradiol concentrations, and the weights of pituitary, testes, epididymides, ventral prostate and seminal vesicles. Tamoxifen at 40 micrograms kg-1 day-1 reduced potency, fecundity, the number of implantation sites, the fertility index and litter size. Tamoxifen at 200 and 400 micrograms kg-1 day-1 reduced the concentrations of LH and testosterone in plasma and the weights of testes and secondary sex organs compared with controls. Tamoxifen at 400 micrograms kg-1 day-1 was most effective in reducing the number of viable pups, the litter size (< or = 1) and the fecundity (20%). The potency of treated rats (a measure of the presence of an ejaculate) was significantly decreased when compared with controls, but copulation was apparently not affected as mated female rats showed a constant dioestrous phase. Histology of the testes revealed disorganization of the cytoarchitecture of the tubules with obliterated lumen.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Passive immunization against prostatic 'inhibin' peptide as a male contraceptive.

Passive immunization of adult male hamsters for 12 weeks against peptide (As-PIP), a sperm coating antigen, resulted in selective elevation of the blood levels of FSH, impairment of spermatogenesis, and complete infertility when males were mated with normal cycling females. Passive immunization of male marmosets with As-PIP for 8 weeks was also effective and was reversible, without causing any obvious change in mating behaviour. These preliminary studies in hamsters and marmosets indicate that antibodies to a prostatic 'inhibin' peptide represent a promising new approach to male contraception.

Animals↗

PubMed1992

Volume of semen as a parameter of its quality.

A total of 1655 semen samples obtained from men who underwent initial semen analysis before enrolling for IVF-ET programme were analysed. The semen samples were categorized arbitrarily on the basis of volume as high (> 4.5 ml), normal (1.5-4.5 ml) and low (< 1.5 ml). The semen parameters studied vis-a-vis volume of the sample were viscosity, osmolality, motility, sperm count and morphology. The different volume groups were also compared to the overall quality of the sample. The study showed that high and low volume semen were associated with high incidence of spermatozoa exhibiting subfertile characteristics. Normal volume per se did not indicate the quality of the sample, however high and low volumes were indicators of semen of subfertile quality. There was an inverse correlation between osmolality and volume of semen sample. Thus the parameter 'volume' gives a rough estimate of the quality of the sample.

Humans↗

PubMed1992

Antifertility effects in rats actively immunized with 80 kDa human semen glycoprotein.

A 80 kDa human sperm antigen has been identified using the serum of an infertile woman having circulating antisperm antibodies. The antigen was then purified to homogeneity by gel permeation chromatography using HPLC (protein PAK-125 column) system and on FPLC (superose-12 column) system. The antigen was found to be a glycoprotein. The antigen was mainly localized in the postacrosomal region of the human sperm, while it was localized in the head region of the rat sperm as demonstrated by immunofluorescent staining. The presence of this antigen was also demonstrated in the human prostate and endometrium and in the rat testis; epididymis and the prostate by immunocytochemical staining. The purified protein upon active immunization in female rats caused infertility in 100 percent animals. While in male rats it caused infertility in 90 percent animals. On morphometric analysis of testicular tissue it was observed that there was no significant change in spermatogonia and spermatocytes, but significant decrease in spermatids and sperm number as well as daily sperm production in the immunized male rats. The epididymal spermatozoa were markedly reduced in number and were largely found to be agglutinated. The results suggest that 80 kDa human sperm antigen appears to be a suitable candidate for immunocontraception both in male and female.

Animals↗

PubMed1992

Incidence of abnormalities in sperm morphology as an indicator of its fertilizing potential.

A retrospective analysis was carried out to assess the correlation of sperm morphology with the occurrence of fertilization in vitro of human oocytes. Seventy women who were subjected to in vitro fertilization procedure were taken up for this study. The cytological smears of semen were evaluated for the morphological characteristics of spermatozoa. Instances where in vitro fertilization did not occur (group II) had significantly (P less than 0.001) higher morphological abnormalities (head defects) when compared with those where fertilization occurred in vitro (group I). The results indicate that evaluation of sperm morphology with special reference to head abnormalities has diagnostic potential in human in vitro fertilization.

Adult↗

PubMed1991

Effects of intranasal administration of norethisterone on folliculogenesis, cervical mucus, vaginal cytology, endometrial morphology and reproductive-endocrine profile in women.

The effects of intranasal administration of norethisterone (NET) on menstrual cycle length, folliculogenesis, serum levels of estradiol, FSH, LH and progesterone, vaginal cytology, cervical mucus and endometrial morphology were studied in 8 volunteers (age 28 to 39 years, weighing between 46 and 54 kg). The study period comprised 4 consecutive menstrual cycles. In the first cycle (pretreatment cycle), only the vehicle (alcohol, propylene glycol, water; 3:3:4) was sprayed intranasally (100 microliters in each nostril), using a metered nebulizer, once daily from day 3 to the last day of menstrual cycle. In the next two cycles (treatment cycles), NET (300 micrograms/day) was administered once daily, starting from day one of menstrual cycle, between 9 and 10 a.m. The fourth cycle was a post-treatment cycle in which the volunteers were monitored for recovery. Blood samples (about 5 ml each) were collected once daily from day 8 to 24 and thereafter on alternate days until the last day of cycle during all the 4 cycles. Levels of estradiol, FSH, LH and progesterone were measured in the serum samples by radioimmunoassay methods. Cervical mucus samples and vaginal smears were collected once daily starting from day 7 or 8 of each cycle until the mucus was very scanty. Serial pelvic ultrasonography was performed starting from day 7 or 8 until the growing follicle disappeared or throughout the cycle in case a growing follicular cyst was observed. Endometrial aspirates were collected once around day 22 in each cycle and processed for routine histological examination.

Administration, Intranasal↗

PubMed1991

Comparison of four different ovarian stimulation protocols in an in vitro fertilisation & embryo transfer programme.

Four different ovarian stimulation protocols were evaluated in an in vitro fertilisation and embryo transfer programme in 208 women (228 treatment cycles). In the rigid protocol (RP), 100 mg of clomiphene citrate (CC) was given from day 3 to day 7 of the menstrual cycle and 300 IU of human menopausal gonadotropin (hMG) was given from day 5 of the menstrual cycle. In the individualised protocol (IP) the same drugs and doses were used as in RP, but the day of initiation of CC depended on the length of the individual's menstrual cycle and hMG was administered from the last day of CC. In the programmed protocol (PP), ovarian function was suppressed with oral contraceptive pills (ethinyl estradiol 30 micrograms and norethisterone 1 mg) started on day 5 of the menstrual cycle for 45 to 70 days. Considering the last day of pill intake as day 0, CC was given for 5 days from day 5 and hMG (300 IU) from day 7. In the alternate day protocol (ADP), 100 mg of CC was administered from day 2 to day 6 and hMG (300 IU) was given on alternate days from day 2 to day 8 or day 10 of the cycle. In all the women, hCG (5000 IU) was administered when the diameter of at least 2 follicles was greater than or equal to 16 mm and estradiol levels were 300 pg/ml/dominant follicle. Patients not showing such a response were not treated further. The cardinal events of IVF-ET such as number of good responders, incidence of oocytes harvested, fertilised and embryos transferred per cycle were compared and it was concluded that the pregnancy rates were highest in women treated by the PP.

Adult↗

PubMed1990

Effect of antibodies to human seminal plasma inhibin on spermatogenesis and sperm agglutination in adult male rats.

In vitro incubation of rat epididymal sperm with antiserum to human seminal plasma inhibin (As hSPI) caused agglutination of the sperm. In vivo administration of As hSPI to adult male rats resulted in a significant decrease in testicular as well as epididymal sperm counts. Furthermore, the majority (almost 90%) of the epididymal sperm were agglutinated. When these animals were mated with normal cycling females, significant reduction in fertility was observed.

Animals↗

PubMed1990

Semen characteristics of asymptomatic males affected by Trichomonas vaginalis.

Trichomonas vaginalis is a sexually transmitted anaerobic parasite which causes vaginitis and cervicitis. The present study was carried out to determine the incidence of Trichomonas infection in semen samples of asymptomatic men and also to understand the changes of semen characteristics in the infected individuals before treatment and after treatment with metronidazole (Flagyl, 400 mg x 3x a day for 10 days). The semen obtained from 1131 men was examined for different characteristics and Trichomonas were detected in wet smear preparations in 50 cases (4.42%). The characteristics of semen in them was compared with 52 normal semen samples. Statistical analysis showed that the seminal fluid viscosity and percentage particulate debris was increased significantly in the infected group (P less than 0.001). There was no significant change in the pH of semen. Spermatozoan motility and morphologically normal forms were decreased significantly (P less than 0.001), spermatozoan viability was altered, and there was a significant change in membrane integrity (P less than 0.001) as indicated by the hypoosmotic swelling test. The significant improvement in semen characteristics were seen in 25 cases after a single course of treatment. Therefore, it is possible that in some cases, the infertility seen in asymptomatic individuals may be due to infection by Trichomonas.

Female↗

PubMed1990

Scanning electron microscopy in the assessment of sperm morphology.

The advantages of using scanning electron microscope (SEM) vis-a-vis light microscope (LM) to assess sperm morphology was studied. The semen samples obtained from 15 fertile (group I) and 25 infertile (group II) men were processed by routine procedures for LM and SEM. The usually described sperm abnormalities were identifiable with greater resolution. Sperm abnormalities were significantly more in group II, as compared with group I (P less than 0.001) by both methods. Abnormalities of different regions, like thinning of midpiece, were scored higher in SEM than in LM. The abnormality of aggregation or retraction of mitochondrial sheath was clearly visible under SEM and missed by LM. Apart from detection of certain subtle abnormalities, SEM has advantages of rapid screening, accurate quantitation directly from the screen, zooming to higher magnification and automation.

Humans↗

PubMed1989

Presence of sperm antibodies and association with viscosity of semen.

Semen characteristics were studied in 96 men from an in-vitro fertilization and embryo transfer programme. Along with the routine semen analysis, the presence of sperm antibodies in seminal plasma was measured by an ELISA technique. Antibodies to spermatozoa (IgA and/or IgG) were present in 19 cases and 15 of these (78.95%) had abnormally high viscosity, often associated with a high percentage of particulate debris and an increased number of morphologically abnormal spermatozoa.

Antibodies↗

PubMed1989

Modulation of prolactin release by a 25 kD peptide of human seminal plasma.

Prolactin-regulating factor (PRF) of molecular size of 25 kD has been isolated from human seminal plasma. This 25 kD factor inhibits circulating PRL levels in intact adult male rats to the extent of about 48% at dose level of 10 micrograms. Furthermore, in vitro incubation of pituitary demonstrated that PRF inhibits the release of PRL in the medium. PRF also interferes with the binding of I125 PRL to its receptors in liver, prostate, and spermatozoa. However, I125 PRF itself does not bind to these receptors. PRF seems to modulate PRL release as well as its binding to receptors. A sensitive, specific RIA was developed for PRF. Using the RIA, levels of PRF in seminal plasma were measured. PRF levels were low in vasectomized subjects as compared with controls. A negative correlation was noted with seminal plasma PRF levels and sperm count.

Animals↗