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Biomedical subjects

J Kumar

Publications and source records attributed to J Kumar.

At least 55 records · Page 3Linked to original sources
PubMed1997

Chronic low-dose follicle-stimulating hormone compared with clomiphene/human menopausal gonadotropin for induction of ovulation.

Concurrent administration of clomiphene can reduce the amount of gonadotropins required for induction of ovulation. Recently, follicle-stimulating hormone (FSH) administered in a chronic, low-dose fashion has been reported to give satisfactory pregnancy rates. We compared the conventional clomiphene/human menopausal gonadotropin (hMG) with the chronic, low-dose FSH regimen for induction of ovulation in 87 patients over 110 cycles. The clomiphene/hMG regimen required half the amount of gonadotropin compared to the chronic FSH regimen to achieve follicular maturation. Despite the reduced amount of gonadotropin, the clomiphene/hMG regimen induced a mean fourfold higher level of estradiol production and was associated with significantly greater numbers of large and intermediate-sized follicles compared to the chronic FSH regimen. The proportion of clomiphene/hMG cases with multifollicular development and overstimulation was therefore high (30%). In contrast, the chronic FSH regimen, despite requiring larger amounts of gonadotropin and longer periods of treatment, resulted in unifollicular development, low rates of overstimulation and improved pregnancy rates. We conclude that although clomiphene can reduce the requirement for gonadotropins, the relative safety and effectiveness of the chronic low-dose FSH regimen makes it the method of choice for ovulation induction.

Adult↗
PubMed1996

The first frozen embryo donation pregnancy for hypergonadotrophic hypogonadism in Singapore--hormonal profile and obstetric outcome.

This is the first report in South East Asia of a singleton frozen embryo donation pregnancy for hypergonadotrophic hypogonadism. The hormonal profile was compared with that of a control group of normal uncomplicated singleton pregnancies in Singapore. The plasma beta hCG levels were lower compared to those of our normal uncomplicated singleton pregnancies at 2 to 3 weeks after the embryo transfer but became comparable at 4 to 5 weeks after embryo transfer. The successful vaginal delivery and the obstetric complications developed in this case are discussed.

Adult↗
PubMed1995

Kinectin, an essential anchor for kinesin-driven vesicle motility.

The membrane anchor for the molecular motor kinesin is a critical site involved in intracellular membrane trafficking. Monoclonal antibodies specific for the cytoplasmic surface of chick brain microsomes were used to define proteins involved in microtubule-dependent transport. One of four antibodies tested inhibited plus-end-directed vesicle motility by approximately 90 percent even as a monovalent Fab fragment and reduced kinesin binding to vesicles. This antibody bound to the cytoplasmic domain of kinectin, an integral membrane protein of the endoplasmic reticulum that binds to kinesin. Thus, kinectin acted as a membrane anchor protein for kinesin-driven vesicle motility.

Animals↗
PubMed1995

Characterization of kinectin, a kinesin-binding protein: primary sequence and N-terminal topogenic signal analysis.

Kinectin is a kinesin-binding protein (Toyoshima et al., 1992) that is required for kinesin-based motility (Kumar et al., 1995). A kinectin cDNA clone containing a 4.7-kilobase insert was isolated from an embryonic chick brain cDNA library by immunoscreening with a panel of monoclonal antibodies. The cDNA contained an open reading frame of 1364 amino acids encoding a protein of 156 kDa. A bacterially expressed product of the full length cDNA bound purified kinesin. Transient expression in CV-1 cells gave an endoplasmic reticulum distribution that depended upon the N-terminal domain. Analysis of the predicted amino acid sequence indicated a highly hydrophobic near N-terminal stretch of 28 amino acids and a large portion (326-1248) of predicted alpha helical coiled coils. The 30-kDa fragment containing the N-terminal hydrophobic region was produced by cell-free in vitro translation and found to assemble with canine pancreas rough microsomes. Cleavage of the N terminus was not observed confirming its role as a potential transmembrane domain. Thus, the kinectin cDNA encodes a cytoplasmic-oriented integral membrane protein that binds kinesin and is likely to be a coiled-coil dimer.

Amino Acid Sequence↗
PubMed1994

Brittleness of gallstones to lithotripsy: effect of physicochemical and ultrastructural characteristics.

Why some gallstones do not fragment easily to lithotripsy is unclear. The aim of the present study was to determine gallstone factors associated with resistance to fragmentation. Seventy-six cholesterol rich gallstones were subjected to physical evaluation, in vitro computed tomography, chemical analysis by infra red spectroscopy, and ultrastructural studies (of 26 matched stones) by scanning electron microscopy and energy dispersive X-ray microanalysis. In vitro lithotripsy was performed with the Siemens Lithostar Plus machine at a constant energy level. Of 76 stones, 33 required > 1000 shocks for effective fragmentation (largest diameter < or = 5 mm); they had significantly higher maximum diameter (P < 0.001), volume (P < 0.001), weight (P < 0.001) and lower stone density distribution (SDD) index (P < 0.05) and lower calcium bilirubinate content (P < 0.001) than those requiring < or = 1000 shocks. Large (> 15 mm; P < 0.05), round stones (P < 0.02) and gallstones with SDD index of < 50 HU (P < 0.02) and gallstones with SDD index of < 50 HU (P < 0.05) were more difficult to fragment. Clinical application of these parameters may help in better selection of patients for this non-surgical mode of therapy for gallstones.

Chemical Phenomena↗
PubMed1994

Comparison of the results of bacterial cultures from multiple sites in chronic osteomyelitis of long bones. A prospective study.

We evaluated the results of aerobic, anaerobic, and fungal cultures of specimens that had been obtained from multiple sites in thirty patients who had traumatic osteomyelitis with a sinus track. In each patient, we obtained specimens of material from the sinus track; specimens of purulent fluid, of soft tissue, and of bone obtained from curettage; and specimens from the bed of the involved bone. More than one organism grew on culture of the specimens from twenty-one of the patients; more than three organisms, from those of eleven patients; and ten organisms, from those of two patients. The same organisms grew on culture of the specimens from every site in only fourteen (47 per cent) of the thirty patients. We recommend that specimens of material from the sinus track; specimens of purulent material, of soft tissue, and of bone obtained from curettage; and specimens from the bed of the involved bone be obtained for culture before the treatment of chronic osteomyelitis with a draining sinus, so that as many of the infecting organisms as possible will be identified.

Bacteria, Aerobic↗
PubMed1994

MR in Toxocara canis myelopathy.

We present the case of a 23-year-old woman with cerebrospinal fluid eosinophilia and myelopathy caused by Toxocara canis and describe the clinical and thoracic MR findings. An enhancing thoracic spinal cord lesion which was shown on MR resolved after an interval of 140 days with partial resolution of the patient's symptoms.

Animals↗
PubMed1993

Chemical nature and distribution of calcium compounds in radiolucent gallstones.

A high failure rate for radiolucent cholesterol gallstones to dissolve with oral bile acids may be due to the presence of insoluble calcium compounds. Twenty sets of radiolucent gallstones, 7-20 mm in diameter, obtained from 20 patients undergoing cholecystectomy, were cut, and the outer surface, outer rim, middle portion, and central core areas were scanned for calcium by energy-dispersive X-ray microanalysis (EDX) and scanning electron microscopy (SEM). Scrapings from the four areas of each stone were analysed by infrared spectroscopy. A sample of the crushed stone was used for chemical estimation of cholesterol. Eleven (55%) of the 20 cholesterol (84-96% dry weight of cholesterol) stones showed presence of calcium by EDX; the distribution was peripheral in 5, homogeneous in 4, and central in 2. The chemical compound was calcium bilirubinate in 10 and calcium carbonate in 8 stones. Calcium compounds are present in a high proportion of radiolucent gallstones considered suitable for chemodissolution by conventional criteria. Their unrecognized presence may explain the high failure rate of such stones to respond to medical therapy.

Adult↗
PubMed1993

Stimulation regimens in Assisted Reproductive Technology (ART) programme: experience in the University Hospital, Singapore.

Ovarian stimulation is critical to the success of patients in Assisted Reproductive Technology (ART) programmes. We compared two stimulation regimes retrospectively for ART in the NUH programme. These were the 2:1 and the GnRHa-FSH/hMG regimes. The former was our first-line regime while the latter was used for cycles where there was a prior endogenous LH surge, previous poor response, or an elevated LH level between days three to five of the cycle. All cycles in our ART programme in 1991 were studied, except those for special research procedures, e.g. micro-insemination sperm transfer (MIST) cycles, a total of 241 cycles. Cancellation rates were 14.4% (21 of 146 cycles) and 37.3% (19 of 51 cycles) for the 2:1 and GnRHa-FSH/hMG regimes respectively (p > 0.001). For the 2:1 regime, the majority of cancellations were due to ovulation prior to the oocyte recovery (42.9%; nine of 21 cycles). However, for the GnRHa-FSH/hMG regime, almost all the cancellations were due to poor response (84.2%; 16 of 19 cycles). Fertilisation rates were lower for the 2:1 regime (for both IVF-ER and IVF-TET, where sperm quality was poorer) compared to the GnRHa-FSH/hMG (55.0 and 66.6% respectively; p < 0.001). Pregnancy rates were higher for the 2:1 regime when IVF-ER and IVF-TET were used (16.4% and 23.3% respectively per oocyte recovery, versus 9.8% and 18.8% respectively for the GnRHa-FSH/hMG regime).

Drug Evaluation↗
PubMed1992

Follicular steroidogenesis and oocyte maturation after superovulation of goats (Capra hircus) with gonadotrophins.

Follicles were sampled at three different times after treatment with 1200 iu pregnant mares' serum gonadotrophin (PMSG) or 12 mg ovine follicle-stimulating hormone (FSH), and from untreated control animals. The meiotic status and protein synthesis of the oocyte from each follicle was determined and correlated with the intrafollicular concentration of oestradiol and progesterone. Significantly higher amounts of oestradiol were present in PMSG-treated animals at sponge withdrawal than in FSH-treated and control goats. Twenty hours later, both oestradiol and progesterone concentrations in the PMSG group were higher than those in the FSH group, and were equivalent to control animals at the onset of oestrus. At 18 h after the administration of human chorionic gonadotrophin (hCG), oestradiol decreased markedly in all three treatment groups, whereas progesterone remained significantly higher in PMSG-treated follicles. Although these high concentrations of intrafollicular steroids were associated with a higher incidence of premature condensation of chromatin in oocytes, the two events were not causally related. Moreover, cytoplasmic maturation was not prematurely activated in these oocytes and a changed pattern of protein synthesis was observed in oocytes from all three treatment groups after the hCG injection. Whereas disturbances in follicular steroidogenesis of oestradiol and progesterone occur in vivo in goats superovulated with PMSG, they do not underlie the premature activation of the initial stages of nuclear maturation in oocytes but are associated with normal cytoplasmic maturation.

Administration, Intravaginal↗
PubMed1992

Oocyte maturation and its clinical significance in assisted reproductive technology.

The characteristics and regulation of oocyte maturation in the normal menstrual cycle is reviewed and the mechanisms by which ovarian hyperstimulation with exogenous gonadotrophins, used in assisted reproductive techniques, can disturb this process, is discussed. It is postulated that derangements induced in the maturation of oocytes in the hyperstimulated cycle result in the recovery of poor quality oocytes at egg-pickup which have a reduced potential to undergo normal fertilisation and subsequent embryonic development.

Female↗
PubMed1992

Membrane skeletal protein structure and interactions in human erythrocytes after their treatment with diamide and calcium.

To analyse the role of native structures of membrane proteins in their structural modifications induced by the elevated intracellular free Ca2+ levels, we have studied the Ca(2+)-mediated effects on membrane skeletal proteins in human erythrocytes that were loaded with Ca2+ using the ionophore A23187 after their pretreatment with the sulphydryl oxidizing agent, diamide. The diamide treatment not only induced polymerization of the major membrane skeletal protein, spectrin, in the erythrocytes, but it also promoted intersubunit crosslinking within the tetramers and dimers of this protein. Loading of these diamide-treated cells with Ca2+ failed to induce significant structural modifications of spectrin as well as polypeptide 4.1, another major membrane skeletal protein, as compared to the erythrocytes that were loaded with Ca2+ without the diamide pretreatment. These results have been interpreted to suggest that the Ca(2+)-induced membrane skeletal protein changes in erythrocytes depend on both the shape and relative orientation of these proteins within the membrane skeleton.

Actins↗
PubMed1992

Growth, behavior, development and intelligence in rural children between 1-3 years of life.

In a rural cohort of 625 children registered from 1981 to 1983 in 10 villages of K.V. Block, Varanasi, 196 children were assessed for physical growth, development, intelligence and concept development between 1 and 3 years of age. Home environment was also assessed using Caldwell Home inventory. These rural children remained below 3rd centile of NCHS standard for weight, height, skull and mid-arm circumferences throughout the study. Malnourished children scored poorly in all the areas of development, i.e., motor, adaptive, language and personal social, 9% in Grade I and 16.6% children in Grade II + III had IQ less than 79 (inferior). Concept for color shape and size was poorly developed in malnourished children. Maternal involvement and stimulation was strongly associated with better behavior development and intelligence. Multiple regression analysis showed that the effect of home environment on development and intelligence was of a higher magnitude as compared to status and family variables and nutritional status during 1-3 years of age.

Adult↗
PubMed1991

Luteinizing hormone and follicle stimulating hormone induce premature condensation of chromatin in goat (Capra hircus) oocytes.

This study tested the hypothesis that premature condensation of chromatin in goat oocytes following superovulation with 1200 i.u. pregnant mare serum gonadotrophin (PMSG) is mediated by the high luteinizing hormone (LH) activity inherent in this gonadotrophin. Goats were treated with either a standard (3.95 mL) or high (7.90 mL) dose of a highly purified follicle-stimulating hormone (FSH) preparation (Ovagen), and different doses of human chorionic gonadotrophin (hCG) were added to increase the level of LH bioactivity during superovulation. The meiotic status of oocytes obtained at sponge withdrawal was compared between different treatments and correlated with profiles of LH bioactivity in peripheral plasma. Injection of 100 i.u. hCG (which gave a plasma LH profile comparable to 1200 i.u. PMSG) or 200 i.u. hCG resulted in significantly more oocytes showing premature condensation of chromatin without germinal vesicle breakdown than with 25 i.u. hCG or treatment with FSH alone. Nevertheless, nuclear maturation was also prematurely activated in a significant number of oocytes with a high dose of FSH alone, even though LH bioactivity was not detected in plasma. It is concluded that high LH bioactivity during superovulation of goats with gonadotrophins activates the initial stages of nuclear maturation in oocytes. However, highly purified FSH preparations in high doses can also induce this apparent abnormality in the timing of oocyte maturation through mechanisms unrelated to any LH contamination.

Animals↗
PubMed1991

Changes in dental caries prevalence in upstate New York schoolchildren.

A survey of second and fifth grade children was conducted in upstate New York to determine recent trends in dental caries prevalence. Clinical examinations were conducted on 960 second grade and 837 fifth grade children in 51 schools. A single examiner derived the findings on a uniform basis using a standard protocol. An examination of changes in the percent of caries-free children and mean DMFS/dfs indices revealed that caries prevalence has continued to decline. Although the low SES group in this survey had consistently higher caries levels and a higher treatment need compared to the high SES group, the magnitude of the difference was much smaller compared to the previous survey. Because the sampling was restricted to young children in upstate New York, the trends observed should not be applied to a similar New York City population, to older children throughout New York State, or to children in other states.

Adolescent↗
PubMed1991

Staining of nuclei in fungi by ethidium bromide.

Ethidium bromide, (0.1% solution in ethanol-water, 1:3, v/v) was used to stain nuclei in mycelia and spores of different fungi. Nuclei looked bright brick red under green excitation. This method is very efficient, specific, reproducible and cost-effective.

Cell Nucleus↗