Search PubMed⌕ Search

Biomedical subjects

L Singh

Publications and source records attributed to L Singh.

At least 163 records · Page 9Linked to original sources
PubMed1981

Conserved repeated DNA sequences in vertebrate sex chromosomes.

Satellite DNA isolated from female Elapid snakes contains nucleotide sequences which are quantitatively derived from the W sex-determining chromosome. Certain of these sequences are highly conserved in vertebrates, including mammals, where they are arranged in a sex-specific pattern in Southern blots. Sex reversed mice (Sxr) show a DNA arrangement of these sequences in conformity with their phenotypic sex, suggesting that this DNA is closely connected with the determination of sex. In situ hybridization of the snake sequences with mouse chromosomes reveals a concentration of related DNA at the proximal tip of the mouse Y chromosome. This possible nature and significance of these observations is discussed.

Animals↗
PubMed1980

Sex chromosome associated satellite DNA: evolution and conservation.

Satellites visible in female but not in male DNA were isolated from the snakes Elaphe radiata (satellite IV, p = 1.708 g x cm-3) and Bungarus fasciatus (BK1 minor, p = 1.709 g x cm-3). The satellites cross hybridize. Hybridization of 3H labelled nick translated BK minor satellite DNA with the total male and female DNA and/or chromosomes in situ of different species of snakes revealed that its sequences are conserved throughout the snake group and are mainly concentrated on the W chromosomes. Snakes lacking sex chromosomes do possess related sequences but there is no sex difference and visible related satellites are absent. The following conclusions have been reached on the basis of these results. 1. The W chromosome associated satellite DNA is related to similar sequences scattered in the genome. 2. The origin and increment in the number of the W satellite DNA sequence on the W chromosome is assoicated with the heterochromatinization of the W. 3. Satellite sequences have become distributed along the length of the W and resulted in morphological differentiation of sex chromosomes. 4. Evolutionary conservation of W satellite DNA strongly suggests that functional constraints may have limited sequence divergence.

Animals↗
PubMed1980

Isaptent--a new cervical dilator.

A new cervical dilator, Isaptent, was prepared from granulated Plantago ovata (Isapgol) seed husk. It was evaluated in a multicentric clinical trial for dilatation of the cervix in subjects opting for medical termination of pregnancy. The trial covered 804 women in over 21 centres in different parts of the country. The cases were between 15 to 45 years of age, 0 to 10 parity with a gestation period of 8 to 24 weeks. A single tent was used in 750 subjects and satisfactory dilatation was achieved in 94% of the cases. The cervical dilatation bore no relationship to age, parity and gestation period of the subjects. The tent provided self-lubrication, caused no apparent damage to the cervix and the vaginal flora remained unchanged in the randomly selected subjects in whom bacteriologic studies were performed. The outcome of the clinical trial and advantages of Isaptent over the other procedures used for cervical dilatation are discussed.

Abortion, Induced↗
PubMed1980

Correlation between clinical and radiological diagnosis for fractures and dislocations in an accident department.

Clinicians and radiologists agreed on the presence or absence of fracture or dislocation in 897 of 1011 cases (89%). The agreement was closer in cases that were thought on clinical grounds to show no injury. We think the high incidence of agreement in this group should help to reduce the number of radiographs used in an accident department. Further analysis of the results indicates which areas of the body have most missed fractures.

Adolescent↗
PubMed1980

An estimation of reproductive performance in the women of Punjab.

This paper reports the preliminary findings on the reproductive performance of 325 Punjabi women between the age limits 35 and 55 years. The total amount of time available for reproduction and total time used for effective reproduction and the period which has been wasted as a result of socio-cultural and biological factors have been calculated in the study in hand. For the purpose of the present study it has been assumed that the time period between menarche and menopause represents the maximum possible length of potential reproductive life. A mean age at menarche of 14.31 years and mean age at menopause of 44.6 years gives an average length of menstrual life of 30.3 years for the cases studied. The mean age at marriage in this sample is 14.60 years. A total of 10,084.20 years were all the reproductive periods of 325 individuals. It has been observed that out of this period only 8,782.90 years (87.08 per cent) have been used for effective reproduction and 1,201.3 years (12.92 per cent) have been wasted as a result of socio-cultural and biological factors. All pregnancies, as well as breast feeding operate to reduce fecusidability. The various contraceptive measures used by mankind also lower reproductive performance.

Adult↗
PubMed1980

Trend of menopause among the women of Punjab.

The paper presents a report on mean age at menopause among 325 women belonging to nine endogamous groups, i.e. Jat Sikh, Baniya, Arora, Brahmin, Khatari, Gujar, Hindu Harijan, Sikh Harijan and Backward Classes of Punjab. The results thus obtained are compared with the findings of other such studies.

Adult↗
PubMed1979

Behaviour of sex chromosome associated satellite DNAs in somatic and germ cells in snakes.

Sex chromosome associated satellite DNAs is isolated from the snakes Elaphe radiata (sat III) (Singh et al., 1976) and Bungarus fasciatus (Elapidae) (minor satellite) are evolutionarily conserved throughout the suborder Ophidia. An autosome limited satellite DNA (B. fasciatus major satellite) is not similarly conserved. Both types of satellites have been studied by in situ hybridisation in various somatic tissues and germ cells where it has been observed that the W sex chromosome remains condensed in interphase nuclei. In growing oocytes however, the W chromosome satellite rich heterochromatin decondenses completely whilst the autosomal satellite rich regions remain condensed. Later, the cycle is reversed and the W chromosome condenses whilst the autosomal satellite regions decondense. In a primitive snake (Eryx johni johni) where the sex chromosomes are not differentiated and where there is no satellite DNA specific to them, these phenomena are absent. - The differential behaviour of autosomal and sex chromosome associated satellite DNAs is discussed in the light of gene regulation.

Animals↗
PubMed1977

Effect of different denaturing agents on the detectability of specific DNA sequences of various base compositions by in situ hybridisation.

In situ hybridisation of certain AT rich and GC rich satellite DNA complementary RNAs (cRNAs) to their homologous chromosomes at their respective optimal rate temperatures (TOPTS) after denaturation with various reagents (0.2 N HCl, 0.07 N NaOH, 90% formamide and heat) led to the following conclusions. -- Heat denaturation of chromosomal DNA in 0.1 X SSC at 100 degrees C gives significantly higher grain counts regardless of DNA base composition, HCl denaturation discriminates markedly against GC rich DNA. Chromosome morphology is best preserved after HCl and heat denaturation.

Animals↗
PubMed1976

Satellite DNA and evolution of sex chromosomes.

The satellite DNA (SATELLITE III) which is mainly represented in the female of Elaphe radiata (Ophidia, Colubridae) has been isolated and its buoyant density has been determined (delta equals 1.700 g cm-3). In situ hybridisation of radioactive complementary RNA of this satellite DNA with the chromosomes of different species has revealed that it is mainly concentrated on the W sex chromosome and its sequences are conserved throughout the sub-order Ophidia. From hybridisation studies these sequences are absent from the primitive family Boidae which represents a primitive state of differentiation of sex chromosomes. Chromosome analysis and C-banding have also revealed the absence of heteromorphism and of an entirely heterochromatic chromosome in the species belonging to the primitive family and their presence in the species of highly evolved families. It is suggested that the origin of satellite DNA (satellite III) in the W chromosome is the first step in differentiation of W from the Z in snakes by generating asynchrony in the DNA replication pattern of Z and W chromosomes and thus conceivably reducing the frequency of crossing-over between them which is the prerequisite of differentiation of sex chromosomes. Presence of similar sex chromosome associated satellite DNA in domestic chicken suggests its existence in a wider range of vertebrates than just the snakes.

Animals↗
PubMed1976

The chromosomal localisation of satellite DNA in Ptyas mucosus (Ophidia, Colubridae).

Ptyas mucosus male DNA has a repetitious DNA satellite (p = 1.700 g cm-3) constituting 5% of the haploid genome. In situ hybridisation of radioactive complementary RNA (cRNA) has revealed that satellite sequences are located in the centromeric region of one pair of macrochromosomes and in the terminal region of 8 pairs of microchromosomes. These regions are constitutively heterochromatic as revealed by C-banding. The possibility of involvement of satellite rich microchromosomes in nucleolus organisation is discussed.

Animals↗
PubMed1975

Anti-immunoglobulin analysis by diffusion patterns of inhibition and facilitation of complementary lysis in agar. II. Diffusion-lysis as a method for recognizing in vivo immunosuppressive activity of anti-immunoglobulins.

This paper provides evidence that it is possible to prepare facilitating anti-mouse immunoglobulin (that is, anti-mouse immunoglobulin which facilitates complementary lysis of red cells sensitized with mouse-produced haemolysin) which, when injected into mice 24 hours before an injection of sheep red cells, very markedly reduced the number of haemolysin-producing cells detectable in spleen four days later. The diffusion-lysis method was used to recognize this and other anti-Ig's in heterologous antiserum and fractions thereof. The effective antibody was in the gamma2 fraction of antiserum produced in guinea pigs by injecting them with guinea pig red cells sensitized with mouse-produced haemolysin. This method of immunizing was used in order to stimulate the production of antibody against immunoglobulin which had undergone the configurational change characteristically occurring when antibody unites with antigen. The 19S fraction of the antiserum contained inhibiting anti-mouse immunoglobulin (anti-mouse immunoglobulin which inhibits complementary lysis of red cells sensitized with mouse-produced haemolysin) and interfered with immune depression by the gamma2 fraction. It is postulated that the gamma2 fraction induces complementary lysis only of lymphocytes whose surface immunoglobulin receptors have bound antigen and undergone configurational change. It is suggested that facilitating anti-immunoglobulin of the type described is responsible for immune suppression by anti-lymphocyte serum (ALS). Facilitating anti-mouse immunoglobulin was demonstrated in two samples of ALS (anti-mouse) which were active in suppressing graft rejection, but inhibiting anti-mouse immunoglobulin only was found in a sample which was ineffective in suppressing graft rejection.

Agar↗
PubMed1975

A study of some genetic markers in the Bahawalpuris of Patiala, India.

ABO blood groups, secretor factor, Rh-factor, and PTC taste ability have been examined in 360 individuals of Bahawalpuri population of Patiala. B and O blood groups are more frequent (44.46% & 31.36% respectively). Frequency of secretors (84.72%) outweighs that of nonsecretors (15.28%). All the individuals have been found to belong to Rh--ve type. High incidence of nontasters (55.55%) has been seen. Genes r, Se, D, and t are found to be most frequent in the population.

ABO Blood-Group System↗
PubMed1975

Mid-phalangeal hair, hand clasping and handedness among Khatris and Baniyas of Patiala, India.

Mid-phalangeal hair, hand clasping and handedness have been examined in 425 adult subjects from two endogamous groups of Patiala, Hindu Khatris (230) and Baniyas (195). In a majority of subjects (53.73% in males and 46.35% in females) mid-phalangeal hair appears to be completely absent. The highest frequency of this trait is found in the combination III-IV and, when considering individual digits, on IV (around 50%). As for hand clasping, R-type appears to be more frequent in Khatris and L-type in Baniyas. Right handedness appears to be by large more frequent in both groups and sexes.

Female↗