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Biomedical subjects

K Krishan

Publications and source records attributed to K Krishan.

At least 19 recordsLinked to original sources
PubMed2005

Dynamic Id2 expression in the medial and lateral domains of avian dermamyotome.

Id2 cDNA was isolated from a subtractive screen of stage-12 quail caudal somites. In situ hybridisation analysis identified the previously un-described expression of Id2 mRNA in distinct medial and lateral domains of the somitic dermamyotome in both quail and chick embryos. Id2 expression in somites was highly dynamic being first initiated in the lateral domain of the dermamyotome of stage-8-10 embryos, followed by expression in a separate medial domain. Id2 mRNA during subsequent embryonic development could be detected in both medial and lateral domains in the anterior to mid regions while the posterior, recently segmented somites, showed expression only in the lateral domain, which was eventually down regulated in the anterior-most somites. Tissue manipulation studies revealed that Id2 expression in somites required positive signalling from not only axial structures and lateral plate mesoderm but also surface ectoderm. In addition, Id2 expression was also observed in anterior and posterior domains of developing avian limb buds and interdigital tissue.

Animals↗
PubMed2000

Slow troponin T mRNA in striated muscles is expressed in both cell type and developmental stage specific manner.

We have cloned cDNA sequences of both rat and mouse slow troponin T gene. These sequences share a high level of homology with each other and with the human slow troponin T gene although we were unable to detect an alternatively spliced exon present at 3' end of human slow troponin T cDNA in either mouse or rat cDNAs. Northern blot analysis detected a high level expression of slow troponin T in adult mouse Soleus with a lower level expression in mixed postnatal skeletal muscles. Unlike late fetal and postnatal skeletal muscles in which slow troponin T expression is restricted to slow muscle fibre rich regions only, in situ hybridisation analysis detected this isoform to be highly expressed in somitic myotome and all muscle masses at 10-14 days of gestation after which its expression was rapidly downregulated. The unexpected expression of slow troponin T mRNA in fetal heart was apparent by both northern blotting and in situ hybridisation analyses. Slow troponin T mRNA in fetal heart was first detected at 10 day in utero reaching maximum levels of expression at 12-15 days gestation. The slow troponin T in the heart was mainly expressed in the ventral ventricles until day 15 after which low level expression was also observed in both atria. Slow troponin T mRNA in both atrium and ventricle was mainly expressed in outer wall of the myocardium although it was also expressed in interventricular septum. This study therefore shows that in addition to being a cell type specific marker during later fetal and postnatal skeletal muscle development, slow troponin T represented one of the major developmental isoforms expressed in embryonic and fetal skeletal muscle as well as in the cardiac muscle.

Age Factors↗
PubMed1996

Changes in some troponin and insulin-like growth factor messenger ribonucleic acids in regenerating and denervated skeletal muscles.

To investigate the role of innervation and to determine if the process of muscle differentiation is preprogrammed, the expression of insulin-like growth factors (IGF-I and IGF-II), troponin I and troponin T mRNAs was studied in regenerating transplants of rat Extensor digitorum longus muscle in the presence and absence of nerve. The role of innervation was further investigated by denervating some adult fast (Gastrocnemius and Plantaris) and slow (Soleus) skeletal muscles. In normal adult skeletal muscles, IGF-I, IGF-II and developmental fast troponin T mRNA containing exon y, are undetectable or present at very low levels. Induction of all these mRNAs was observed in regenerating muscles in both the presence and absence of nerve as well as following denervation of adult fast and slow skeletal muscles. Their low level expression was maintained in adult denervated skeletal muscles but gradually suppressed in both innervated and noninnervated regenerating extensor digitorum longus muscle transplants after 2 months. Fast troponin T mRNA was synthesized in both innervated and noninnervated EDL transplants although the level of this transcript changed markedly in response to denervation of both adult fast and slow skeletal muscles. The fast troponin T mRNA containing exon 17 was also initially expressed in both regenerating muscles but its level was reduced with time in both transplants and in all adult denervated skeletal muscles. Fast and slow troponin I mRNAs were synthesised during EDL muscle regeneration in both the presence and absence of nerve but the slow troponin I expression was not maintained in noninnervated transplants. The level of fast troponin I mRNA decreased in denervated fast skeletal muscles but markedly increased in denervated Soleus. The level of slow troponin I mRNA was slightly increased in denervated fast skeletal muscles but considerably reduced in denervated Soleus.

Animals↗
PubMed1989

Circannual rhythmicity in the occurrence of idiopathic priapism in north-western India.

A group of 26 patients who were operated upon for idiopathic priapism between 1972 and 1986 were classified according to the date on which they attended hospital. During the same 15-year period 150 patients with penile cancer were treated and they served as controls. The data were analysed for circannual rhythmicity (365.25 days = 360 degrees and 0 degrees = 22 December. This revealed a significant circannual rhythmicity in the occurrence of idiopathic priapism, with the acrophase located on 2 August. There was a significantly higher incidence of idiopathic priapism between April and September.

Adolescent↗
PubMed1989

The loss of circadian rhythmicity of urinary solute excretion in idiopathic stone formers.

Circadian rhythmicity in urinary volume and excretion of creatinine, calcium, oxalate, uric acid and phosphate was studied in 15 idiopathic stone formers and in 17 control subjects who were age-matched, related adult males, living in the same house and engaged in similar occupations to those of the stone patients, but who had no clinically obvious stone disease. Three-hourly urine samples were collected and creatinine, calcium, oxalate, uric acid and inorganic phosphate were estimated. The time series of data were analysed by cosinor rhythmometry. Circadian rhythmicity has been described in urinary volume and urinary excretion of creatinine, calcium, oxalate, uric acid and inorganic phosphate in normal subjects, but it was not detected in the stone formers. The control subjects exhibited a circadian rhythmicity only in urinary volume and creatinine excretion. Thus they occupied a position midway between healthy adults, who exhibit circadian rhythmicity in all of the above parameters, and the stone formers, who appear to have lost it altogether.

Adult↗
PubMed1989

Comparative study of the circadian rhythmicity in the urinary concentration of glycosaminoglycans in patients of calcium oxalate nephrolithiasis and in healthy adults.

Glycosaminoglycans (GAGs) are potent inhibitors of calcium oxalate crystallisation and/or crystal aggregation. Urinary concentration of GAGs has been shown to vary during 24 h; therefore, circadian rhythmicity in urinary concentration of GAGs was investigated in 33 healthy male adults in the age group of 20-40 years and in 27 male patients of a similar age group with calcium nephrolithiasis. Three-hourly urine samples were collected for 24 h beginning from 00.00 h for estimation of urinary concentration of GAGs. The data of each patient was analysed by single cosinor rhythmometry and population mean-cosinor rhythmometry was then applied to each group. Twenty-four-hour urinary excretion of GAGs was significantly less in renal calculus patients (16.867 +/- 5.89 mumol) than in healthy subjects (22.588 +/- 5.32 mumol; p less than 0.001). A statistically validated circadian rhythm in urinary concentration of GAGs was demonstrated in both the groups. However, the amplitude-acrophase test revealed a significant difference between the two groups (F2,57 = 8.305; p less than 0.001); the amplitude was 2.354 mumol/l in patients with nephrolithiasis, whereas the amplitude was 7.028 mumol/l in healthy adults. The mesor test also revealed a significant difference in the 3-hour urinary concentration of GAGs between the two groups (18.536 mumol/l in healthy adults vs. 9.728 mumol/l in patients with nephrolithiasis). Thus in patients with nephrolithiasis, not only is the 24-hour urinary excretion of GAGs significantly low but the 3-hourly urinary concentration of GAGs is also significantly decreased as compared to healthy subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗