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Biomedical subjects

R N Roy

Publications and source records attributed to R N Roy.

At least 19 recordsLinked to original sources
PubMed1992

Expression of natriuretic peptide genes in cardiac tissues of hypertensive rats.

A quantitative assay using a reverse transcriptase-linked polymerase chain reaction has been developed for measuring the levels of rANP and iso-rANP mRNA. A linear correlation between total RNA template and amplified cDNA was obtained for the amplification of cDNA from both iso-rANP and rANP mRNAs even when both cDNAs were amplified in the same assay. Application of the assay showed that in contrast to rANP levels of iso-rANP transcript in hypertensive rats remained approximately the same in atrium but were increased 10-fold in ventricle compared to normal rats. Given the relative size of the ventricle the increase of iso-rANP in this tissue in SHR may be a major response to the hypertensive state.

Animals↗
PubMed1992

Crohn's disease & aflatoxins.

An investigation to examine the relationship between Crohn's disease and aflatoxins, a group of structurally related toxic and carcinogenic metabolites, was carried out on 24 patients. Extracts of serum and urine from the patients were assayed qualitatively by thin layer chromatography and the Aflatest method, and quantitatively by fluorimetry. There was evidence that some patients suffering from Crohn's Disease, together with some having coeliac disease and ulcerative colitis, did have varying amounts of aflatoxins in their serum and urine. The presence of aflatoxins may have been due to exposure to food containing these toxins or inability of the patient to excrete aflatoxins on account of some gastro-intestinal derangement. Only long-term investigation would establish the link between dietary history and the presence of aflatoxins in these patients.

Aflatoxins↗
PubMed1990

Organization of the gene for iso-rANP, a rat B-type natriuretic peptide.

Using the polymerase chain reaction and oligonucleotide primers constructed from knowledge of the cDNA sequence we have sequenced the gene for iso-rANP, a peptide of the B-type of atrial natriuretic peptides. The overall organization of the rat iso-ANP gene is the same as that of ANP and BNP consisting of three exons and two introns at relatively similar positions. Iso-rANP and it's gene are more closely related to BNPs than ANP and yet there are significant differences at both the protein and DNA levels. Our results suggest that iso-rANP and BNP are distinct members of the same sub-family (B-type natriuretic peptides) within the family of natriuretic peptide genes.

Amino Acid Sequence↗
PubMed1990

Methods of delivery and resuscitation of very-low-birthweight infants in Victoria: 1982-1985.

This article describes the patterns of delivery and resuscitation for very-low-birthweight infants who were born in Victoria from 1982 to 1985. Caesarean delivery rates increased from 15% to 30% for infants of birthweights of 500-999 g, and from 39% to 52% for infants of birthweights of 1000-1499 g. In level-III hospitals, the proportion of live-born infants who did not receive active resuscitation fell from 32% to 18% for those who weighed 500-999 g, and from 28% to 15% for those who weighed 1000-1499 g. Time trends over the four years showed the management of very-low-birthweight infants to be in a state of rapid transition in all birth settings. At the same time there was a fall in the still-birth rate of infants of birthweights of 500-999 g. Still-births rates for infants of birthweights of 1000-1499 g remained unchanged, as did neonatal mortality rates in both weight groups.

Apgar Score↗
PubMed1990

Developmental regulation of specific protein interactions with an enhancerlike binding site far upstream from the avian very-low-density apolipoprotein II gene.

Expression of the avian very-low-density apolipoprotein II (apoVLDLII) gene is completely dependent on estrogen and restricted to the liver. We have identified binding sites for nonhistone nuclear proteins located between -1.96 and -2.61 kilobases. One of these sites, located at -2.6 kilobases (designated site 1), was found to span an MspI site that becomes demethylated between days 7 and 9 of embryogenesis, the stage of development at which competence to express the apoVLDLII gene begins to be acquired. Levels of the factor(s) involved were high at day 7 of embryogenesis, decreased two- to threefold by days 9 to 11, and continued to decline more slowly until hatching. Furthermore, the mobility of the complex formed underwent a well-defined shift between days 11 to 13 embryogenesis. Methylation interference studies showed that modification of the outer guanosines of the MspI site resulted in marked inhibition of the formation of the protein-DNA complex. Competition studies, fractionation of nuclear extracts, and tissue distribution indicated that the factor was not the avian homolog of hepatocyte nuclear factor 1, nuclear factor 1, or CCAAT/enhancer-binding protein (C/EBP). However, site 1 could complete for binding to an oligonucleotide, previously shown to be recognized by C/EBP, in a nonreciprocal fashion. These studies demonstrate that the sequence recognized by the protein includes a C/EBP consensus sequence but that elements in addition to the core enhancer motif are essential for binding.

Age Factors↗
PubMed1990

The Melbourne Chart--a logical guide to neonatal resuscitation.

Resuscitation of the asphyxiated infant is one of the great emergencies in medical practice. Properly done, it can save many lives and greatly reduce the morbidity resulting from hypoxic-ischaemic encephalopathy, but if it is ineptly performed, the effects of hypoxic-ischaemic encephalopathy may be accentuated, with resultant increased morbidity and even mortality. Other than paediatricians, few practitioners have regular experience in neonatal resuscitation: indeed many, including obstetricians, anaesthetists, general practitioners and midwives may only rarely face the problem of severe asphyxia. It is therefore essential for the occasional practitioner to have ready reference to a logical guide to resuscitation. We have designed such a guide which is widely distributed in delivery suites and operating theatres in Victoria. Its basic form has been in use for over a decade and it has recently been revised. Use of the chart assists the resuscitator to judge the level of resuscitation required. It is our experience that much unnecessary intervention occurs at resuscitation, and we believe the methods outlined in this schematic chart represent a more conservative but logical approach to neonatal resuscitation. The chart is based on the pathophysiological changes that occur in perinatal asphyxia, directing the user to the appropriate manoeuvres required to correct those changes, depending on the degree of asphyxia which is determined by clinical signs and by use of the Apgar score.

Apgar Score↗
PubMed1989

Observations on spinal dysraphism.

An attempt has been made to look into the age at presentation, incidence and clinical presentation of 40 patients with spinal dysraphism. Thirteen cases of myelomeningocele and 11 cases of meningocele constituted the 'aperta' group and there were 16 'occulta' cases. Though among the 'aperta' cases male is to female ratio was 1:1, a marked male preponderance of 2.2:1 was seen among 'occulta' cases. First born child was found to be most frequently (44.50%) affected in the present series. Myelography remained a mainstay in deciding operation in 'occulta' cases. All 'aperta' cases and 11 out of 16 'occulta' cases were treated by operation. Regarding results of treatment, all cases with meningocele were fully cured, cases with myelomeningocele showed no improvement but further deterioration of the neurological status could be arrested. Hydrocephalus was associated in 8 out of 13 cases with myelomeningocele and ventriculoperitoneal (VP) shunt were instituted in all of them. Prognostic significance of presence of hydrocephalus was profoundly grave as was evident from the mortality rate (10%) in this series.

Adolescent↗
PubMed1988

Increased mortality of preterm infants transferred between tertiary perinatal centres.

Over 18 months almost one quarter of infants born before 30 weeks' gestation in a tertiary perinatal centre who required intensive care had to be transferred to other tertiary centres because intensive care facilities were fully occupied. When infants with lethal congenital malformations were excluded half of the 34 infants who were transferred died; this was twice the mortality (24%) in the 111 infants remaining. The difference between the groups was significant (relative odds = 3.1) and remained so after adjustment for any discrepancies in gestational age (relative odds = 4.0). After adjustment for potential confounding variables by logistic function regression the risk of dying for those transferred remained significantly higher than that for infants who remained (relative odds = 4.6, 95% confidence interval 1.8 to 12.1). As the requirement for neonatal intensive care is episodic and unpredictable more flexibility has to be built into the perinatal health care system to enable preterm infants delivered in tertiary perinatal centres to be cared for where they are born.

Australia↗
PubMed1988

The survival of extremely-low-birthweight infants in Victoria: 1982-1985.

A population-based survey of mortality in extremely-low-birthweight (500- to 999-g) infants was carried out in Victoria for the years 1982 to 1985. No increase in the number of extremely-preterm births occurred during that time. The still-birth rate fell from 498 still births per 1000 births in 1982-1983 to 403 still births per 1000 births in 1984-1985. The neonatal mortality in 1982-1985 was 638 deaths per 1000 live births, with no significant decline from that of the 1978-1981 cohort. The small increase in neonatal survivors was not associated with any change in the postneonatal death rate. Delivery in a level-3 unit was associated with a significantly better outcome. Multiple births made a major contribution to the extremely-low-birthweight group of infants.

Birth Weight↗
PubMed1988

A novel insertion sequence in the cryptic plasmid of Neisseria gonorrhoeae may alter the B protein at the translational level.

A variant of the cryptic plasmid of Neisseria gonorrhoeae, 4.4 kb in size, was isolated and characterized at the molecular level. This variant harbored a 156-bp insertion which was located between coordinates 3134 and 3135 within the putative cppB gene using the 4.2-kb cryptic plasmid, pJD1, as a reference. The insertion contained a novel EcoRI site and several elements of symmetry (both direct and inverted repeats). Stop codons present in the insertion interrupted the coding capacity of the cppB gene. Although the insertion was within one of two previously characterized 44-bp repeats purportedly involved in site-specific recombination, it was distinct from a 54-bp segment deleted in some cryptic plasmids. The presence of the insertion suggests a mechanism of modulating the expression of the cppB gene at the translational level through DNA rearrangement.

Amino Acid Sequence↗
PubMed1987

Cranial ultrasound screening of preterm and term neonates.

A cranial ultrasound examination was performed between 48 and 96 h of age on 580 neonates of 25-42 weeks gestation. The incidence of cerebroventricular haemorrhage (CVH) in infants less than 32 weeks gestation was 37%, compared with an incidence of 2.7% in infants of 32 weeks or more. The incidence of CVH unselected healthy term infants (between 37 and 42 weeks) was only 1.1%. Of the 13 infants of 32 weeks or more who were found to have a haemorrhage, nine had a small (Grade I) haemorrhage (69%) and none of these infants had abnormal neurological signs in the neonatal period. The remaining four infants with Grade II, III or IV haemorrhage developed either seizures or episodes of apnoea. Two of the 13 infants of 32 weeks or more with a haemorrhage died, one during the newborn period and the other at 5.5 months of age. CVH in asymptomatic infants of 32 weeks or more gestation is uncommon and does not justify routine cranial ultrasound scanning.

Cerebral Hemorrhage↗
PubMed1985

Standard electromotive force of the H2-AgCl;Ag cell in 30, 40, and 50 mass% glycerol/water from -20 to 25 degrees C: pK2 and pH values for a standard "mops" buffer in 50 mass% glycerol/water.

Data are presented regarding the establishment of the pH (designated pH*) of a standard buffer solution suitable as a pH reference in 50 mass% glycerol/water mixtures at temperatures ranging from -20 to 25 degrees C. The buffer material selected was the ampholyte Mops [(3-N-morpholino)-propane sulfonic acid], and the reference standard consists of equal molal amounts of Mops and its sodium salt. The assignment of pH* values is based on measurements of the electromotive force (emf) of cells without liquid junction of the type: Pt;H2(g, 1 atm) / Mops, Na Mopsate, NaCl / AgCl;Ag and the pH* was derived from a determination of K2, the equilibrium constant for the dissociation process (Mops) +/- in equilibrium with (Mopsate)- + H+. The standard emf of the silver-silver chloride electrode in 30, 40, and 50 mass% glycerol/water mixtures was determined from emf measurements of the cell at subzero temperatures with HCl solutions replacing the buffer-chloride mixtures.

Buffers↗
PubMed1985

Acid dissociation constants and pH values for standard "bes" and "tricine" buffer solutions in 30, 40, and 50 mass% dimethyl sulfoxide/water between 25 and -25 degrees C.

Information is given concerning two standard buffer solutions suitable as pH references in 30, 40, and 50 mass% dimethyl sulfoxide (DMSO)/H2O mixed solvents at subzero temperatures from -20 to 0 degrees C, with the intention of establishing a pH (designated pH*) scale. The two buffers selected were the ampholytes N,N-bis(2-hydroxyethyl)-2-aminoethane sulfonic acid ("bes") and N-tris(hydroxymethyl)methylglycine ("tricine"), and the reference standard consisted of equal molal quantities of the buffer and its respective sodium salt. The assignment of pH* values was based on measurements of the emf of cells without liquid junction of the type: Pt;H2(g,l atm) /Bes, Na Besate, NaCl / AgCl;Ag and Pt;H2(g,l atm) /Tricine, Na Tricinate, NaCl /AgCl;Ag and the pH* was derived from a determination of K2, the equilibrium constant for the dissociation process (Buffer)+/- in equilibrium with(Buffer)- + H+.

Alkanesulfonates↗
PubMed1985

Perinatal factors, periventricular haemorrhage and mortality in very low birthweight infants.

In a population of 225 very low birthweight infants born over a 21 month period the cerebroventricular system was scanned by ultrasound. One third of the infants developed a periventricular haemorrhage; in 41% of infants the haemorrhage was detected before an hour of age and 66% of all haemorrhages occurred within the first 24 hours. Statistically significant associations with periventricular haemorrhage included vaginal delivery, endotracheal intubation and intravenous sodium bicarbonate when this was administered in the first 24 hours. In a stepwise regression analysis, however, these and other potentially significant variables added little to the total accountable variance. A similar analysis of perinatal factors and mortality revealed that decreasing gestation was the major association with death.

Bicarbonates↗
PubMed1985

Ventricular size in newborn infants.

Cranial ultrasound examinations were performed on 533 infants of between 48 and 96 hours of age to establish the range of ventricular size in neonates of different gestational ages in whom there was no evidence of intraventricular hemorrhage or neural tube defects. It was found that ventricular size did not vary in infants with gestational age of 26 weeks or more. Only 15 (2.8 per cent) neonates had a ventricular width of greater than 3 mm. Of these 15 infants, 13 were re-examined within the first year of life and found to be neurologically and developmentally normal.

Anthropometry↗