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Biomedical subjects

D Savva

Publications and source records attributed to D Savva.

At least 19 recordsLinked to original sources
PubMed1998

Genetic variation in human serum albumin: a 313 Lys-->Asn mutation in albumin reading identified by PCR analysis.

An early case of bisalbuminaemia was reported in this journal in 1964, with the name Albumin Reading added later. Its use in electrophoretic comparisons led to some new variants being described as 'of the Reading type' on this basis alone. Protein sequencing and DNA studies have since found the single point mutation 313 Lys-->Asn common to this type, but the eponymous variant has not, until recently, been available for study. We now report on its characterisation using PCR analysis with allele-specific oligonucleotide primers, a method also applicable to studies of the population distribution of variants. We also draw attention to the need to link clinically-significant effects to individual variants of known structure.

Aged↗
PubMed1998

Use of DNA fingerprinting to detect genotoxic effects.

The effects of environmental pollutants on organisms may be monitored in a number of ways and at different levels. In the case of genotoxic chemicals, the effects on the DNA may be monitored using a number of biomarker assays capable of detecting phenotypic changes as a result of mutation, gross chromosomal abnormalities, unscheduled DNA synthesis, DNA adducts (e.g., by 32P postlabeling or by ELISA) and DNA strand breaks (e.g., by the alkaline unwinding assay or the comet assay); the sensitivity and specificity of these assays are variable. Recent developments in molecular biology such as DNA fingerprinting and gene amplification by the polymerase chain reaction (PCR) offer new possibilities for detecting DNA damage. In this laboratory, whether an alternative biomarker assay (using DNA fingerprinting by arbitrarily primed PCR) can reveal differences in the DNA fingerprints of individuals from control and polluted areas was investigated. The results indicate that DNA fingerprinting by arbitrarily primed PCR offers a useful alternative biomarker assay for detection of the genotoxic effects of environmental pollutants.

Animals↗
PubMed1997

Attenuation of the haemodynamic responses to noxious stimuli in patients undergoing cataract surgery. A comparison of magnesium sulphate, esmolol, lignocaine, nitroglycerine and placebo given i.v. with induction of anaesthesia.

A study was conducted on 100 middle-aged to elderly patients (n = 52, healthy; n = 48, suffering from either diabetes, hypertension, ischaemic heart disease or a combination of these diseases) undergoing cataract extraction to assess the effects of laryngoscopy and tracheal intubation, anaesthesia and surgery, eye bandaging and tracheal extubation, saline (control), magnesium sulphate 40 mg kg-1, esmolol 4.0 mg kg-1, lignocaine 1.5 mg kg-1 and glyceryl trinitrate 7.5 micrograms kg-1 given i.v. at induction of anaesthesia on heart rate (HR), blood pressure (BP), rate-pressure product (RPP) and pressure-rate quotient (PRQ). Anaesthesia was standardized. Haemodynamic responses and requirements for atropine, ephedrine and labetalol to maintain HR and BP during surgery were similar in healthy and diseased patients, and in the test drug groups. Differences produced by the test drugs were evident until 5 min following intubation. Esmolol prevented rises in HR and RPP. Glyceryl trinitrate prevented a rise in BP, but was associated with tachycardia and a fall in PRQ to < 1.0. Magnesium sulphate and lignocaine did not prevent responses to laryngoscopy and tracheal intubation, and were associated with rises in RPP. Application of the eye dressing and tracheal extubation at the end of surgery each caused significant increases in HR, BP and RPP in all groups.

Adrenergic beta-Antagonists↗
PubMed1996

Molecular cloning of a lytic beta-1,3-glucanase gene from Oerskovia xanthineolytica LLG109. A beta-1,3-glucanase able to selectively permeabilize the yeast cell wall.

Molecular cloning of the beta gIII gene encoding for an endo-beta-1,3-glucanase (beta gl II) from Oerskovia xanthineolytica LLG109, a yeast-lytic gram-positive bacterium, has been conducted in order to elucidate its primary sequence and subsequently express it into B. subtilis. This endo-beta-1,3-glucanase exhibits low yeast-lytic activity toward viable S. cerevisiae cells, and it has shown ability to selectively permeabilize the yeast cell wall and release intracellular proteins produced by yeast. Highly degenerate oligonucleotides have been used to PCR-amplify a region of the beta-1,3-glucanase II encoding gene from O. xanthineolytica LLG109. The amplified fragment has been cloned and sequenced. The deduced amino acid sequence contains regions identical to the amino acid sequences previously determined by direct sequencing of the purified enzyme from O. xanthineolytica LLG109. By using the 180-bp PCR product as a homologous probe, we have been able to isolate four positive clones harboring plasmids pPF1A, pPF1B, pPF8A, and pPF9A, respectively, from a partial genomic library from O. xanthineolytica LLG109. All four plasmids contained a 2.7-kb BamHI insert that hybridized to the PCR probe under high stringency conditions. The 2.7-kb fragment seemed to be identical in all four cases regarding preliminary partial restriction mapping analysis done on the four plasmids. The 1.5-kb BamHI/KpnI restriction fragment from pPF8A and pPF9A hybridizing with the 180-bp PCR probe is presently being sequenced. The cloning of the lytic beta-1,3-glucanase from O. xanthineolytica LLG109 expands the number of yeast lytic beta-glucanases so far cloned. The availability of the nucleotide sequences of such a family of genes will allow further understanding of the role and mode of action of these enzymes in yeast cell wall degradation. In addition, a more extensive study on the structure and functional relationships of these enzymes will allow us to engineer "tailor-made" lytic beta-1,3-glucanases for use in new and improved large-scale selective cell permeabilization (SCP) and selective protein recovery (SPR) from yeast cells, not only from S. cerevisiae but also from alternative yeast expression systems such as Hansenula polymorpha, Pichia pastoris, and others, which are becoming of increasing importance in biotechnology.

Amino Acid Sequence↗
PubMed1996

Pro-opiomelanocortin and adrenal function.

Pro-opiomelanocortin (POMC) is a polyhormone precursor produced predominantly in the pars distalis and pars intermedia of the pituitary gland where it undergoes tissue specific processing to produce a whole array of peptides. We have shown previously that peptides derived from the N-terminal region of POMC are involved in adrenal growth in rats. Using specific two site immunoradiometric assays we have found that the plasma of 17 week old fetal sheep contain a 50 fold excess of pro-gamma-MSH over ACTH. As term approached, the levels of pro-gamma-MSH fell and ACTH rose with evidence of fragmentation of pro-gamma-MSH, suggesting that these peptides act in concert in the development of the fetal adrenal cortex and also provide the necessary drive to bring about parturition. In an attempt to explore the pathophysiology of adrenal function we have cloned human POMC cDNA which led to the discovery of a 9bp addition/deletion mutation in the C-terminus of gamma 3-MSH between positions 67-73. Chinese hamster ovary cells (CHO) cells stably transfected with constructs containing the variant POMC cDNAs have shown a degree of partial processing. Work is currently underway to further investigate the effects of these mutations on the processing by the prohormone converting enzymes PC1 and PC2.

Adrenal Glands↗
PubMed1996

Nucleotide sequence of a beta-1,3-glucanase isoenzyme IIA gene of Oerskovia xanthineolytica LL G109 (Cellulomonas cellulans) and initial characterization of the recombinant enzyme expressed in Bacillus subtilis.

The nucleotide sequence of the betaglIIA gene, encoding the extracellular beta-1,3-glucanase IIA (betaglIIA) of the yeast-lytic actinomycete Oerskovia xanthineolytica LL G109, was determined. Sequence comparison shows that the betaglIIA enzyme has over 80% identity to the betaglII isoenzyme, an endo-beta-1,3-glucanase having low yeast-lytic activity secreted by the same bacterium. The betaglIIA enzyme lacks a glucan- or mannan-binding domain, such as those observed in beta-1,3-glucanases and proteases having high yeast/fungus-lytic activity. It can be included in the glycosyl hydrolase family 16. Gene fusion expression in Bacillus subtilis DN1885 followed by preliminary characterization of the recombinant gene product indicates that betaglIIA has a pI of 3.8 to 4.0 and is active on both laminarin and curdlan, having an acid optimum pH activity (ca. 4.0).

Actinomycetales↗
PubMed1995

Comparison of total intravenous, balanced inhalational and combined intravenous-inhalational anaesthesia for tympanoplasty, septorhinoplasty and adenotonsillectomy.

Two hundred and thirty-five consecutive Saudi patients aged between two and fifty-three years undergoing elective tympanoplasty (n = 32), septorhinoplasty (n = 68) or adenotonsillectomy (n = 135) were studied. They were randomized to receive either a total intravenous anaesthetic (10 ears, 23 noses, 44 throats) consisting of propofol for induction of anaesthesia followed by a propofol infusion, a combined intravenous-inhalational anaesthetic (11 ears, 22 noses, 46 throats) consisting of the above with isoflurane in oxygen-enriched air, or a balanced inhalational anaesthetic (11 ears, 23 noses, 45 throats) consisting of thiopentone for induction of anaesthesia and oxygen in nitrous oxide with isoflurane for maintenance. During tympanoplasty, all three anaesthetic techniques produced stable heart rates and arterial pressures. During septorhinoplasty, blood pressure rose in patients who received total intravenous anaesthesia, while combined and balanced techniques produced haemodynamic stability. During adenotonsillectomy, total intravenous anaesthesia produced a rise in both heart rate and blood pressure, the combined technique produced a rise in heart rate alone while balanced anaesthesia produced haemodynamic stability. Postoperatively, vomiting, pain scores and analgesic requirements were similar following all three types of anaesthetic within each surgical site subgroup. Our findings support the choice of balanced inhalational anaesthesia for all three types of ENT surgery and, where cost and facilities permit, total intravenous anaesthesia for tympanoplasty and combined intravenous-inhalational anaesthesia for septorhinoplasty.

Adenoidectomy↗
PubMed1995

Reduced expression of a naturally deleted form of human proopiomelanocortin complementary deoxyribonucleic acid after transfection into Chinese hamster ovary cells.

POMC is the precursor molecule for a number of hormones, ACTH, MSH, and beta-endorphin. The human genomic sequence has been elucidated, but to date the complete human complementary DNA (cDNA) sequence has not been published. Here we report the cloning and expression of human POMC cDNA from the anterior pituitary gland. Two forms of POMC cDNA have been identified; one sequence agrees with the cDNA sequence predicted from the published genomic sequence, and the second is a variant with a 9-base pair deletion (corresponding to the loss of three amino acids, Ser-Ser-Gly, between residues 67-73). Both POMC cDNA sequences have been expressed in Chinese hamster ovary cells. A significant difference was observed between the levels of expression in the cells and the amount secreted into the media of the two protein precursor molecules. The expression of the deleted variant in the cells was 16.4 +/- 0.9% of the level of normal POMC (P < 0.001), and in the media the deleted variant was 22.4 +/- 2.2% of the level of normal POMC (P < 0.001).

Amino Acid Sequence↗
PubMed1995

The use of lignocaine to reduce pain on i.v. injection of diluted nalbuphine.

A randomized, placebo-controlled, double-blind study was conducted on 66 healthy patients aged 10-61 years undergoing elective ear, nose and throat surgery to assess the incidence and severity of pain associated with intravenous (i.v.) injection of diluted nalbuphine HCl given during induction of general anaesthesia, and to determine the efficacy of adding lignocaine (2 mg mL-1) to nalbuphine to reduce this pain. Injection of saline produced pain of low intensity in 15% of patients and a withdrawal response in 3% of patients. Injection of nalbuphine mixed with lignocaine produced a significantly higher incidence (36%; P < 0.025) and severity (P < 0.025) of pain than saline, but a similar number of responses (6%) to pain. The diluted nalbuphine alone produced the highest incidence (61%) of pain (P < 0.01 vs. saline, P = NS vs. nalbuphine with lignocaine), which was most severe (P < 0.01 vs. saline, P < 0.025 vs. nalbuphine with lignocaine), and caused the highest number (27%) of withdrawal responses (P < 0.01 vs. saline, P < 0.025 vs. nalbuphine with lignocaine). We conclude that diluted nalbuphine 2 mg mL-1 produces pain on i.v. injection into peripheral veins, and that this can be significantly reduced by adding lignocaine 2 mg mL-1 to the solution.

Adolescent↗