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Biomedical subjects

G Menon

Publications and source records attributed to G Menon.

At least 37 records · Page 2Linked to original sources
PubMed1997

Morphology of lipid alterations in the epidermis: a review.

An overview of the morphological correlates of mammalian epidermal lipids and the cutaneous permeability barrier is provided. The following features are discussed: 1) ultrastructural characterization of the progressive lipid alterations accompanying normal stratum corneum (SC) formation; 2) effects of drugs/inhibitors that interfere with specific aspects of epidermal lipid metabolism; 3) lipid alterations in certain human skin disorders; 4) effects of selected topical emollients on SC lipid organization; and 5) potential pitfalls in interpretation of ultrastructural data in terms of cutaneous function and dysfunction.

Administration, Cutaneous↗
PubMed1997

Surgery in primary supratentorial intracerebral hematoma: a meta-analysis of randomized trials.

OBJECTIVES: To examine through a meta-analysis whether a treatment strategy of surgery plus the routine medical management saves lives and reduces disability in survivors of primary supratentorial intracerebral hematoma compared to routine medical management alone. MATERIAL AND METHODS: Computerized bibliographic search of published research, conference proceedings, monographs and experts yielded 373 articles, of which only four were randomized trials. The methodological quality of the trials was assessed by two observers (weighted kappa = 0.8). Two independent reviewers abstracted the data on patient sample, type of surgery and outcomes in terms of death and dependence versus independence. Based on the nature of the intervention and the results of test for homogeneity, we analyzed the results of craniotomy and endoscopic evacuation separately. RESULTS: Review of the three trials of craniotomy suggests that it increases the risk of death or dependence (pooled risk difference 13%, 95% CI 3% to 23%), though the study with the largest sample size was conducted in the pre-CT period. Reanalysis of the endoscopic evacuation trial data showed decrease in risk of death or dependence (risk difference -18%, 95% CI -36% to 0%), the effect being similar across the different subgroups of patients according to the site of hematoma, but probably larger in patients aged less than 60 years or hematoma size of more than 50 cc. CONCLUSIONS: The role of craniotomy and stereotactic surgery has not been adequately studied in randomized trials. The results of a single trial suggest that endoscopic evacuation is a promising form of treatment in patients with primary supratentorial intracerebral hematoma, but this finding needs confirmation in a larger trial.

Activities of Daily Living↗
PubMed1994

A portable dual energy x-ray absorptiometry technique for the measurement of bone mineral in preterm infants.

A dual energy x-ray absorptiometry technique has been developed for the measurement of bone mineral in preterm infants. Two films are taken of the infant's forearm using a standard mobile x-ray set on the ward at two x-ray energies. Included in the field of view is a double step wedge made of aluminum and Perspex. The images are digitized by viewing them on a light box with a TV camera. The bone mineral content in the forearm can then be mapped by the measurement of light intensity in matching pixels of the two films and comparison with the intensities in the step wedge. The bone mineral concentration in the radius, expressed as bone mineral per unit length (mg/mm), is calculated. The technique has been tested using phantoms of calcium hydroxylapatite set in a tissue equivalent material and in Perspex. It has been shown that the reproducibility of the technique is approximately 7% and that there is a systematic underestimate of bone mineral of about 17%. The technique has been shown to be linear up to a bone mineral concentration of 8 mg.mm-1. Longitudinal studies for 14 infants that show an initial 6-wk period of demineralization after birth with a subsequent mineralization phase are reported.

Absorptiometry, Photon↗
PubMed1993

Anaesthetic implications of the anti-cardiolipin antibody syndrome.

The anti-cardiolipin antibody syndrome (or anti-phospholipid antibody syndrome) is characterized by the presence of autoantibodies to phospholipids. Its major association is with systemic lupus erythematosus. It is characterized further by in vitro prolongation of phospholipid-dependent coagulation tests. However, in vivo it is associated with a markedly increased incidence of thrombosis, both arterial and venous. We describe the case of a 36-yr-old female patient with the anti-cardiolipin antibody syndrome who presented initially for diagnostic laparoscopy and later for exploratory laparotomy. Her postoperative course after the first general anaesthetic was complicated by disseminated intravascular coagulation and adult respiratory distress syndrome. After the second operation, she deteriorated further with worsening cardiac, renal and respiratory function and eventually died. As far as we are aware, this is the first reported case of the anti-cardiolipin antibody syndrome in anaesthetic literature. Further aspects of this puzzling condition and its anaesthetic implications are discussed.

Adult↗
PubMed1993

Epidermal water permeation in vertebrates: an in vitro study using tritiated water.

Structural lipids play an important role in the water holding property of the skin. beta emitters are known to pass through the skin barrier. A permeability cell was constructed and tritiated water was used to determine the rate of in vitro water permeation through the epidermis. The epidermal sheets from different classes of vertebrates were compared for water permeation. Some of the samples were treated with solvents, surfactants and conditioners, to fathom permeability changes of the epidermis after these treatments, at various time intervals. Solvent treated epidermal sheets show very high degree of permeation, both in rat pup skin and pigeon skin. Glycerol, Brij 99 and beewax treated skin shows negligible permeation; or rather, helps in retention of water compared to normal and solvent treated skin. Comparison of water permeation in rat, pigeon and lizard skin shows that the reptilian integument is more efficient, as it allows very less permeation of water compared to the avian and mammalian epidermis. These observations suggest that tritiated water could be used for determining in vitro water permeation through the epidermis.

Animals↗
PubMed1992

Characterization of the molecular species of glycerophospholipids from rabbit kidney: an alternative approach to the determination of the fatty acyl chain position by negative ion fast atom bombardment combined with mass-analysed ion kinetic energy analysis.

An alternative approach to identifying fatty acid chain position in the molecular species of glycerophospholipids has been studied and developed. The fatty acyl groups esterified to the glycerol backbone in isomeric glycerophosphatidyl-choline, -serine and -ethanolamine as well as glycerophosphatidic acid can be detected by the presence of a pair of anions derived from phosphatidic acid parent ions (M minus the polar head groups in glycerophospholipids), designed to be [M--polar head--R2COOH]- and [M--polar head--R2CO--H]-, produced by negative ion fast atom bombardment combined with mass-analysed ion kinetic energy analysis. Because of the significant abundance of [M--polar head--R2COOH]- anion, fatty acid chains differing by 2 Da can be distinguished by accurate measurements of the electrostatic voltage related to this ion. Three-volt differences can be evidenced. Using this approach, the molecular species of glycerophosphatidyl-choline, -serine, -ethanolamine and -inositol from rabbit kidney were characterized after the separation of both class and species by normal and reversed-phase high-performance liquid chromatography, respectively. We identified 11 arachidonoyl-containing molecular species of glycerophospholipids and the other 17 lipid molecules in this biological material. A couple of 1- alkenyl-2-arachidonoyl-sn-glycerol-3-phosphoethanolamine species, identified as plasmalogen GPE 16:0-20:4 and plasmalogen GPE 18:0-20:4, were found for the first time in rabbit kidney.

Animals↗
PubMed1991

Characterization of a posttranslational fucosylation in the growth factor domain of urinary plasminogen activator.

A posttranslational modification site in natural and recombinant urinary-type plasminogen activators (urokinases; EC 3.4.21.31) has been localized to Thr-18, in the growth factor domain of the molecule. This is the region of urinary plasminogen activator responsible for its specific receptor binding. An unusual carbohydrate-protein linkage, a single monosaccharide, fucose, covalently attached directly to threonine in the peptide, is described here. The glycan moiety and the site of modification have been identified with mass spectrometry and confirmed by carbohydrate composition analysis, Edman degradation, and one- and two-dimensional NMR studies. This type of modification is normally not detected without mass spectrometry because the fucose-threonine bond is hydrolyzed under standard acidic conditions of the amino acid analysis and Edman sequencing. This modification may be widely found in other proteins.

Amino Acid Sequence↗
PubMed1991

Midtrimester termination of pregnancy--search for a better method continues.

Every day a new method of termination of second trimester pregnancy clearly indicates that we have still not found a simple, safe, effective and economic method of termination of pregnancy in second trimester. Present study of 855 cases aims at searching out something better from available modalities. Age old hypertonic saline and ethacridine lactate were used with adjuvants like hyaluronidase and a preparation containing isapgol husk to reduce injection abortion interval and failures. Life threatening dangers of hypertonic saline are known. Ethacridine lactate seems to be safe. By giving it intra-amniotically with these adjuvants its major disadvantages could be minimised. There was no mortality. However, there was morbidity in the series.

Abortifacient Agents↗
PubMed1990

Carbohydrate composition and presence of a fucose-protein linkage in recombinant human pro-urokinase.

A new post-translational modification site in the growth factor domain of urinary type plasminogen activator has been identified. A glycopeptide containing the monosaccharide, fucose, covalently linked directly to the peptide backbone has been isolated from the tryptic digest of pro-urokinase expressed in a mouse hybridoma cell line Sp 2/0 Ag 14. The glycopeptide was isolated by semi-preparative reversed phase high performance liquid chromatography. The identity of a fucose containing peptide was confirmed by carbohydrate analysis, amino acid analysis and plasma desorption mass spectrometry (PDMS). A combination of these methodologies showed an equimolar ratio of peptide and fucose in the glycopeptide. This modification is not detected without mass spectrometry because the fucose residue is hydrolyzed under standard acidic conditions of amino acid composition and N-terminal sequence analysis. The site of attachment of fucose to the peptide has been localized towards the N-terminus (within first 23 amino acids) of the protein. Also, the carbohydrate composition of recombinant pro-urokinase is reported.

Amino Acid Sequence↗
PubMed1989

Determination of phosphatidylcholine and disaturated phosphatidylcholine content in lung surfactant by high performance liquid chromatography.

A rapid isocratic method for determining the total phosphatidylcholine and disaturated phosphatidylcholine levels in lung surfactant preparations by high performance liquid chromatography (HPLC) is described. The analysis was performed on a 3.9 x 300 mm mu-Porasil column with detection by refractive index. The lipids were eluted with a solvent system of chloroform-acetonitrile-methanol-water-85% phosphoric acid 650:650:500:130:2 (v/v/v/v/v). A 4.6 x 30 mm silica guard column was used in place of an injector loop which served as a sample concentrator and purifier. Phosphatidylinositol, phosphatidylserine, phosphatidylethanolamine, and phosphatidylglycerol, all known components of lung surfactants, were eluted from the loop column and were prevented from reaching the analytical column. Sphingomyelin and lysophosphatidylcholine elute later than the phosphatidylcholines on the analytical column. The method was developed so that phosphatidylcholines elute as a single peak regardless of the fatty acid chain length (C12-C20). When the sample was first oxidized with a potassium permanganate-potassium metaperiodate solution, and potentially interfering oxidation products were removed by extraction into a basic aqueous phase, then only the disaturated phosphatidylcholines were analyzed.

Animals↗
PubMed1988

Life prolongation: views of elderly outpatients and health care professionals.

A peculiar dynamic in communication exists between those who are most likely to be involved in life-prolongation decisions. We found that both the elderly and health care professionals talk about life-prolongation, but not with one another; that they consider some of the same factors as they think about the life-prolongation decision; and that most of them believe physicians should be responsible for initiating discussion. However, the physician or health care professional who wishes to avoid crisis situations also is reluctant to broach the issue for fear of unnecessarily alarming or compromising the defense mechanisms of the patient. The patient remains patient, waiting--with fears of dependency, memories of previous life-threatening experiences, and deep sensitivity for suffering--for the physician to initiate the discussion. Is a mediator such as a family member necessary in these situations? Is the hospital environment not conductive to discussion of less than heroic efforts?

Age Factors↗
PubMed1985

Why does congenital heart disease cause failure to thrive?

Metabolisable energy intake, determined by bomb calorimetry of food, vomit, stool and urine, and resting metabolism, assessed by respiratory gas exchange, were studied in 21 infants with congenital heart disease and nine control infants. Weight for age, growth rates, and daily metabolisable energy intake per kg tended to be lower in infants with heart disease than in control infants. Resting oxygen consumption was high in those infants with pulmonary hypertension and persistent cardiac failure. Energy intake, as a percentage of that recommended for age, correlated with weight gain, and resting oxygen consumption correlated inversely with both percentage body mass index and relative fatness. Failure to thrive in infants with congenital heart disease may be due to a combination of low energy intakes and, in some cases, high energy requirements allowing insufficient energy for normal growth. Increasing the energy intakes of infants with congenital heart disease may be a way of improving their growth.

Body Weight↗
PubMed1984

Simultaneous determination of chloroprocaine hydrochloride and its degradation product 4-amino-2-chlorobenzoic acid in bulk drug and injection solutions by high-performance liquid chromatography.

A high-performance liquid chromatographic method has been developed for the simultaneous determination of chloroprocaine hydrochloride and its hydrolytic degradation product, 4-amino-2-chlorobenzoic acid. Separation is achieved using a mu-Bondapak C18 column and the eluant, water-acetonitrile-methanol-glacial acetic acid (74:20:5:1) containing 0.05-0.08% (w/v) sodium 1-heptanesulfonate, at a flow rate of 2 mL/min. Benzoic acid and p-nitroacetophenone were used as internal standards. A variable-wavelength UV detector (278 nm) was used for detection of the compounds. The method is simple, accurate, and precise.

Chromatography, High Pressure Liquid↗