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Biomedical subjects

D Charles

Publications and source records attributed to D Charles.

At least 19 recordsLinked to original sources
PubMed1992

An improved method of in vivo wound disruption and measurement.

Biomechanical studies of wound strength are important because of new investigations in growth factors, cytokines, and fetal wounds. We compared two traditional methods of wound disruption measurement with a novel computerized model designed for in vivo experiments. An Instron tensiometer (INSTS) and an air insufflated positive pressure device (AIPPD) were compared with a vacuum-controlled wound chamber device (VCWCD). The VCWCD produced vacuum at the wound site and wound disruption was monitored with two video camera/recorders. Rats were marked with a template guide for a 2.5 cm, full-thickness, abdominal incisional wound. Rats were divided into three groups and studied at 2, 7, or 14 days after wounding. The recorded images were computer digitalized to generate wound strength curves from a three-dimensional model. A comparison of the wound disruption curves demonstrated that the VCWCD was comparable to the INST or AIPPD in normal wound healing (P greater than .40). The VCWCD provided data with less standard error at 2 days after wounding (P less than 05). In separate series of experiments, VCWCD was tested in the early phases of healing and was found to be sensitive to change at intervals of 48 hr after wounding (P less than .005). The INST or AIPPD methods could not perform this task because of an unacceptable level of random error after tissue manipulation. The VCWCD system was considered superior for evaluating early wound healing because it was an in vivo method which required minimal wound manipulation.

Animals↗
PubMed1992

[Slow ventricular tachycardia caused by naftidrofuryl overdose (naftidrofuryl and ventricular tachycardia)].

Treatment with intravenous naftidrofuryl may be complicated by ventricular arrhythmias. A case of slow ventricular tachycardia occurring in a 65-year-old man with a dilated cardiomyopathy following an accidental overdose of naftidrofuryl (2 x 200 mg ampules in 250 ml of 5% glucose solution in 2 hours) prescribed for complicated arterial disease of the lower limbs is reported. This sustained ventricular tachycardia converted spontaneously after several hours. This case emphasises the risk of arrhythmogenic effects of this drug and indicates the need for careful monitoring when it is used intravenously in patients with underlying heart disease.

Aged↗
PubMed1992

Prevalence & pathogenesis of hypophosphatemia in ventilated patients.

Hypophosphatemia was found in 12 (43%) patients within 24-36 h of mechanical ventilation in a group of 28 patients in an intensive care unit. The hypophosphatemic patients had a significant lowering of renal phosphorus threshold (P = 0.005) and inappropriate phosphaturia. These abnormalities resolved once ventilation was discontinued. Serum parathyroid hormone (PTH) levels were unaltered in this group of patients suggesting that some factor other than PTH was responsible for hypophosphatemia. This study has demonstrated that abnormalities of renal phosphate handling can cause hypophosphatemia in ventilated patients.

Adolescent↗
PubMed1991

Accumulation of pepstatin in cultured endothelial cells and its effect on endothelial processing.

Aspartic acid proteases have been implicated in the processing of ET-1(1-39) to ET-1(1-21). To further understand the role of this class of enzymes in ET-1 synthesis, cultured vascular endothelial cells were incubated with pepstatin, and the accumulation of the inhibitor and its effect on the processing of ET-1(1-39) was examined. Pepstatin accumulated in the cells in a time-dependent manner, to a concentration (greater than 10(-7) M) sufficient to inhibit aspartic acid proteases. Pepstatin did not alter the ratio of ET-1(1-21) to ET-1(1-39), nor did it affect the rate of secretion of either peptide. When endothelial cells were incubated with phosphoramidon under identical conditions, the secretion of ET-1(1-21) was significantly reduced with a concomitant increase in the secretion of ET-1(1-39). These results suggest that the processing of ET-1(1-39) does not involve a pepstatin-sensitive aspartic acid protease, and that the enzyme responsible for generating ET-1(1-21) is sensitive to phosphoramidon.

Amino Acid Sequence↗
PubMed1991

[Tumor-like focal nodular hyperplasia. Apropos of 3 cases observed at the Dakar Central Hospital from 1986 to 1989].

Authors report three observations of Focal Nodular Hyperplasia, Tumor-like on two: senegalese female patients, 16 years and 37 years old, and a young senegalese man, 24 Years old. The mean age is about 25.5 years and oestro progestative intake has bean noted once. Diagnosis of Focal Nodular Hyperplasia was difficult and has been done twice after surgical intervention for chronic cholecystitis and blood peritonitis. The only complication reported, has been a rupture of nodular, causing the death of a patient. This benign tumor that never degenerates, does not need any particular treatment unless a stopping of oral contraception.

Adolescent↗
PubMed1990

Comparisons of the clinical and radiological features and surgical management of posterior fossa meningiomas and acoustic neuromas.

Next to acoustic neuromas, meningiomas are the most common benign tumour of the posterior fossa. This paper reviews the personal experience of one of the authors with the management of 26 posterior fossa meningiomas and 212 acoustic neuromas. The aim was to compare the clinical and radiological features of these two types of posterior fossa tumours to determine whether they can be differentiated preoperatively. The study also aimed at analysing the surgical treatment of posterior fossa meningiomas. The results showed that posterior fossa meningiomas can usually be differentiated from acoustic neuromas on the basis of clinical and radiological features. Preoperative differentiation aids surgical management, especially for selection of surgical approach. In most instances, posterior fossa meningiomas can be totally resected with minimal morbidity and mortality.

Adult↗
PubMed1990

[Diagnostic suspicion. Clinical, epidemiological, radiological, and endoscopic aspects of bronchopulmonary cancer in Senegal. Apropos of 700 endoscopies performed at the Hôpital Principal de Dakar from 1987 to 1990].

700 bronchial fiber endoscopies were performed at Dakar Main Hospital over a period of 3 consecutive years. 40 broncho-pulmonary cancers were identified (34 epidermoids, 4 adeno-cancers, 2 small cell cancers) among the 80 suspect cases. Comparison of clinical, radiological and endoscopic data revealed the following information: 1. most frequently radiology showed retractile, pulmonary condensation syndrome (40 cases); 2. a large predominance of close, bulging tumours (45 times) in relation to endoscopic bronchial stenosis (22 times); 3. almost exclusive identification of bronchial epidermoid cancer in this series (34 times); 4. the masculine sex and use of tobacco remain 2 unavoidable elements in this pathology. Bronchial endoscopy, a simple, indispensible examination, allows the lesion to be visualized, and a biopsy, on its own or associated with endoscopic cysto-brushing and alveolus washing, can then furnish conclusive histological proof.

Adult↗
PubMed1989

Rat vascular tissue contains a neutral endopeptidase capable of degrading atrial natriuretic peptide.

Neutral endopeptidase (NEP, EC 3.4.24.11), purified from renal brush border, cleaves the Cys7-Phe8 amide bond of rat atrial natriuretic peptide (ANP), to generate the inactive metabolite (ANP cleaved at the Cys7-Phe8 bond; x-ANP). To determine if NEP contributes to the inactivation of circulating ANP, we investigated the degradation of rat ANP (rANP, 1-28) in the vasculature. Formation of x-ANP from exogenous ANP was studied in a mesenteric arterial preparation by perfusion in a single pass system in the presence and absence of the NEP inhibitors, thiorphan or phosphoramidon. In addition, a purified membrane fraction was prepared from mesenteric arterial homogenate and compared with an equivalent renal membrane fraction. Formation of x-ANP was quantified by a specific immunoassay (ELISA). Renal and vascular membranes shared the same pH optima for x-ANP formation (pH 7.5), although x-ANP generation was considerably greater in renal vs. vascular membranes (31.6 and 0.4 nmol min-1 mg-1 of protein, respectively). Both preparations were inhibited in a similar, dose-dependent manner by phosphoramidon, thiorphan or a polyclonal antibody to NEP. In perfused mesenteric arteries, 1.6 +/- 0.8 pmol of x-ANP were generated from 1 microgram of ANP; this formation was inhibited 51% by 10 microM phosphoramidon or thiorphan. Plasma levels of x-ANP after bolus i.v. administration of rANP in rats, were inhibited (70-80%) by thiorphan at comparable doses to those used in perfused mesenteric arteries. These studies indicate that ANP is degraded in the vasculature by NEP or an "NEP-like" enzyme(s).

Animals↗
PubMed1989

Myopic and nonmyopic aphakic retinal detachment: time interval and location of breaks.

Of 471 retinal detachments occurring in aphakic patients after undergoing intracapsular cataract extraction, we reviewed 318 eyes with uncomplicated aphakia (no vitreous loss). Myopic eyes had equatorial breaks 38% of the time versus 19% for nonmyopic eyes. The time interval between aphakia and detachment was shorter for myopic than for nonmyopic eyes. Our results showed a significant incidence of: (1) equatorial breaks in myopic eyes versus nonmyopic eyes (P less than 0.005), and (2) earlier detachments for myopic eyes versus nonmyopic eyes (P less than 0.005). The presence of equatorial breaks seemed to be associated with earlier retinal detachments.

Aphakia, Postcataract↗
PubMed1988

Electrophysiological monitoring during acoustic neuroma and other posterior fossa surgery.

Techniques used to monitor the function of the seventh and eighth cranial nerves during acoustic neuroma and other posterior fossa surgery are reviewed. The auditory brainstem response (ABR), electrocochleogram (ECochG) and direct recording from the auditory nerve (CNAP) were compared. The best technique is the ECochG, although in many cases, the CNAP should be used as a back-up technique. The CNAP is especially useful for the identification of the auditory nerve. Both can provide real-time feedback on the physiological integrity of the auditory nerve. The ABR may be helpful in monitoring brainstem function. For some procedures, optimal monitoring requires the combined recording of all three techniques. Monopolar constant-voltage intracranial stimulation of the facial nerve is helpful for the identification and preservation of the facial nerve. Audio monitoring of spontaneous electromyographic activity provides real-time feedback on the effect of surgical manipulation of the nerve. Monitoring of ephaptic transmission in the facial nerve during microvascular decompression for hemifacial spasm aids in the identification of the offending vessel.

Action Potentials↗
PubMed1988

The effects of human insulin on antibody formation in pregnant diabetics and their newborns.

We studied the immunogenicity of human insulin in 11 diabetic mothers and their newborns. Serum antibody formation was assayed by two different methods. Upon switching four patients from beef/pork insulin to human insulin, we found that elevated baseline antibody levels in three women decreased, in two to undetectable levels at term. The fourth patient had undetectable antibody levels at baseline and borderline levels at term. Only one of their four newborns had antibodies. Upon initiation of insulin treatment in another five diabetics without detectable antibodies at baseline, only two developed antibodies, and only one of their newborns developed antibodies. Two other patients, initially not on insulin, had baseline elevations of antibody that decreased with administration of human insulin; both of their newborns had antibodies. Overt diabetes evolved subsequently in both mothers after pregnancy. We conclude the following: 1) Upon transfer from beef/pork insulin to human insulin, mothers and their newborns show a decrease in insulin antibodies; 2) new patients initiated on insulin develop low levels of antibodies, if any, and their newborns also have low levels of antibodies if any; and 3) the decreased or absent immunogenicity of human insulin supports its use in pregnant diabetics.

Adolescent↗
PubMed1979

Biochemical analyses of natural and induced null variants of Drosophila enzymes.

For the characterization of null mutants identified in Drosophila populations, several Drosophila enzymes including alcohol dehydrogenase, cytoplasmic malate dehydrogenase, alpha-glycerol phosphate dehydrogenase, and phosphoglucose isomerase were co-purified to homogeneity using an 8-(6-aminohexyl)-amino-ATP-Sepharose affinity column followed by DEAE-Sepharose column chromatography. Mitochondrial malate dehydrogenase was purified by the use of CM-Sepharose and the same ATP affinity column. Alcohol dehydrogenase and alpha-glycerol phosphate dehydrogenase were mapped on a two-dimensional gel. Antiserum was raised in rabbits against these Drosophila enzymes. The presence of cross-reacting material in null mutants was characterized by double immunodiffusion, immunoelectrophoresis, and two-dimensional gel electrophoresis. By immunological techniques, two natural null variants of malic enzyme and one of phosphoglucose isomerase were shown to be negative to cross-reacting material. Two low-dose-rate gamma-radiation-induced null mutants of cytoplasmic malate dehydrogenase were shown to be positive to cross-reacting material. Two-dimensional gel analyses enabled the characterization of three natural null variants of alpha-glycerol phosphate dehydrogenase. The viability of some null mutants with homozygous null or null/deficiency genotypes is discussed in terms of the in vivo metabolic roles of the related enzymes.

Alcohol Oxidoreductases↗
PubMed1979

Analyses of mouse and Drosophila proteins by two-dimensional gel electrophoresis.

Two-dimensional gel electrophoresis was employed for the protein analysis of several different mouse tissues and Drosophila. The number of protein spots detected with conventional protein dye staining techniques ranged from 110 in erythrocyte lysate to 320 in liver homogenate. Strain variation of protein spots on the gels was examined in five different tissues from two strains of inbred mice (DBA/2J and C57BL/6J) and their F1 hybrids. The protein spots which exhibited strain variation were shown to be autosomally inherited and to follow Mendelian genetics. From these analyses, it was shown that the frequencies of protein variations between these two strains of mice vary from 1 to 5% with the tissue examined. During the course of this study, the protein spots corresponding to nine muscle proteins and three testis enzymes from the mouse as well as two Drosophila enzymes were assigned on two-dimensional gels of their respective homogenates. Radioisotope labelling of Drosophila and autoradiography of the two-dimensional gels were also performed to improve the sensitivity and resolution of the technique. The potential application of two-dimensional gel electrophoresis for mutant screening as well as biochemical genetic studies is discussed.

Animals↗