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Biomedical subjects

G W Johnson

Publications and source records attributed to G W Johnson.

35 records · Page 2Linked to original sources
PubMed1988

Post-heparin triacylglycerol lipases in ovine plasma.

Lipoprotein lipase and hepatic lipase have been shown to be present in the post-heparin plasma of sheep. Intravenous injection of heparin into sheep produced a rapid increase in the free fatty acid concentration and lipolytic enzyme activity of the plasma, both peaking within 5-15 min and then falling to pre-heparin levels within 30-60 min. Lipolytic activity was not detected in plasma before heparin treatment. Two distinct lipolytic activities were separated from the plasma by chromatography on heparin-Sepharose 6B. Lipoprotein lipase was identified on the basis that the lipolytic activity was dependent upon the addition of plasma, inhibited by 1M NaCl, and inhibited by a specific antiserum against lipoprotein lipase. The second lipolytic activity of plasma was identified as hepatic lipase, as it was not dependent upon plasma for activity, nor was it inhibited by 1M NaCl or antiserum against lipoprotein lipase. Its properties were identical to the lipase extracted from the liver of sheep. Lipoprotein-lipase activity, but not hepatic-lipase activity, was dependent upon the nutritional state of the sheep at the time of heparin injection. However, hepatic lipase comprised a significant proportion of the total lipolytic activity.

Animals↗
PubMed1988

Fat embolism after liposuction.

We present a case of adult respiratory distress syndrome (ARDS) after extensive liposuction. On the basis of fever, tachypnea, hypoxia, and ARDS occurring within 48 hours after surgery without evidence of cardiogenic pulmonary edema or sepsis, the etiology is believed to be fat embolism. Although liposuction is generally an effective and safe procedure, awareness of this life-threatening complication is important in order to institute prompt and appropriate treatment. Fat embolism must be differentiated from thromboembolism, as the treatment is different, and heparin is not indicated. It is recommended that training standards and guidelines be devised in order to reduce morbidity and mortality associated with this procedure.

Abdomen↗
PubMed1987

The value of prophylactic antibiotics during the insertion of long-term indwelling silastic right atrial catheters in cancer patients.

Over a 3.5 year period from August 1982 to December 1985, 200 Hickman catheters (Evermed, Medina, WA) were inserted into patients at the King Faisal Specialist Hospital and Research Centre (KFSHRC), Riyadh, Saudi Arabia. One hundred sixty catheters were placed in patients with malignant disease, many of whom were immunosuppressed at the time of catheter insertion. Seventy of 160 (44%) patients received prophylactic antibiotics and 90 (56%) did not. The mean age of each group was 23 years (range, 2 to 70 years), and the patients in each group were statistically similar in sex, underlying disease, and routine preoperative hematologic and biochemical evaluation. Exit-site wound infections occurred in 50 of 90 (55.5%) patients who did not receive prophylaxis and in 12 of 70 (17%) patients who received prophylaxis (P less than 0.0001). There was no statistically significant difference in the incidence of tunnel and incision site infections. The mean duration of antibiotic prophylaxis was 2.9 days (SD, 1.2 days). Organisms cultured from catheter associated infections, included Staphylococcus epidermidis 36, S. aureus 30, Klebsiella pneumoniae 1, Pseudomonas aeruginosa 3, Escherichia coli 1, and diphtheroids non-CDC-JK 3. Vancomycin was used as antibiotic prophylaxis in 64 patients, Kefzol (Eli Lilly, Indianapolis, IN) in one, oxacillin in three, nafcillin in one, and Septra (Burroughs Wellcome, Research Triangle Park, NC) in one. The data indicate that the use of intravenous antibiotic prophylaxis significantly reduces exit site infection and may reduce both tunnel and incision site infection. Prophylactic antibiotic coverage should be provided to patients during insertion of long-term indwelling right atrial catheters.

Anemia, Aplastic↗
PubMed1987

Isolation of two distinct activator proteins for lipoprotein lipase from ovine plasma.

Two distinct activator proteins for lipoprotein lipase (LPL) have been isolated in approximately equal amounts from ovine plasma. These low molecular weight proteins were readily separated from each other on the basis of size and charge. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated proteins of Mr about 8000 and 5000, with pI in urea-containing gels of about 5.1 and 4.8 respectively. Each of the ovine activator proteins was as effective as human apolipoprotein C-II (apo C-II) in activating LPL, with 1 microgram/ml giving near to maximum activation, and in lowering the apparent Km of LPL for triolein substrate. As the ratio of activator to triolein increased from 0.16 to 5.2 (micrograms/mg) the apparent Km fell from about 0.5 to 0.18 mM. Whereas human apo C-II and the two ovine activators were equally effective in stimulating the hydrolysis of triolein, differences were observed between the human and ovine activators when p-nitrophenylbutyrate was used as substrate. Unlike human apo C-II, which produced significant inhibition of p-nitrophenylbutyrate hydrolysis, the ovine activators were without effect. This suggests that the interaction between the ovine activators and LPL is different from that of human apo C-II.

Animals↗
PubMed1987

cDNA cloning and chromosomal localization (4q11-13) of a gene for statherin, a regulator of calcium in saliva.

On the basis of the known amino acid sequence of statherin, a human salivary protein, mixed synthetic oligonucleotides were synthesized and used to screen a cDNA library constructed from human parotid-gland mRNA. A cDNA clone coding for statherin was isolated from this library and has been completely sequenced. The cDNA represents a full-length (or nearly full-length) copy of an approximately 640-bp statherin mRNA. Statherin appears to be coded by a single-copy gene that maps to chromosome 4q11-4q13 when somatic-cell hybrids are used.

Amino Acid Sequence↗
PubMed1986

Homodyne interferometer for basilar membrane vibration measurements. II. Hardware and techniques.

Selected mechanical features of the design of the homodyne interferometer are described. This interferometer was utilized for basilar membrane vibration measurements. The massive construction necessary to minimize mechanical vibration and noise is described. In order to measure basilar membrane vibrations, it was necessary to increase its reflectivity. Gold crystals were utilized as microscopic mirrors. The technique for fabrication of gold crystals is described. These crystals are small and fragile and required special handling. The method of picking up the crystals and placing them on a preselected location is described. In order to minimize the effect of the involuntary animal movements a reference mirror system is cemented to the skull. The design of the reference mirror system and the method of cementing it to the skull are described.

Animals↗
PubMed1983

Lipoprotein lipase of sheep and rat adipose tissues.

Lipoprotein lipase preparations were obtained by aqueous extraction of various tissues from sheep and rats. Preparations having high activity towards serum-activated triolein emulsions were obtained from actively growing sheep, provided that the tissue was maintained at 37 degrees C throughout the extraction procedure. Activity of lipoprotein lipase from sheep adipose tissue, like that from the rat, was dependent upon the presence of serum in the reaction mixture, and was optimal at pH 8-9. Inhibition of sheep adipose tissue preparations by protamine sulfate (1 mg/ml) and 0.6 M NaCl was similar to that found for rat adipose tissue preparations. The affinity of the lipoprotein lipase preparation for the activated substrate from sheep and rat adipose tissue was, however, markedly different; sheep preparations being activated at much lower substrate concentrations (Km 0.43 mM) than rat preparations (Km greater than 5 mM). These findings, confirmed with acetone-ether preparations of lipoprotein lipase, indicate that the enzyme from sheep adipose tissue has a greater potential to remove triacylglycerol from the plasma. This could result in a greater deposition of fat in the tissue.

Adipose Tissue↗
PubMed1981

Central core reduction mammoplasties and Marlex suspension of breast tissue.

The author describes a technique for central core reduction mammoplasty with the same technique being utilized for a mastopexy. By transposition of the nipple areolar complex, the nerve supply as well as the vascular supply is maintained on an inferiorly based dermal pedicle. This technique does not require the recall of a multitude of points or locations or other maneuvers necessary to do the markings to obtain a symmetric, aesthetically pleasing reduction. The author has also developed a technique for the use of Marlex Mesh to support the remaining breast tissue and, by attaching the mesh to the area of the second rib, the support of the breast tissue is converted from cutaneous origin to skeletal origin, giving an internal support of breast tissue and preventing subsequent early ptosis and loss in fullness of the upper portion of the breast. The mesh has been used in 43 patients over the past two years with no serious complications.

Breast↗
PubMed1981

Computer graphics in facial morphology analysis.

Stereophotogrammetry is an attractive technique for mapping changes in facial form and contour following surgery. The need for trained personnel, however, has prevented the technique from gaining wide use. We report the development of a stereophotogrammetric system in combination with an inter-graphics computer system which overcomes this and other limitations. An interactive computer graphics system is used to record, present and manipulate the three-dimensional data obtained from a digitized stereophotogrammetric picture. The system also permits measurement of morphological changes following surgery as well as volume changes and has the potential for use in indicating the order in which multistage procedures should be undertaken and the time delay before such surgeries.

Cephalometry↗