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Biomedical subjects

G W Davis

Publications and source records attributed to G W Davis.

18 recordsLinked to original sources
PubMed1991

Automated percutaneous discectomy.

Automated percutaneous discectomy is a new, safe procedure for treating herniated lumbar discs still contained by the annulus or posterior longitudinal ligament. In 1985, one of the authors reported a percutaneous nucleus aspiration technique using a 2-mm aspiration probe. This small probe produced minimal tissue damage, allowing the procedure to be done on an outpatient. In this series, 518 patients were treated using this technique for an overall success rate of 85%. Compensation patients, elderly patients, and patients with previous surgery were treated successfully using percutaneous discectomy on an outpatient basis. No intraoperative or postoperative complications occurred.

Adult↗
PubMed1991

Estimates of beef carcass intermuscular fat.

Three experienced persons evaluated 158 carcasses 24 h postmortem for USDA yield grade (YG) and quality grade factors, nine subcutaneous (SC) fat indicators, and four intermuscular (IM) fat indicators. Forty sides (YG 1.1 to 3.8) were selected for determination of chemical composition, two measures of cutability, and total IM fat from the round, loin, rib, and chuck. The IM fat estimates at the 12th rib, rib-plate juncture, and 5th rib were correlated with percentage of chemical fat (r = -.72, -.70, and -.55, respectively). Simultaneous consideration of YG factors accounted for 61% of the variation in chemical fat. Substituting the IM fat estimate at the 12th rib for adjusted fat thickness (AFT) in the equation explained 60% of the variation in percentage of chemical fat. An equation containing two IM fat estimates, marbling score and longissimus muscle area explained 68% of the variation in chemical fat. Simultaneous consideration of the YG factors accounted for 59% of the variation in boneless, closely trimmed (6 mm SC fat and no IM fat) retail cuts from the round, loin, rib, and chuck. Substituting the IM fat estimate at the 12th rib for AFT in the equation accounted for 65% of the variation. These data from a fairly uniform set of steer carcasses show that percentage of chemical fat and cutability can be reliably predicted from IM fat estimates and other traits that can be visually estimated on hot-fat trimmed carcasses.

Adipose Tissue↗
PubMed1991

Relationships between pork loin palatability traits and physical characteristics of cooked chops.

Pork loins (n = 72) were selected so that marbling scores would range from "practically devoid" to "abundant" in the longissimus muscle. Loin chops were cooked and rated by a trained six-member sensory panel. Physical and chemical characteristics were stratified according to marbling level (divided into 10 subclasses), muscle structure, shear force, overall palatability, and juiciness (each divided into three subclasses). The highest ratings for overall palatability were assigned to chops with high reflectance (685 nm), low moisture (70.1%), high i.m. fat (9.1%; or, high marbling score), low protein (19.4%), and low cooking loss (25.9%). Chops with the highest percentage of cooking loss were high in moisture content (75.59%), low in i.m. fat (1.78%), and high in protein content (21.54%). Differences in muscle structure, shear force, overall palatability, and juiciness were associated with differences in percentages of protein, moisture (whole tissue basis [WTB]) and fat (WTB). Pork loins with marbling between "practically devoid-plus" and "small" had (P less than .05) more protein and less fat (WTB) than loins with marbling scores between "modest" and "abundant." Loins with overall palatability ratings between 4.0 and 6.0 had more moisture and protein (P less than .05) than did loins with palatability ratings of 6.1 to 8.0. Selecting pork loins with "small" or less marbling, extremely open structure, a juicy rating of "slightly juicy," and an overall palatability rating of "like slightly" would identify fresh loins that had lower fat and(or) higher protein content.

Animals↗
PubMed1990

Effects of infused glucose, sodium and potassium chlorides and polyphosphates on palatability of hot-boned pork.

Longissimus muscle sections were excised from eight pork carcasses 1 h postmortem and sectioned into six .5-kg roasts to determine the effects of glucose, salt and polyphosphates (aqueous solution to 110% of fresh weight) on palatability of hot-boned pork. Treatments were hot-boned control (HB) with no infusion or infusions of 2% KCl and 3% of a 1:1 mixture of sodium hexametaphosphate and sodium pyrophosphate (PP) plus either 8% NaCl; 2% glucose (G) plus 6% NaCl; 6% G plus 2% NaCl; or 8% G. Another muscle section was chilled at 0 degrees C for 24 h on each carcass as a cold-processed control (CP). The roasts were frozen until cooked and evaluated by a sensory panel. The infused groups were more tender, juicy and salty and higher in moisture and ash but lower in protein content than either the CP or HB controls (P less than .05). The fat content of the infused groups was lower than of the HB control but was not different from that of the CP control. Either 2% NaCl plus 6% G or equal amounts (4%) of NaCl and G produced the most tender and juicy product. The substitution of 4% glucose for NaCl not only reduced the NaCl content of the infusion solution, but also improved the palatability of the meat. This substitution allows production of a hot-boned, lower-sodium precooked pork that is tender and juicy.

Animals↗
PubMed1989

Automated percutaneous lumbar discectomy.

Lumbar spine disc disease has traditionally been treated surgically by laminectomy and manual removal of the offending disc material. Chymopapain was extensively used to decompress the disc pressure in a relatively noninvasive manner, but has been abandoned due to serious complications, including anaphylaxis and paraplegia. Onik introduced automated percutaneous discectomy in 1985. This procedure has proved safe and efficacious for treating lumbar disc disease without complications. It is performed on an out-patient basis under local anesthesia with minimal rehabilitation time. The success rate reported in a multiinstitutional study with one year follow-up is approximately 75%. The majority of failures occur in patients with free fragments or spinal stenosis - both of which can be diagnosed preoperatively with good imaging examinations. Hence, the success rate can be expected to improve if preoperative imaging is relied upon to help choose appropriate patients. Over 30,000 percutaneous discectomy procedures have been performed. The only complication reported, disc infection, developed in fewer than 0.2% of cases. Automated percutaneous discectomy has the potential to treat a vast number of patients with lumbar disc disease who otherwise would have laminectomies.

Fluoroscopy↗
PubMed1989

Retrorenal colon: implications for percutaneous diskectomy.

It has been recommended that computed tomography (CT) with the patient prone be performed in every patient undergoing percutaneous diskectomy; this would enable detection of a retrorenal location of the colon, which could interfere with the percutaneous procedure. In this evaluation of 346 prone CT studies, only one patient (0.29%) was found to have retrorenal or retropsoas bowel that would have been perforated at diskectomy. Because of this extremely low prevalence, the performance of prone CT in every patient undergoing percutaneous lumbar diskectomy is not believed to be necessary.

Adolescent↗
PubMed1989

Clinical experience with automated percutaneous lumbar discectomy.

Percutaneous automated aspiration discectomy is a new procedure for treating uncomplicated herniated lumbar discs. In a series of 200 patients, followed for up to six months, the overall success rate was 77.5%. Workers' compensation claimants, elderly patients, and patients with previous surgery can be treated successfully using percutaneous discectomy. Patients were treated on an outpatient basis. Patients returned to work significantly sooner after percutaneous discectomy than after microdiscectomy or laminectomy. No intraoperative or postoperative complications occurred.

Adult↗
PubMed1989

Automated percutaneous discectomy at the L5-S1 level. Use of a curved cannula.

Previously, a major limitation to percutaneous disc decompression to relieve symptoms of sciatica was the inability to approach the L5-S1 level. Obstruction by the iliac crest prevented the instrumentation from entering the L5-S1 disc space. In this paper, the authors describe a curved cannula which can be placed down to the L5-S1 disc space over a straight trocar that has been anchored at the annulus. The cannula bends the flexible aspiration probe back into the plane of the disc so that it is no longer obstructed by the sacral end plate. Using this system, the L5-S1 disc space was successfully removed in 90% of 30 cases.

Catheterization↗
PubMed1987

Cholesterol concentration of longissimus muscle, subcutaneous fat and serum of two beef cattle breed types.

The cholesterol concentration of uncooked and cooked longissimus muscle, uncooked subcutaneous fat and serum, as affected by days on feed, breed type and sex class in a factorial arrangement, and the relationship between serum cholesterol and tissue cholesterol were studied. Days on feed, breed type and sex class had no effect (P greater than .05) on tissue cholesterol concentrations. Overall least-squares means for uncooked and cooked longissimus muscle and subcutaneous fat were 63.32, 80.27 and 98.90 mg of cholesterol/100 g of tissue, respectively. Cholesterol concentration was 26.8% higher in cooked vs uncooked muscle and 56.2% higher in uncooked subcutaneous fat compared with uncooked muscle. Serum cholesterol concentration was lower (P less than .05) for fullblood Chianinas and steers (122.6 and 133.9 mg/dl) compared with crossbreds and heifers (162.3 and 151.0 mg/dl), respectively. Serum cholesterol concentration showed a cubic response (P less than .05) over days on feed; it was lowest at 0 d (79.6 mg/dl), increased up to 77 d (156.3 mg/dl), leveled off (154.7 mg/dl), then increased again (179.3 mg/dl). Serum cholesterol had low and insignificant correlation coefficients with all tissue cholesterol concentrations (r = .08 to .22; P greater than .05). Results indicate that muscle and fat tissue cholesterol concentrations do not vary in response to the differences in breed type, sex class or time on feed represented in the present study and thus may be an inherent characteristic dependent upon quantitative needs for cellular membrane functions. However, serum cholesterol concentration was affected by treatments evaluated in this study and may be related to factors affecting lipid metabolism.

Adipose Tissue↗
PubMed1976

Effect of systemic BCG infection in syrian golden hamsters.

The response of Syrian golden hamsters to systemic infection with several doses of Mycobacterium bovis (strain BCG) was assessed. Large numbers of organisms (10(7)), injected intravenously, were lethal for hamsters, whereas all animals survived infection with 10(4) colony-forming units of BCG. Animals responded immunologically to purified protein derivative as assessed by increased footpad swelling and splenic lymphocyte proliferation. The immediate cause of death was a diffuse granulomatous interstitial pneumonia.

Animals↗
PubMed1976

Experimental oncornavirus vaccines in the cat.

An experimental approach to the immunoprophylatic control of feline oncornavirus-mediated diseases has included induction of antivirus immunity and antibodies to the feline oncornavirus-associated membrane (tumor) antigens. A suitable model for exploring the effectiveness of killed oncornavirus vaccines in the cat has been provided by the use of feline sarcoma virus. Immunization of seven pregnant queens over a 6-week period with ultraviolet light-inactivated Gardner-Arnstein feline sarcoma virus resulted in significant protection among 12 kittens challenged with a tumor-forming Dose 90 at 7 days of age. This immunity was not present in kittens challenged at 35 days of age. Among 12 kittens born of queens immunized during pregnancy with ultraviolet light-inactivated Kawakami-Theilen feline leukemia virus and challenged with the same live virus at 4 days of age, significant protection was noted, ranging from prolongation of survival time to complete protection in 3 kittens. In general, the higher the antibody titer in the mother, the more effective the protection afforded the kittens. Immunization of 43 kittens during their first 5 weeks of life with the same vaccines used in adult cats did not immunize sufficiently to protect against feline sarcoma virus challenge at 5 weeks of age. Neutralizing antibody responses in these kittens were significantly lower than in pregnant queens. That kittens of this age are immunologically responsive was established, since complete protection of 9 kittens to feline sarcoma virus was obtained by immunization with a crude tumor extract inactivated with 5 to 7 megarads of gamma-irradiation. All these kittens developed feline oncornavirus-associated membrane antibodies while 3 developed demonstrable levels of virus-neutralizing antibodies. The results of these studies are believed indicative that killed virus vaccines and tumor vaccines can be effective immunoprophylatic measures in the control of RNA tumor virus oncogenesis in the cat. Developments in this model system should be relevant to any consideration given similar vaccines in humans.

Age Factors↗
PubMed1971

Effect of relative humidity on dynamic aerosols of adenovirus 12.

Dynamic aerosols of adenovirus 12 were generated in the same Henderson apparatus under conditions of high, medium, and low relative humidity. High relative humidities resulted in more recovery of adenovirus 12 from aerosols and lungs of newborn Syrian hamsters. At 89, 51, and 32% relative humidity, the total infectious virus recovered from a 20-min aerosol was 10(6.7), 10(6.0), and 10(4.3) TCD(50), respectively. Hamsters exposed to these 20-min aerosols retained measured lung doses of 10(3.0), 10(2.4), and 10(1.0) TCD(50), respectively. The measured retained lung doses were compared to calculated inhaled lung doses based on both total virus aerosolized and total virus recovery from the aerosols.

Adenoviridae↗