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Biomedical subjects

D H Clark

Publications and source records attributed to D H Clark.

At least 19 recordsLinked to original sources
PubMed1996

Prediction of live lamb chemical composition utilizing electromagnetic scanning (ToBEC).

Electromagnetic scanning was investigated to determine its accuracy in predicting chemical composition in live lambs. Forty-seven Rambouillet wether lambs were scanned with an electromagnetic instrument (ToBEC Model HA-2). Lambs were serially scanned and slaughtered over the weight range of 29.5 to 63.5 kg. Each lamb was scanned twice: before and immediately after 24 h of food deprivation. Chemical composition was determined from whole-animal ground samples by AOAC methods for percentage of DM, CP, ether extract (EE), and Ash. Percentage of fat-free mass (FFM) was calculated from the percentage of moisture and CP. Correlation and stepwise regression procedures were used to identify the most reliable independent variables for predicting chemical composition. Independent variables included electromagnetic scan data and live animal measures for weight, body length, and chest girth circumference. Electromagnetic data included the average scan response curve (PH0) and Fourier transformations (P1T, P1R, P2T, and P2R). Repeatability of the HA-2 model was extremely high (r = .98). Reliable prediction equations were obtained for DM, CP, EE, and FFM (R2 > .66). The percentage of ash could not be predicted from the independent variables. Electromagnetic scan responses contributed little to the model sum of squares. Body weight accounted for the majority of the model sum of squares. Depriving lambs of food for 24 h slightly improved the R2 value and significantly decreased scan responses (P < .01). Body weight was a better predictor of chemical composition over a large weight range than any of the scan responses. Further investigation of the HA-2 is needed to determine whether it is effective in determining differences in live body composition between animals of equal weight.

Animals↗
PubMed1995

Comparison of calf housing types and tympanic temperature rhythms in Holstein calves.

During fall, 30 Holstein calves were randomly assigned to three housing treatments from birth to weaning: conventional wooden hutches, enclosed molded polyethylene domes, and thermomolded opaque polymer hutches with ridge-top ventilation systems. The wooden and polymer hutches had outdoor pens. Fifteen calves, 5 in each housing type, were fitted with portable data loggers to record ambient (calf microclimate) and tympanic temperatures. Additional data collected included weekly girth, BW, and feed intake; blood samples were collected within 24 h of birth and at weaning (8 wk); and behavioral observations were made at 1, 4, and 7 wk of age. Polyethylene domes had the warmest microclimate, followed by wooden and polymer hutches. Feed intake, growth measurements, blood physiology, and behavior were unaffected by housing type. Diurnal tympanic temperature rhythms of neonatal dairy calves in this study were monophasic: maximums were at 1200 to 1700 h, and minimums were at 0600 to 0900 h. Computed fractal dimensions of tympanic temperature by week indicated a gradual diminishing of stress as the calves became older and acclimated to their environment. This objective characterization provides a basis for further evaluation of physiological stress and a means of improving environmental management.

Animals↗
PubMed1994

Comparison of AOAC and light spectroscopy analyses of uncooked, ground beef.

Ground beef samples (n = 302) were analyzed for DM and fat content with standard laboratory procedures. Samples were also analyzed by light spectroscopy with either a NIRSystems model 6250 or a model 6500. Samples were thawed at room temperature, packed in cups (three/sample), and scanned every 2 nm with the model 6250 in the mid wavelength (MW) region from 1,100 to 2,500 nm (MW-6250). Whirl-pak bags containing the thawed samples were also scanned every 2 nm with the model 6500 using a fiber optic attachment in the short wavelength (SW) region from 400 to 1,100 nm (SW-6500), 1,100 to 2,500 nm (MW-6500), and 400 to 2,500 nm (SW+MW-6500). Each sample was scanned at two different locations on the Whirl-pak bags. The MW-6250 produced the lowest standard errors of calibration (1.62 and 1.62%) and highest R2 values (.97 and .98) for DM and fat, respectively, during calibration. However, SW-6500 produced the lowest standard errors of performance (2.34 and 1.92%) and the highest r2 values (.86 and .95) for DM and fat, respectively, during validation. The MW-6500 and SW+MW-6500 produced intermediate results. Results with fiber optic scanning in the SW region were better than with cups and scanning in the MW region. Light spectroscopy for determining DM and fat content of ground beef samples can replace wet chemistry.

Animals↗
PubMed1994

An analysis of the value of forensic odontology in ten mass disasters.

The results of dental identification in ten mass disasters, in which British forensic odontologists undertook the dental identification procedures, are reported. These ten disasters indicate the difficulties associated with this method and draw attention to the need for national dental associations to deal with the problem of inadequate dental records and unmarked dentures. It is suggested that, through the FDI World Dental Federation, each member country should appoint dentists, responsible for providing advice and assistance, to forensic odontologists in other countries, when nationals of the country are victims of an international disaster.

Accidents↗
PubMed1988

Effect of sodium bicarbonate and magnesium oxide in an alfalfa-based total mixed ration fed to early lactating dairy cattle.

Forty-eight lactating Holstein cows were fed a total mixed ration of 57% concentrate and 43% forage (dry basis) for 12 wk postpartum. Treatments consisted of 1) no added buffers, 2) .4% MgO, 3) .8% NaHCO3, and 4) .8% NaHCO3 plus .4% MgO of the total ration DM. Body weight, DM intake, and milk yield and composition were unaffected by treatment. Gross efficiency of milk production was decreased by the addition of NaHCO3 or MgO. Buffer supplementation had no effect on ruminal volatile fatty acid concentration or blood chemistries.

Animal Feed↗
PubMed1986

Dental identification problems in the Abu Dhabi air accident.

The forensic odontological examination of 112 victims in the 1983 air accident near Abu Dhabi is described with particular reference to the problems encountered in the age assessment of the 26 children, and serves to illustrate that dental identification in aviation accidents may be of only limited application in Asian victims. Following this accident, other means of identification had misguidedly been removed by the recovery teams. Of those identified, half were by dental means alone, but this amounted to only 6.24% of the total number of victims.

Accidents, Aviation↗
PubMed1985

Excision of giant nevi in children--how should the wound be closed?

The cases of two children with giant nevi of the trunk that were excised and closed in early childhood are presented. Both had cosmetic and functional deformities and were treated by scar excision and skin grafting. The 2 cases demonstrate that excision and closure of giant nevi in young children should be discouraged, as it can result in distortion of surrounding structures.

Child↗
PubMed1985

Group B streptococcal necrotizing fasciitis arising from an episiotomy.

A case of extensive necrotizing fasciitis arising from an episiotomy is presented. Group B beta-hemolytic streptococcus and Staphylococcus aureus were isolated. Prompt recognition and aggressive therapy resulted in a favorable outcome despite significant morbidity. Salient clinical features of this rare postpartum complication are discussed and previous cases are reviewed. In addition to wide surgical resection, therapy included aggressive volume resuscitation with Swan-Ganz catheter monitoring, the use of military antishock trousers (MAST suit) to control diffuse hemorrhage, and temporary application of porcine xenografts.

Abdominal Muscles↗
PubMed1982

Closure of myelorachischisis defects with reverse latissimus dorsi myocutaneous flaps.

The closure of myelorachischisis defects has been difficult and at times complicated. Over the past 2 decades, the use of rotational advancement flaps has been increasingly popular, but can be attended by instances of skin ischemia and necrosis. The development of the myocutaneous and muscle flap concept has aided reconstructive surgery. Extensive experience with the useful latissimus dorsi flap with and without overlying skin has been obtained for the reconstruction of a variety of truncal defects. We describe the use of bilateral "reverse" latissimus dorsi muscle flaps based on the paraspinal perforators for the closure of myelorachischisis defects in two patients. Coverage was uneventful in both instances. A 2-year follow-up revealed no compromise of upper extremity function due to sacrifice of the latissimus dorsi muscles. We offer an approach to the problem of closure of large myelorachischisis defects: bilateral reverse latissimus dorsi muscle flaps and delayed skin coverage. This approach seems to offer a good muscle layer over the dural closure and to provide long-standing durable coverage without apparent compromise of upper extremity function.

Follow-Up Studies↗
PubMed1978

Evidence for thyroidal secretion of 3,3',5'-triiodothyronine in man and its control by TSH.

Thyroidal secretion of 3,3',5'-triiodothyronine (reverse T3, rT3) and its control by TSH was assessed by measuring (1) arterio-venous hormone gradients in patients undergoing surgery, (2) changes of hormone concentrations after induction of anaesthesia, and (3) changes induced by TRH administration. In ten patients in whom thyroid activity was under TSH control (parathyroidectomy and non-toxic goitre) increased thyroid vein/carotid artery ratios (TV/CA) for rT3 (mean TV/CA ratio 2.53) were found when compared to six patients with non-toxic goitre on suppressive doses of T4 (mean TV/CA ratio, 1.27) (P less than 0.05). The mean calculated operative secretion rate of rT3 was 12.5 microgram/day but only 2.4 microgram/day in patients receiving T4. In thirteen patients undergoing elective surgery induction of anaesthesia significantly increased rT3 levels. In nine euthyroid adults intravenous TRH (200 microgram) increased peripheral venous rT3 levels between 3 h (P less than 0.005) and 8 h (P less than 0.05) after the injection. It is concluded that significant amounts of rT3 are secreted by the thyroid gland at operation and this is, in part, under TSH control.

Adult↗