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Biomedical subjects

D Benson

Publications and source records attributed to D Benson.

At least 19 recordsLinked to original sources
PubMed1992

Patient experiences with multiband full dynamic range compression.

This investigation compared performance for 18 experienced hearing aid patients with a multiband full dynamic range compression hearing device and their previously worn linear or automatic gain control hearing aids. Performance was evaluated using a variety of clinical tests. These included functional gain and dynamic range measurements, speech recognition, and real ear measurements. Patients rated their performance with the multiband compression device and their previously worn aids on a rating scale pertaining to a variety of real life listening situations. Statistical analysis of data derived from test results shows significantly improved performance on all measures using the multiband compression aid over their conventional aids. Patients rated their performance higher with the compression instrument than with the conventional aids. Differences in performance on clinical tests and subjective patient responses appear to be related to the different signal processing schemes used in the two groups of devices.

Adolescent↗
PubMed1991

Clenbuterol decreases catabolism and increases hypermetabolism in burned rats.

Following a 30% body surface area full-thickness open-flame burn, rats exhibited hypermetabolism, body weight loss, and muscle catabolism. Twenty-one days of treatment of one group of burned rats with the selective beta 2-adrenergic agonist, clenbuterol, increased resting energy expenditure and normalized body weight gain, muscle mass, and muscle protein content. Conversely, similar treatment of another group of burned rats with the long-acting beta-adrenergic antagonist, nadolol, reduced muscle mass, while having no effect on resting energy expenditure, body weight gain, or muscle protein content. These results demonstrate that hypermetabolism does not invariably result in loss of lean body mass and suggest that clenbuterol may be useful in preserving muscle mass and protein in catabolic diseases.

Amino Acids↗
PubMed1990

Regulation of total and myofibrillar protein breakdown in rat extensor digitorum longus and soleus muscle incubated flaccid or at resting length.

The present study characterized total and myofibrillar protein breakdown rates in a muscle preparation frequently used in vitro, i.e. incubated extensor digitorum longus (EDL) and soleus (SOL) muscles of young rats. Total and myofibrillar protein breakdown rates were assessed by determining net production by the incubated muscles of tyrosine and 3-methylhistidine (3-MH) respectively. Both amino acids were determined by h.p.l.c. Both total and myofibrillar protein breakdown rates were higher in SOL than in EDL muscles and were decreased by incubating the muscles maintained at resting length, rather than flaccid. After fasting for 72 h, total protein breakdown (i.e. tyrosine release) was increased by 73% and 138% in EDL muscles incubated flaccid and at resting length respectively. Net production of tyrosine by SOL muscle was not significantly altered by fasting. In contrast, myofibrillar protein degradation (i.e. 3-MH release) was markedly increased by fasting in both muscles. When tissue was incubated in the presence of 1 munit of insulin/ml, total protein breakdown rate was inhibited by 17-20%, and the response to the hormone was similar in muscles incubated flaccid or at resting length. In contrast, myofibrillar protein breakdown rate was not altered by insulin in any of the muscle preparations. The results support the concepts of individual regulation of myofibrillar and non-myofibrillar proteins and of different effects of various conditions on protein breakdown in different types of skeletal muscle. Thus determination of both tyrosine and 3-MH production in red and white muscle is important for a more complete understanding of protein regulation in skeletal muscle.

Animals↗
PubMed1990

A comparison of parallel versus perpendicular placement of retention sutures in abdominal wound closure.

A new technique for placement of retention sutures is described. Twenty-five rats underwent midline laparotomy incision. The control group was closed with traditional placement of through-and-through retention sutures placed in a perpendicular direction to the wound. The experimental group was closed with retention sutures placed in a parallel direction to the wound as described below. Wound bursting strength was significantly (P less than 0.001) greater at one to five days in the experimental group compared with the control animals. In addition, inflammatory reaction and pressure necrosis were greater in the control group. It appears that parallel placement of sutures has less of a tendency to cut through tissue when subjected to the distracting forces on a midline wound.

Abdomen↗
PubMed1989

Effects of bone marrow transplantation and polyinosinic-polycytidylic acid (poly I:C) on the rescue of animals from busulfan-induced NK suppression.

Repeated injections of busulfan (Bu) in CAF1 mice caused a long-lasting (greater than 16 weeks) decrease in their natural killer (NK) cell activity and impaired their resistance to transplantable lymphoma. Bu-treated mice had fewer spleen cells capable of binding to NK-sensitive YAC-1 target cells and reduced lymphokine-activated killer (LAK) cell activity as compared to normal age-matched controls. In contrast, interleukin 1 (IL-1) and interleukin 2 (IL-2) production were normal. Transplantation of normal bone marrow cells into Bu-treated mice resulted in an elevation of IL-2 production as well as in complete restoration of NK activity, target cell binding, and partial restoration of LAK activity. Resistance to transplantable lymphoma was equal to that of age-matched control mice. Polyinosinic-polycytidylic acid (Poly I:C) treatment resulted in immunomodulation in both control and Bu-pretreated mice. Twenty-four hours after Poly I:C injection, control and Bu-treated mice had higher levels of NK activity than did normal age-matched control mice, but the NK activity of Poly I:C/Bu-treated mice remained significantly lower than that of Poly I:C/control mice. The super-normal levels of NK activity in control and Bu-treated mice following Poly I:C administration were attributable, in part, to endogenous LAK activity. The generation of splenic LAK cells in vitro and target binding cells, which were reduced in Bu-pretreated mice, normalized following treatment with Poly I:C. Poly I:C treatment caused an increase in both IL-1 and IL-2 production in control and Bu-pretreated mice and in the ability of the treated mice to reject transplanted lymphoma cells. These results suggest that repeated injections of Bu decrease NK and LAK activity, but do not eliminate NK and LAK precursor cells. Thus, treatment with agents that increase IL-2 and/or interferon production can activate these cells to become effective killers and counter the long-lasting immunosuppressive effects of chemotherapy.

Animals↗
PubMed1988

Collagen crosslinking and cartilage glycosaminoglycan composition in normal and scoliotic chickens.

The amounts of lysine-derived crosslinks in collagens from tendon, cartilage, intervertebral disc, and bone and changes in the composition of sternal cartilage glycosaminoglycans were estimated in two lines of chickens, a control-isogenic line and a line that develops scoliosis. In the scoliotic line, scoliosis first appears at 3-4 weeks and progressively increases in severity and incidence so that 90% of the birds express the lesion by week 10. We have reported previously that cartilage, tendon, and bone collagens from scoliotic birds are more soluble than corresponding collagens from normal birds. Herein, collagen crosslinking and altered proteoglycan metabolism are examined as possible mechanisms for the differences in collagen solubility. At 1 week of age there were fewer reducible crosslinking amino acids (hydroxylysinonorleucine, dihydroxylysinonorleucine, and lysinonorleucine) in collagens from sternal cartilage and tendon in the scoliotic line than in the isogenic line. However, by week 3 and at weeks 5 or 7 values were similar in both groups. The amounts of hydroxypyridinium in vertebral bone and intervertebral disc collagen were also similar in both groups of birds. Consequently, differences in collagen crosslinking do not appear to be a persistent developmental defect underlying the expression of scoliosis in the model. However, differences were observed in cartilage proteoglycans and glycosaminoglycans from the scoliotic line that were not present in cartilage from the isogenic line. The average molecular weight of the uronide-containing glycosaminoglycans was 30% less in the scoliotic line than in the isogenic line, i.e., 12,000 compared to 18,000. The size distribution of cartilage proteoglycans from the scoliotic line also differed from that of proteoglycans from the isogenic line.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

An optimal morphometric method for quantitating wound epithelization.

A new, inexpensive method for quantitative evaluation of reepithelization of shallow split thickness wounds in piglets is described. Wounds, 2.2 X 2.2 cm and 0.4 mm depth are inflicted by an electro-keratome knife in domestic piglets. At a specific time after wounding, the wound area is excised and processed for histology. A computer simulation, based on a randomized systematic sectioning of an entire wound, was used to conclude that only eight sections from the 2.2 X 2.2 cm wound are needed for the final evaluation. The results showed that the above method allows for determination of the epithelization magnitude within +/- 5% at a 95% confidence limit. It was found that in 15 kg piglets 50% epithelization of the above wounds was achieved in 65 hr; however, there exists a great interindividual variability. The rate of epithelization is age dependent and significantly faster in 7 kg body weight piglets than in those weighing 40 kg. The epithelization rate was the same at both the wound edge and the center of the wound, stressing the importance of hair follicles as a source of epithelization.

Animals↗
PubMed1986

The QIP form: the one-page quality assurance tool.

Recognition of the need to document and track corrective action plans led to the development in 1980 of the quality improvement plan (QIP). The QIP form includes ten categories such as quality assurance (QA) assessment and initiator's recommendation; it helps provide information for the hospital QA committee and the QA program. The QIP form has helped identify 50 current QA concerns at the Methodist Hospital of Indiana, Inc., in Indianapolis indicating its successful implementation.

Accreditation↗
PubMed1985

Intraoperative sonographic monitoring of reduction of thoracolumbar burst fractures.

Intraoperative real-time sonography was used to monitor surgical reduction of acute thoracolumbar burst fractures in eight patients. Real-time sonography was performed after laminectomy through a saline-filled operative field using either a 5.0 or a 7.5 MHz transducer. Sonography was performed during Harrington rod distraction and during fracture reduction to confirm adequacy of decompression of the spinal canal. This technique is useful to monitor surgery and in defining adequate fracture reduction.

Adult↗
PubMed1977

The influence of freezing and freeze-drying of tissue specimens on enzyme activity.

In the presented study the influence of freezing and freeze-drying on enzyme activity is described. Attention is paid to 16 enzymes which can be used for quantitative enzyme histochemical techniques. With the exception of succinate dehydrogenase only, no significant inactivation during freezing and freeze-drying procedures could be demonstrated with lactate dehydrogenase, malate dehydrogenase (NAD+), malate dehydrogenase (decarboxylating) (NADP+), isocitrate dehydrogenase (NADP+), glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, NADH-oxydoreductase, mitochondrial glycerol-3-phosphate dehydrogenase, cytochrome c oxidase, phosphoglucomutase, glucosephosphate isomerase, glucose-6-phosphatase, acid phosphatase, beta-glucuronidase and non specific aryl esterase. Therefore, the results supply a sound foundation for those quantitative enzyme histochemical techniques in which tissue specimens are frozen or frozen-dried before enzyme estimations are performed.

Animals↗
PubMed1977

Tissue considerations for mandibular subperiosteal implants.

The criteria for the preoperative evaluation of the residual alveolar tissue for a potential implant patient have been discussed. To ensure a firm epithelial attachment around the implant post, the residual tissue at the point of oral penetration should be: (1) sufficient in amount or thickness and attached to the periosteum, (2) fibrous, not loose, areolar mucosa, and (3) positioned midway over the stress-bearing area for the implant and overlying prosthesis. If the existing tissue does not meet the above criteria, a free palatal graft can be placed over the point of oral penetration to improve the potential for tissue adaptation around the post.

Alveolar Process↗