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Biomedical subjects

J Davis

Publications and source records attributed to J Davis.

At least 217 records · Page 12Linked to original sources
PubMed1995

Effects of tumor necrosis factor alpha and vascular permeability factor on neovascularization of the rabbit ear flap.

OBJECTIVE: The survival of compromised skin flaps depends on neovascularization for their nutrition and metabolic waste removal. Our study investigated the effectiveness of angiogenic factors in accelerating peripheral neovascularization and in increasing skin flap viability. DESIGN: We elevated pedicled dorsal skin flaps on the ears of 23 New Zealand white rabbits, and the vascular pedicle was ligated to achieve partial flap necrosis. Fifteen flaps were treated with 0.1 micrograms/mL vascular permeability factor, and eight flaps were treated with 1.0 micrograms/mL tumor necrosis factor alpha. The ear flaps that were not treated with growth factor functioned in each rabbit as a normal saline control. MAIN OUTCOME MEASURES: The viability of skin flaps was observed visually and was measured by Cartesian planimetry using templates. Neovascularization was documented by microangiography and by histologic analysis of the flaps. RESULTS: Although the angiogenic factors accelerated neovascularization, increased flap survival was demonstrated only in those animals treated with vascular permeability factor that was supplied by an absorbable gelatin sponge. CONCLUSION: This experimental model, despite different levels of controls, contains multiple variables, including the use of an absorbable gelatin sponge, seroma formation, bioactivity of the angiogenic factors, optimal dosages and dosimetry, the need for a "blinded" format, and the validity of the histologic analysis. Additional investigation must be done and the experimental model itself must be improved before these apparently positive results may be accepted as clinically useful.

Animals↗
PubMed1995

Bowel obstruction in cancer patients.

OBJECTIVE: To examine the efficacy of various interventions on bowel obstruction occurring in patients with a history of cancer. DESIGN: Retrospective case series. SETTING: A university comprehensive cancer center. PATIENTS: Sixty-one patients presenting with 81 episodes of intestinal obstruction. RESULTS: Sixty-nine episodes of obstruction affected the small bowel, including 24 complete obstructions. There were 12 episodes of large-bowel obstruction, eight of which were complete. Five patients (8.2%) had concurrent small- and large-bowel obstruction. In 59 cases, the cause was established: 36 (61%) were due to metastatic tumor and 23 (39%) were due to benign conditions. Of the 49 episodes of partial bowel obstruction, 42 (86%) initially were treated medically. Nineteen (45%) of these 42 cases of obstruction resolved after 8.7 +/- 11.1 days (mean +/- SD) of conservative management. Twenty-two patients with partial obstruction were treated surgically, with relief of obstruction in 15 cases (68%). Of the 32 episodes of complete obstruction, 26 (81%) were initially managed conservatively; in only one case (3.8%) did obstruction resolve. Surgery successfully relieved the obstruction in 16 (76%) of 21 patients. Twenty-six patients received parenteral nutrition at home as the major treatment for obstruction; 22 (85%) experienced relief of nausea and vomiting. Patients with malignant obstructions survived 0 to 24 months (median, 4.7 months); the median survival for those treated surgically was 5.0 months. CONCLUSIONS: In patients with a history of cancer, partial obstruction (but not complete obstruction) frequently resolves with medical management. Surgical intervention relieves most cases of partial or complete obstruction regardless of benign or malignant cause, but survival often is limited in the latter group. The entire intestinal tract should be evaluated in all patients, since 8.2% of patients in this series had concurrent small- and large-bowel obstructions. Home parenteral nutrition often provides symptomatic palliation in patients not amenable to surgical relief.

Activities of Daily Living↗
PubMed1995

Predicting vertebral deformity using bone densitometry at various skeletal sites and calcaneus ultrasound.

We investigated the usefulness of bone density measurements from multiple skeletal sites and calcaneus ultrasound for evaluating the probability of vertebral deformation. Bone mineral density (BMD) was measured at the second metacarpal and middle phalanges using radiographic absorptiometry of hand radiographs, and at the lumbar spine using dual-energy x-ray absorptiometry. Distal radius and proximal radius were measured using single-energy x-ray absorptiometry (SXA), expressed as bone mineral content (BMC, grams per centimeter), and as BMD (grams per square centimeter). The calcaneus was measured using both SXA (BMD) and broadband ultrasound attenuation (BUA). Among the women in this study (mean age 74, SD = 5), 84 women developed new vertebral deformations (57 cases with one and 27 cases with two or more deformations), which were identified on serial radiographs during an average of 9 years prior to the measurements of bone density. Logistic regression analysis was used to calculate odds ratios for risk of deformation corresponding to a 1-SD difference in density or ultrasound, adjusted for age. All bone measurements were significantly associated with vertebral deformation, with odds ratios (95% confidence intervals) ranging from 1.40 (1.10, 1.78) for proximal radius BMD to 1.88 (1.45, 2.44) for calcaneus BMD measurements. Measurements of calcaneal BUA, calcaneal BMD, and hand BMD generally remained significant when included simultaneously with another measurement in the same model, suggesting that spine or radius BMD may not provide much additional information about risk of deformation. It appears that all of the measurements of bone density and ultrasound provide useful information regarding the probability of deformation. These findings await confirmation in a prospective study.

Absorptiometry, Photon↗
PubMed1995

Interpersonal distance and coping in children with HIV and cancer.

We compared interpersonal distance and coping among two groups of pre-school pediatric patients diagnosed with either HIV or cancer and a third group of healthy children. In comparison to the children with cancer, children with HIV indicated greater mother-child interpersonal distance--a finding that correlated with mothers' reports of social withdrawal. Other notable findings included increased father-child distance in the HIV population and mother-child discrepancies of perceived interpersonal distance. In addition, seven of the children with HIV indicated that the adults turn away--a finding that correlated with the children's knowledge of their illness. We also explored the possible role of protective communication in the pediatric HIV population.

Adaptation, Psychological↗
PubMed1995

Effect of outdoor airborne particulate matter on daily death counts.

To investigate the possible relationship between airborne particulate matter and mortality, we developed regression models of daily mortality counts using meteorological covariates and measures of outdoor PM10. Our analyses included data from Cook County, Illinois, and Salt Lake County, Utah. We found no evidence that particulate matter < or = 10 microns (PM10) contributes to excess mortality in Salt Lake County, Utah. In Cook County, Illinois, we found evidence of a positive PM10 effect in spring and autumn, but not in winter and summer. We conclude that the reported effects of particulates on mortality are unconfirmed.

Air Pollutants↗
PubMed1995

Applied physiology of rugby league.

Rugby League is a game of physical contact that involves low-intensity, aerobic exercise, combined with periods of intermittent, intensive anaerobic exercise. Matches consist of two halves, each of 40 minutes, separated by a 10-minute recovery period, and are contested by 2 teams of 13 players (6 forwards and 7 backs). Whilst the amount of time spent by individual players on low-intensity exercise exceeds the duration of high-intensity exercise, the nature of the high-intensity efforts (involving sprinting, lower- and upper-body impacts and high force generation) is such that the overall intensity of the game is greatly increased. Individual players have been shown to cover distances of approximately 5000 to 8000m a game, and be involved in 20 to 40 tackles. Maximum oxygen uptake (VO2max) values of around 56 ml/kg/min have been reported for rugby league players, with no differences between the values of forwards and backs. Forwards have, however, been shown to generally have higher body mass, subcutaneous fat and fat-free mass levels than backs. Backs have been found to be quicker than forwards and produce greater leg power output when related to fat-free mass. The amount of physiological data on rugby league players and the sport of rugby league is very limited, and there is considerable scope for future research in this area.

Body Mass Index↗
PubMed1995

Possible involvement of prostaglandin H synthase-1 induction in the differentiation of U-937 cells.

The promyelocytic human cell line U937, cultured in the presence of TPA and/or vit. D3, differentiates to monocytes and to macrophage-like cells. A potent stimulus for differentiation is represented also by colony stimulating factor-1 (CSF-1). Since this factor is a strong inducer of PGH synthase in human monocytes, we have investigated whether this event may be connected to the differentiation of U937. We have found that TPA, in the presence of serum, increased the production of thromboxane B2 (TXB2) 4-5 fold, while DMSO, which induced differentiation to neutrophils, was not active. Here we report studies indicating that the effect of protein and RNA synthesis inhibitors on prostanoid production, in cells incubated in the presence of CSF-1 (or FCS), can be correlated with an inductive event carried out by the growth factor, as demonstrated by the use of Western and Northern blotting procedures. However, while in human monocytes PGH-s and its mRNA are absent in controls and are expressed at high levels in CSF-1 stimulated cells, in U937 cells exposed to TPA, PGH-s mRNA was clearly detected by Northern blots, but its translation product was expressed at low level, and cells generated low amounts of TXA2 (13% of maximal production). After incubation with CSF-1 (or FCS) mRNA levels were only slightly modified, but large amounts of TXA2 accumulated in the medium. We have interpreted these findings by suggesting that CSF-1 is capable not only of regulating the expression of the gene encoding PGHs, but also of acing translationally to regulate the expression of its mature mRNA.

Blotting, Western↗
PubMed1995

Influence of local treatment on the recurrence rate of ductal carcinoma in situ.

BACKGROUND: Screening mammography has resulted in a significant increase in the diagnosis of ductal carcinoma in situ (DCIS). The role of breast conservation therapy and the long-term recurrence rate are still controversial. This article compares mastectomy, wide excision alone, and wide excision with radiation as treatments for DCIS. STUDY DESIGN: One hundred twenty-four cases of DCIS were retrospectively reviewed and were found to be pure DCIS by a senior pathologist. The mean age at diagnosis was 60 years (range, 33 to 81). Originally, 101 patients (81 percent) presented with calcification on mammogram, and 23 (19 percent) presented with a palpable mass. Histologic data showed that 54 (44 percent) had noncomedo type lesions, 46 (37 percent) had comedo type, and 24 (19 percent) had unknown type DCIS. RESULTS: Four of the 124 patients had a recurrence during a mean follow-up period of 43 months. Recurrence is defined as any development of DCIS or invasive carcinoma in the ipsilateral breast. There was one (1.3 percent) recurrence in the 75 patients treated with mastectomy (an adenocarcinoma of the chest wall), which occurred at 59 months. Treatment was 5,750 cGy to the chest wall and the patient is free of disease 37 months postradiation. There were three (11 percent) recurrences at 14, 21, and 29 months, respectively, in the 28 patients treated with wide excision alone. All three recurrences were found by calcifications on mammogram and all patients had comedo type original lesions. Two recurrences were pure DCIS of the breast. Both patients were treated with mastectomy and are free of disease at 33 and five months, respectively. The third recurrence was an invasive colloid carcinoma of the breast. Treatment was a modified radical mastectomy; the patient is free of disease after 62 months. There were no recurrences in the 21 patients who were treated with wide excision and radiation. Average total dose of radiation was 5,835 cGy (range, 4,500 to 6,480). CONCLUSIONS: The results of this study indicate that both mastectomy and wide excision with radiation are associated with very low recurrence rates. Wide excision alone is associated with a higher recurrence rate. However, all recurrences were detected mammographically and all lesions were salvaged by mastectomy. Therefore, the ultimate local control and survival rates were similar for all three modalities.

Adult↗
PubMed1995

Up to 50 X SAS performance gains on large data volumes using scalable parallel computing.

Turning large volumes of historical data into valuable information to support the decision making process of management is a growing need of corporations in the 90s. However, the ability to perform fast data reduction on large data volumes is limited by traditional computer systems that can take hours of CPU time and days of elapsed time to process multi-gigabyte data sets. This paper describes how one of my customers in the health care industry addressed the volume issue in health decision support processing and improved the end user's tool sets. The paper describes the problems encountered while trying to achieve their business goals and the hardware and software solution implemented to resolve these problems. Actual performance numbers are given for Tabulate, Select, 3-way Join, Nested Select Queries, and a multiple user test. With up to 50 X faster query turn-around times on large data volumes, productivity was increased by: 1) allowing users to extract valuable information with queries that could not be run before; 2) reducing the cost of data analysis; 3) providing users with more elaborate reporting and greater versatility due to SAS and the new client/server environment; and 4) improving overall business with more timely, accurate, and cost-effective results.

Computer Communication Networks↗
PubMed1994

The first human alpha-spectrin structural domain begins with serine.

The 106-amino acid sequence motifs of spectrin have been suggested to fold into stable structural domains, consisting mostly of coiled coils of triple helices. With the advent of molecular biology and biophysical techniques, structural studies of these spectrin 106-amino acid structural domains became approachable. However, one of the difficulties in such an approach is determination of the correct phasing of the structural domains, which may or may not coincide with the phasing of the sequence motifs. Proper identification of the domain phasing is vital to the construction of stable spectrin domains for molecular studies. A previously published phasing shift for Drosophila alpha-spectrin indicated a downstream phase-shift of 26 amino acids for the structural domain (Winograd, E., Hume, D., and Branton, D. (1991) Proc. Natl. Acad. Sci. U. S. A. 88, 10788-10791). Using this phase-shift, we prepared a recombinant spectrin peptide with the sequence from residue 49 to residue 155 of human erythrocyte alpha-spectrin and found this peptide to be unstable relative to other peptides that we prepared. Using several other recombinant alpha-spectrin peptides and following the protease digestion approach, we digested spectrin peptides with elastase and chymotrypsin and analyzed the amino acid sequence of the digestive products. We provide the first experimental evidence in identifying the first amino acid residue of the first spectrin domain in human erythrocyte alpha-spectrin as residue 52 (Ser).

Amino Acid Sequence↗
PubMed1994

Treatment of acute graft-versus-host disease with humanized anti-Tac: an antibody that binds to the interleukin-2 receptor.

Humanized anti-Tac is a genetically engineered human IgG1 monoclonal antibody specific for Tac, the alpha subunit of the interleukin-2 (IL-2) receptor, and blocks IL-2-dependent activation of human T lymphocytes. The safety, pharmacokinetics, and immunosuppressive activity of humanized anti-Tac were evaluated in 20 patients who developed acute graft-versus-host disease (GVHD) after allogeneic marrow transplantation. Patients had developed acute GVHD at 5 to 26 (median, 14) days after transplantation and had failed to respond to primary therapy with glucocorticoids. Sequential groups of 4 patients each received a single 1-hour infusion of antibody in escalating doses of 0.5, 1.0, or 1.5 mg/kg; 8 additional patients were then treated with 1.5 mg/kg. A second infusion of antibody was administered after 11 to 48 (median, 16) days in 8 patients who had transient improvement of GVHD after the first infusion. Acute side effects, limited to chills in 1 patient and diaphoresis in another, were observed during or shortly after the antibody infusion. Overall improvement of acute GVHD occurred in 8 patients, 6 of whom were treated with a single antibody infusion and 2 with two infusions. Four responses were complete and 4 were partial. Three additional patients had improvement in one organ but progression in another. Responses occurred in 9 of 16 cases with skin disease, 3 of 15 with liver disease, and 6 of 12 with gastrointestinal disease. Two patients survive at 529 and 645 days after antibody treatment. Two patients died after relapse of leukemia. Sixteen patients died of infection or organ failure between 5 and 211 (median, 55) days. The terminal elimination half-life of the antibody was 44 to 363 hours, with a harmonic mean of 79, 88, and 94 hours, respectively, for the three doses studied. Absolute peripheral blood T-lymphocyte counts remained unchanged during the 56 days after infusion of the antibody. A fraction of circulating T cells expressed the alpha chain of the IL-2 receptor that, in some patients, was bound by antibody in vivo up to 28 days after treatment. No patient developed a measurable antibody response to humanized anti-Tac. Humanized anti-Tac has a long half-life after intravenous injection in humans, superior to any rodent monoclonal antibody specific for human T cells, and does not appear to induce antibody formation in recipients of marrow transplants. Improvement of steroid-refractory GVHD in 40% of patients after only one or two antibody infusions indicates that humanized anti-Tac is immunosuppressive.

Adult↗
PubMed1994

Effectiveness of enalapril in combination with low-dose hydrochlorothiazide versus enalapril alone for mild to moderate systemic hypertension in black patients.

The importance of concomitant low-dose hydrochlorothiazide was assessed in black hypertensive patients treated with enalapril. Left ventricular (LV) mass and function, metabolic parameters, 24-hour ambulatory blood pressure (BP), exercise duration, and systolic BP response were evaluated before and after drug therapy. Enalapril 20 mg (group 1) or enalapril 20 mg plus hydrochlorothiazide 12.5 mg (single tablet; group 2) was given to 38 patients for 9 weeks in a double-blind, placebo-controlled, randomized study. LV mass measured 61 +/- 17 versus 102 +/- 23 g/m2, and 24-hour ambulatory BP measured 120 +/- 8/75 +/- 6 versus 155 +/- 12/100 +/- 6 mm Hg in matched control subjects (n = 40) versus hypertensive patients, respectively. No clinically important changes occurred in total cholesterol, serum uric acid or potassium in either group. Enalapril slightly reduced 24-hour ambulatory BP from 154 +/- 15/100 +/- 7 mm Hg to 148 +/- 19/96 +/- 11 mm Hg after treatment (p < 0.05 for systolic BP); systolic BP load (70% to 59%, p < 0.05), and diastolic BP load (67% to 60%, p = NS) decreased. Baseline BP decreased from 157 +/- 9/101 +/- 6 to 132 +/- 13/86 +/- 8 mm Hg (p < 0.0001); systolic BP load (64% to 29%, p < 0.0001), and diastolic BP load (64% to 33%, p < 0.0001) decreased in group 2. Exercise systolic BP was attenuated (p = 0.007, group 2; p = NS, group 1) and duration increased (p = NS) only in group 2.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Cardiovascular responses to standing: effect of hydration.

Many astronauts experience intolerance to orthostatic stress after space flight, despite the ingestion of salt tablets and water equivalent to 0.9% saline just before their return to Earth. Previous research indicates that the ingestion of 1.07% saline solution increased plasma volume more than did 0.9% saline. Therefore, the authors hypothesized that the 1.07% saline would be more effective in reducing orthostatic stress during standing. In this study, six men (22-47 years) performed a 5-minute "stand test" (5 minutes supine followed by 5 minutes standing) under four hydration conditions: 1) hypohydrated (HYPO, 20 mg intravenous [IV] Lasix), 2) euhydrated (EU), 3) rehydrated with 1 L 0.9% saline 2 hours after Lasix, or 4) rehydrated with 1 L 1.07% saline. Stand tests were done 4 5 hours after rehydration. Plasma volume was reduced 10% after Lasix, and was restored by both rehydration solutions. When subjects stood, their diastolic pressure, mean pressure, heart rate (HR), and peripheral resistance increased (P < .05), and their stroke volume (SV), cardiac output (CO), and thoracic fluid (TF, by impedance cardiography) decreased (P < .05). Systolic arterial pressure (SBP) increased when subjects stood after saline, but decreased if subjects were HYPO or EU (P < .05 for 1.07% versus HYPO and EU). Heart rate (HR), another indicator of orthostatic stress, did not differ among hydration states. During the last minute of the stand test, TF was greater if subjects had fluid countermeasures. Stroke volume, CO, and TF were significantly less during minute 5 of standing than during minute 3. Whether they would continue to fall in a longer stand test is not known. The results for SBP indicate that 1.07% saline may have advantages over 0.9% saline as a countermeasure to postspace-flight or postbedrest orthostatic intolerance.

Adult↗
PubMed1994

Quantification of functional deficit in Alzheimer's disease using a computer-assisted mapping program for 99mTc-HMPAO SPECT.

A computer-assisted mapping program was developed to determine changes of cerebral perfusion in normal and pathological aging using single photon emission computer tomography (SPECT) and 99mTc-hexamethylpropyleneamine oxime (HMPAO). The software program outlined the cortex on 14 adjacent brain slices, and superimposed a ring of 12 regions of interest on each slice. Regional/global and regional/cerebellar relative flow values were calculated in 27 patients with clinically diagnosed Alzheimer's disease (AD) (mean age 71 years, SD 7.6) and in 10 normal controls (mean age 73.7 years, SD 7.3). The Dementia Rating Scale (DRS) was used to assess mental status in all subjects. Multiple regression analysis demonstrated a significant correlation between relative flow values and the DRS score. Regional/cerebellar (R = 0.88, p < 0.0001) relative flow values were a better indicator of cortical impairment than regional/global relative flow values (R = 0.68, p = 0.003). Of the brain regions of interest, the left parietal flow values correlated best with the DRS score (r = 0.83, p < 0.0001), a cutoff value of 77 accurately classifying 80% of the normals and 100% of the patients diagnosed as having Alzheimer's disease. The data show that computer-assisted mapping of SPECT can provide semiquantitative flow values with high diagnostic accuracy.

Aged↗