Search PubMed⌕ Search

Biomedical subjects

J White

Publications and source records attributed to J White.

At least 343 records · Page 19Linked to original sources
PubMed1994

Custom shoe therapy. Current concepts, designs, and special considerations.

Custom orthopedic shoes represent the ultimate combination of function and aesthetics. Incorporating biomechanics and craftsmanship, shoes can redistribute weight, restrict joint motion, facilitate ambulation, and decrease the probability of neuropathic ulceration. Despite these advantages, many podiatrists know little about shoe therapy and consequently underuse it. This article describes the various types of therapeutic shoe modalities available and presents a systematic method of their application. Some of the latest developments in technology and health care reform also are revealed.

Equipment Design↗
PubMed1993

The patterns of binding of RAR, RXR and TR homo- and heterodimers to direct repeats are dictated by the binding specificites of the DNA binding domains.

We show here that, in addition to generating an increase in DNA binding efficiency, heterodimerization of retinoid X receptor (RXR) with either retinoic acid receptor (RAR) or thyroid hormone receptor (TR) alters the binding site repertoires of RAR, RXR and TR homodimers. The binding site specificities of both homo- and heterodimers appear to be largely determined by their DNA binding domains (DBDs), and are dictated by (i) homocooperative DNA binding of the RXR DBD, (ii) heterocooperative DNA binding of RXR/RAR and RXR/TR DBDs, and (iii) steric hindrance. No homodimerization domain exists in the DBDs of TR and RAR. The dimerization function which is located in the ligand binding domain further stabilizes, but in general does not change, the repertoire dictated by the corresponding DBD(s). The binding repertoire can be further modified by the actual sequence of the binding site. We also provide evidence supporting the view that the cooperative binding of the RXR/RAR and RXR/TR DBDs to directly repeated elements is anisotropic, with interactions between the dimerization interfaces occurring only with RXR bound to the 5' located motif. This polarity, which appears to be maintained in the full-length receptor heterodimers, may constitute a novel parameter in promoter-specific transactivation.

Amino Acid Sequence↗
PubMed1993

The use of iodine-125 seeds as a substitute for iridium-192 seeds in temporary interstitial breast implants.

PURPOSE: We have previously reported that the use of iodine-125 seeds in temporary plastic tube interstitial implants may be more advantageous than iridium-192 seeds due to less patient and personnel radiation exposure, reduced shielding requirements, and significant dosimetric advantages. The impact of this isotope on the rate of local control and cosmetic outcome in patients with early stage breast cancer treated with interstitial implants for their irradiation "boost" remains to be defined. METHODS AND MATERIALS: We reviewed the treatment outcome of 402 consecutive cases of Stage I and II breast cancer undergoing breast conserving therapy between 1/1/80 and 12/31/87. All patients underwent excisional biopsy and received 45-50 Gy to the entire breast followed by a boost to the tumor bed using either electrons (104 patients), photons (15 patients), or an interstitial implant with either iridium-192 (197 patients) or iodine-125 (86 patients) to at least 60 Gy. Iodine-125 implants were primarily performed in patients with significant risk factors for local recurrence (71%) or in patients with large breasts (17%). Local tumor control and cosmetic outcome were assessed and contrasted between patients boosted with each modality. RESULTS: With a median follow-up of 59.3 months, 18 (4.5%) patients developed a recurrence of the tumor in the treated breast (4.4% 5-year actuarial rate). No statistically significant differences in the 5-year actuarial rate of local recurrence were noted between patients boosted with either iodine-125 (3.0%), iridium-192 (3.8%), electrons (5.4%), or photons (0%). Likewise, no significant differences in the percentage of patients obtaining good/excellent cosmetic results were noted between iodine-125 (93%), iridium-192 (88%), electrons (90%), or photons (82%). CONCLUSION: We conclude that patients with Stage I and II breast cancer undergoing breast conserving therapy and judged to be candidates for boosts with interstitial implants can be effectively treated with iodine-125 seeds. Use of this isotope results in less patient and personnel irradiation exposure and a better dose distribution than iridium-192, since dose optimization can be routinely employed. Overall, local control and cosmetic outcome have been excellent and are similar to either iridium-192, electrons, or photons.

Brachytherapy↗
PubMed1993

Antigen recognition properties of mutant V beta 3+ T cell receptors are consistent with an immunoglobulin-like structure for the receptor.

We examined the effect of mutations in the V beta portion of a pigeon cytochrome c (cyto c)-specific V beta 3+/V alpha 11+ T cell receptor on its ability to recognize cyto c/IEk and various superantigens. The results were consistent with an immunoglobulin-like structure for the receptor V beta domain and with separate interaction sites on V beta for conventional antigen and superantigens. An amino acid predicted to lie in CDR1 was critical for cyto c/IEk but not superantigen recognition, while several amino acids predicted to lie in the hypervariable region 4 loop were critical for superantigen but not cyto c/IEk recognition.

Amino Acid Sequence↗
PubMed1993

Safety, success, and restenosis after elective coronary implantation of the Palmaz-Schatz stent in 100 patients at a single center.

We report the immediate safety, efficacy, and 6-month angiographic follow-up after elective implantation of the Palmaz-Schatz stent (Johnson & Johnson Interventional Systems, Warren, N.J.) in the first 100 consecutive patients at a single center. Patients with suitable cardiac anatomy and no contraindications to anticoagulation were prospectively entered into the study. One hundred two stents were successfully implanted in 99 patients. The mean diameter stenosis was 70% +/- 11% before implantation and was reduced to 20% +/- 11% after stent implantation. There were no deaths, Q-wave myocardial infarcts, urgent bypass operations, or strokes during the procedure or follow-up period. Stent thrombosis occurred in two patients; in both vessel patency was successfully accomplished by balloon angioplasty. There were three gastrointestinal hemorrhages, two of which required transfusion. Angiographic follow-up was performed in 98% of patients at 6.3 +/- 2.6 months after the procedure. Restenosis (> or = 50% stenosis within or immediately adjacent to the stent) occurred in 32%. Stent restenosis was associated with male sex (36% vs 7% for female subjects; p = 0.03) and stent implantation in a restenosis lesion (47% vs 25% for de novo lesions; p = 0.03); it was inversely associated with current cigarette smoking (0% vs 36% for nonsmokers; p = 0.02). In conclusion, the Palmaz-Schatz stent can be electively implanted with high success and low complication rates. The restenosis rate appears to be similar to that of balloon angioplasty.

Angina Pectoris↗
PubMed1993

Spectral analysis and modelling of ACh and NE effects on shark nervus terminalis activity.

We investigated the effects of acetylcholine (ACh) and norepinephrine (NE) on activity in the nervus terminalis (NT) ganglion of the bonnethead shark (Sphyrna tiburo) using an in vitro preparation and whole nerve recordings. Spectral analysis indicated that ACh (10 and 100 microM) had a variable effect on the total spectral power of whole nerve activity but produced a consistent decrease in half power frequency (HPF; the median frequency of the power spectrum). Norepinephrine (10 microM) reduced baseline activity and total spectral power but produced an increase in HPF in all NT preparations. Computer simulations of extracellular recordings suggested a general explanation for these findings. Acetylcholine may have opposite effects on activity in two NT cell populations with axons in the central nerve trunk, increasing activity in cells whose axons have broad spikes (low spectral frequency) and decreasing activity in cells whose axons have narrow spikes (high spectral frequency). The NE effects are consistent with a decrease in activity of cells whose axons have broad spikes (low spectral frequency) and little or no change in cells whose axons have narrow spikes (high spectral frequency). The physiological data, together with the theoretical analysis, suggest that cholinergic and catecholaminergic neurotransmitter systems are active in the bonnethead NT ganglion, and that ACh and NE have different effects on two populations of ganglion cells.

Acetylcholine↗
PubMed1993

A novel thiadiazinone derivative fully reverses acidosis-induced depression of force in cardiac muscle by a calcium-sensitizing effect.

1. We examined the effects of the novel thiadiazinone derivative EMD 57033 on developed force and intracellular [Ca2+] in cardiac muscle during control conditions (pH 7.35) and in acidosis (pH 6.8). 2. In the control solution, application of EMD 57033 fully activated the muscle. Acidosis reduced developed force to 18% of maximum, but application of EMD 57033 in acid solution was able to fully reverse this effect and restore force to its previous maximum. 3. During the positive inotropic effect in acidosis, the Ca2+ transients declined to 62% of their initial amplitude, whereas force increased to 557%. 4. These observations suggest that EMD 57033 increases force by a Ca(2+)-sensitizing action in intact cardiac muscle. Since EMD 57033 is able to fully reverse the effects of acidosis on force without increasing the amplitude of the Ca2+ transients, this compound and others with similar mechanisms of action appear to hold particular promise for heart failure therapy.

Acidosis↗
PubMed1993

Haemoglobin, ferritin, and iron intakes in British children aged 12-14 years: a preliminary investigation.

The purpose of the study was to assess the prevalence of Fe deficiency and Fe-deficiency anaemia in a group of apparently healthy adolescents, and to assess the value of a food frequency and amount questionnaire as a screening tool to identify children at risk of Fe deficiency. White schoolchildren (399) aged 12-14 years living in a Southwest London suburb completed a food frequency and amount questionnaire to assess usual Fe and vitamin C intake, and provided a thumb-prick blood sample for analysis of haemoglobin (Hb), packed cell volume (PCV), and serum ferritin (SF). Children were classified as 'anaemic' if Hb was below the Dallman 3rd percentile (girls: < 120 g/l; boys: < 122, < 124 and < 126 g/l at ages 12, 13 and 14 years respectively); and 'low' or 'borderline' in Fe stores if SF was < 12 micrograms/l, or between 12 and 20 micrograms/l respectively. Of the boys and girls 3.5 and 10.5% respectively were anaemic; 1% of boys and 4% of girls had low ferritin values, and 14% of boys and 16% of girls were borderline. Fe intakes were significantly higher in boys than in girls (12.3 v. 9.6 mg/d, P < 0.001). Prevalence of anaemia was 14.5% in the group with both low Fe intakes (< lower reference nutrient intake) and low vitamin C intakes (< median), compared with 2.3% in the group with both high Fe intakes (> reference nutrient intake) and high vitamin C intakes (> median).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Non-traffic child pedestrian injuries.

All non-traffic child pedestrian deaths and injuries resulting in hospitalization in the Auckland region over a 5 year period were identified from coroner's and hospital records. There were eight deaths (0.77/100,000 children per year) and 91 hospital admissions (8.7/100,000 children per year). Close to half (48%) of the non-traffic pedestrian injury admissions had been misclassified as traffic pedestrian injuries. Eighty-seven per cent of the non-traffic pedestrian injury deaths and 93% of the injuries occurred in residential driveways, most often involving a child run over by a reversing vehicle. Further studies are required to determine the most effective strategies for the prevention of non-traffic child pedestrian injuries.

Accidents↗
PubMed1993

The bacterial and mouse mammary tumor virus superantigens; two different families of proteins with the same functions.

In conclusion, the bacterial toxins are completely unlike the MTV superantigens in primary sequence and structure. The former are soluble globular proteins which do not have to be proteolytically cleaved before they act. The latter are synthesized as type II membrane proteins and may be clipped before they reach the cell surface and act to stimulate T cells. Table III summarizes the similarities and differences between the two sets of superantigens. The most notable quality of these molecules is that both sets of families have developed strategies whereby they bind to Class II and engage V beta. As far as the microorganisms which produce them are concerned, these two properties appear to be essential since they are absolutely conserved over proteins of a number of different structures. Several questions can now be addressed as follows. a. Why do all known superantigens bind to Class II? For the microorganism which produces them, the function of superantigens appears to be T-cell and perhaps directly or indirectly B-cell and macrophage stimulation. Activation of virgin T cells requires engagement with antigen plus MHC on professional antigen-presenting cells. Unlike other cell surface proteins, for example Class I, most Class II in animals is expressed on such cells. Therefore it is likely that superantigens have evolved to engage Class II because presentation to T cells by Class II-bearing cells offers the superantigen the best chance of activating its target T cells. b. Why do superantigens engage TCR V beta and not V alpha or CD3? It is possible that superantigens bind to the V beta portion of the TCR rather than V alpha because the latter does not have a consistently well exposed face for engagement. The fact that it is perhaps relatively easier to produce anti-V beta rather than anti-V alpha antibodies supports this idea. We have shown that N-glycosylation of V beta can interfere with recognition by vSAGs (Pullen et al. 1991), perhaps glycosylation of V alpha tends to conceal otherwise available sites. As far as C beta, C alpha or CD3 engagement is concerned, this may be just too dangerous for MTVs. The role of MTVs SAgs in the life history of the virus seems to be to stimulate T cells in the suckling recipient and thereby create a pool of activated lymphocytes in which the virus may survive until the mouse gives birth and transmits the virus to her own progeny (Hainaut et al. 1990, Golovkina et al. 1992).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗