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Biomedical subjects

J Black

Publications and source records attributed to J Black.

At least 109 records · Page 6Linked to original sources
PubMed1997

Effects of particles on fibroblast proliferation and bone resorption in vitro.

An in vitro study was conducted to determine the ability of particle challenged human peripheral monocytes to modulate fibroblast proliferation and bone resorption. The effects of commercially pure titanium, titanium-aluminum-vanadium, and ultrahigh molecular weight polyethylene wear debris, either fabricated or retrieved from patients with failed total hip arthroplasties, were examined as a function of the composition, size, and dose of particles. In vitro generated particles were selected to be matched closely in particle size distribution to that found in vivo. Dosages were controlled by standardizing the ratio of particle surface area to mean monocyte surface area. The results support the hypothesis that, in vitro, challenge of monocytes by particulate wear debris results in a biphasic dose response. For the metal particles, fibrogenesis was observed over the range of 1x to 10x surface area ratio (the surface area of particles to the surface area of cells), although for metallic and polyethylene particles, saturated doses of 10x surface area ratio were required to stimulate bone resorption. In addition, metallic particles were able to stimulate fibrogenesis at doses at which simulated and retrieved polyethylene were ineffective. Although there may be a nonosteolytic chronically tolerable annual dose of ultrahigh molecular weight polyethylene wear debris corresponding to approximately 1x surface area ratio, lower doses, especially of metallic debris, may produce reactive fibroblast proliferation and fibroplasia that may contribute to implant loosening and failure.

Adult↗
PubMed1997

HLA DQB1*0602 is associated with cataplexy in 509 narcoleptic patients.

Narcolepsy is a sleep disorder associated with HLA DR15 (DR2) and DQB1*0602. We HLA typed 509 patients enrolled in a clinical trial for the drug modafinil and analyzed the results in relation to cataplexy, a symptom of narcolepsy characterized by muscle weakness triggered by emotions. The patients were either subjects with cataplexy who had a mean sleep latency (SL) of less than 8 minutes and two or more sleep onset rapid eye movement (REM) periods (SOREMPs) during a multiple sleep latency test, or narcoleptic patients without cataplexy but with a mean SL shorter than 5 minutes and two or more SOREMPs. The respective values of DRB1*15 (DR2) and DQB1*0602 as markers for narcolepsy were first compared in different ethnic groups and in patients with and without cataplexy. DQB1*0602 was found to be a more sensitive marker for narcolepsy than DRB1*15 across all ethnic groups. DQB1*0602 frequency was strikingly higher in patients with cataplexy versus patients without cataplexy (76.1% in 421 patients versus 40.9% in 88 patients). Positivity was highest in patients with severe cataplexy (94.8%) and progressively decreased to 54.2% in patients with the mildest cataplexy. A voluntary 50-item questionnaire focusing on cataplexy was also analyzed in 212 of the 509 HLA-typed patients. Subjects with definite cataplexy as observed by an experienced clinician were more frequently HLA DQB1*0602-positive than those with doubtful cataplexy, and the manifestations of cataplexy were clinically more typical in DQB1*0602-positive patients. These results show that the HLA association is as tight as previously reported (85-95%) when cataplexy is clinically typical or severe. We also found that patients with mild, atypical, or no cataplexy have a significantly increased DQB1*0602 frequency (40-60%) in comparison with ethnically matched controls (24%). These results could be explained by increased disease heterogeneity in the noncataplexy group or by a direct effect of the HLA DQB1*0602 genotype on the clinical expression of narcolepsy.

Adolescent↗
PubMed1996

Outlook for survivors of childhood in sub-Saharan Africa: adult mortality in Tanzania. Adult Morbidity and Mortality Project.

OBJECTIVE: To measure age and sex specific mortality in adults (15-59 years) in one urban and two rural areas of Tanzania. DESIGN: Reporting of all deaths occurring between 1 June 1992 and 31 May 1995. SETTING: Eight branches in Dar es Salaam (Tanzania's largest city), 59 villages in Morogoro rural district (a poor rural area), and 47 villages in Hai district (a more prosperous rural area). SUBJECTS: 40,304 adults in Dar es Salaam, 69,964 in Hai, 50,465 in Morogoro rural. MAIN OUTCOME MEASURES: Mortality and probability of death between 15 and 59 years of age (45Q15). RESULTS: During the three year observation period a total of 4929 deaths were recorded in adults aged 15-59 years in all areas. Crude mortalities ranged from 6.1/1000/year for women in Hai to 15.9/1000/year for men in Morogoro rural. Age specific mortalities were up to 43 times higher than rates in England and Wales. Rates were higher in men at all ages in the two rural areas except in the age group 25 to 29 years in Hai and 20 to 34 years in Morogoro rural. In Dar es Salaam rates in men were higher only in the 40 to 59 year age group. The probability of death before age 60 of a 15 year old man (45Q15) was 47% in Dar es Salaam, 37% in Hai, and 58% in Morogoro; for women these figures were 45%, 26%, and 48%, respectively. (The average 45Q15s for men and women in established market economies are 15% and 7%, respectively.) CONCLUSION: Survivors of childhood in Tanzania continue to show high rates of mortality throughout adult life. As the health of adults is essential for the wellbeing of young and old there is an urgent need to develop policies that deal with the causes of adult mortality.

Adolescent↗
PubMed1996

Human monocyte morphology is affected by local substrate charge heterogeneity.

Cells are sensitive to topological, chemical, and electrical properties of substrates on which they are grown. However, most studies of cell-surface interactions have neglected electrical effects or confounded them with other substrate properties. The use of nanofabrication technology has made it possible to fabricate optically transparent surfaces with controlled chemistry and topology, and with active, controllable surface charge density in domains as small as 1-4 microns. Human monocytes incubated on polystyrene with 3.3 microns-wide strip domains, alternately charged so as to maintain overall charge neutrality, show significant charge density and time-dependent increases (greater than twofold) in cell area and cell perimeter after challenge with a phagocytic trigger (human IgG opsonized zymosan particles). Additional utlrastructural studies on silicon dioxide substrates show charge-density-dependent qualitative morphological differences. These studies clearly demonstrate that human monocytes respond in vitro to local surface-charge heterogeneity in the absence of substrate topology and compositional variation.

Biocompatible Materials↗
PubMed1996

Carcinogenicity of CoCrMo (F-75) implants in the rat.

A long-term study was conducted in rats to assess the contribution of the surface area of CoCrMo devices to carcinogenesis. Groups consisting of 104 rats each (52 male, 52 female) were either implanted with metal cylinders fixed on the left, lateral femur (groups 1-3) or injected with a suspension of metal microspheres in the dorsal subcutis (group 4). Group 1 (control) received solid Ti6Al4V cylinders [surface area to body weight (SA/BW) ratio measuring 1.35 times that of human total hip prosthesis (HTHP)]. Group 2 was implanted with solid CoCrMo (SA/BW ratio: identical to implants of group 1). Group 3 received sintered-porous CoCrMo devices (SA/BW ratio: 30 x HTHP). Group 4 was injected with a suspension of CoCrMO microspheres (SA/BW ratio: 135 x HTHP). Implant-associated tumors (IATs) were observed in 23, 14, 3, and 15 rats of groups 1, 2, 3, and 4, respectively. Within groups 1 and 2, 34 IATs were associated with loose implants, three with undetermined implant fixation status, and none with fixed implants. A significantly increased accumulation of chronic inflammatory tissues around loose rather than fixed implants suggested a foreign-body reaction as the primary mechanism of carcinogenesis. A secondary role in carcinogenesis was ascribed to the increased CoCrMo implant SA/BW ratios as indicated by a 14.6% IAT incidence in group 4 versus 3% in group 3. These results support the notion that early intervention in the removal of loose metal devices is warranted to mitigate against foreign body-induced carcinogenesis, at least in this animal model.

Animals↗
PubMed1996

In vivo wear of Ti6A14V femoral heads: a retrieval study.

The surface characteristics of sixteen "monobloc" titanium-6% aluminum-4% vanadium (Ti6A14V) femoral components (two of the 6-Ti-28 type and 14 of the 6-Ti-32 type) retrieved after periods of 78-131 months following loosening of the femoral component, as well as two unimplanted controls, were studied. The femoral heads were examined by a combination of noncontact light profilometry, scanning electron microscopy, and energy-dispersive X-ray analysis. No consistent correlations were found between classical surface roughness parameters (average, root mean square, peak-to-valley roughness, and radius of curvature) and any clinical parameter studied (patient gender, weight, and height; primary diagnosis; implantation time; or calculated force applied on the hip joint). This extensive quantitative topographic analysis suggests that wear mechanisms in vivo are complex and that wear of titanium alloy femoral heads is partly attributed to a combination of an imperfect nature of the surface before implantation, removal of the oxide layer causing abrasion of the alloy, subsequent deformation of the bearing surface including polishing, and, to a very small degree, patient parameters.

Aged↗
PubMed1996

A patient dose survey for femoral arteriogram diagnostic radiographic examinations using a dose-area product meter.

We present a method for dealing with a complex radiographic procedure (which involves multiple radiographs and fluoroscopy) in an attempt to provide a simple way of calculating effective dose from which a general risk factor can be determined. A useful index of harm can be obtained by recording the number of radiographs in each region, and the fluoroscopy time, from which the effective dose may be easily calculated. A patient dose survey was carried out using a PTW diamentor for femoral arteriogram procedures in a large teaching hospital. The procedure involves fluoroscopy to the pelvic region to locate a guide wire and catheter, followed by a series of radiographs extending from the pelvic area to the feet to form a collage image of the entire arterial system. Radiographs are taken whilst a bolus of contrast media is injected into the arterial system. These measurements extend a continuing survey of doses for common diagnostic radiographic examinations which have previously included the simple examinations of lumbar spine, abdomen and pelvis.

Aged↗
PubMed1996

Neurotoxicity, anticoagulant activity and evidence of rhabdomyolysis in patients bitten by death adders (Acanthophis sp.) in southern Papua New Guinea.

Thirty-two patients with enzyme-immunoassay-proven death adder (Acanthophis sp.) bites were studied in Port Moresby, Papua New Guinea. Eighteen were envenomed; local signs were rare and none had incoagulable blood, but all except one had signs of neurotoxicity. Five (27.7%) envenomed patients required intubation and ventilation. One patient developed renal failure, previously undescribed following death adder bites. Laboratory investigations showed mild prolongation of prothrombin and partial thromboplastin times in some patients. In vitro studies showed that the venom contains anticoagulant activity, but does not cause fibrinogenolysis. In contrast to taipan envenoming, neurotoxicity did not progress after antivenom administration, and there was reversal of neurotoxicity, evident within 6 h, in three severely envenomed patients treated less than 12 h after the bite. One patient treated with antivenom and anticholinesterases had the most dramatic response to treatment; the optimum management of bites by this species may include prompt treatment with both antivenom and anticholinesterases in addition to effective first aid.

Adolescent↗
PubMed1996

Cobalt and chromium concentrations in patients with metal on metal total hip replacements.

There has been a resurgence of interest in the use of metal on metal bearings in total hip arthroplasty. Although the use of metal on metal bearing couples would eliminate or substantially reduce particulate polyethylene generation (depending on the presence or absence of polyethylene in the implant system), there is concern about the potential for increased particulate and ionic metal generation in comparison with polyethylene on metal bearings. These metallic degradation products may be transported away from the implant site and distributed systemically. Chromium concentrations in the serum and urine and cobalt concentrations in the serum were measured in subjects with cobalt chromium alloy metal on metal total hip replacements and in controls without implants. Eight subjects with long term (> 20 years) McKee-Farrar total hip replacements had 9-fold elevations in serum chromium, 35-fold elevations in urine chromium, and at least 3-fold elevations in serum cobalt concentrations in comparison with controls. Six subjects with short term (< 2 years) metal on metal surface replacement arthroplasties had 3-fold elevations in serum chromium, 4-fold elevations in urine chromium, and 4-fold elevations in serum cobalt concentrations in comparison with subjects with McKee-Farrar implants. Although the toxicologic importance of these trace metal elevations has not been established, serum and urine metal concentrations may be useful markers for the tribologic performance of metal on metal bearings.

Adult↗
PubMed1996

Dogbites in children.

The incidence of dogbite injuries in children has risen steadily in the United States in the past several years. Plastic surgical nurses should familiarize themselves, with the initial care, surgical repair, complications of dog bites, emotional care, and discharge instructions so that children can be provided optimal care.

Animals↗
PubMed1996

Writing for publication: advice to potential authors.

If you have thought about writing for publication, then take the time to read this article! Plastic Surgical Nursing Editor Joyce Black, MSN, RNC, CPSN, will discuss each step of the process, including tips on generating a topic, writing the first draft, editing your work, and submitting to a journal. Advice to authors on submitting to Plastic Surgical Nursing will also be discussed.

Humans↗
PubMed1996

Ultrasonography of breast hamartomas.

The authors present the breast ultrasound findings of nine women with mammographic abnormalities typical of breast hamartomas. Two of the mammographically detected hamartomas could not be identified at breast ultrasound. Six hamartomas were well-circumscribed masses of heterogeneous echogenicity with no posterior acoustic shadowing. One lesion was a well-defined hypo-echoic mass with no posterior shadowing. We conclude that many mammographically and clinically detected hamartomas can be clearly identified at breast ultrasound. The breast sonographer should be aware of the spectrum of appearances that may occur. When a breast abnormality has the characteristic mammographic appearances of a hamartoma, it may be counterproductive to perform an additional breast ultrasound.

Adult↗
PubMed1996

A personal view of pharmacology.

This essay is an account of the author's experience in trying to interpret the action of drugs as seen in in vitro bioassays. The central theme is how the development of simple mathematical models has assisted in the interpretation of drug actions. Starting from encounters with partial agonists, the essay describes the development of an operational model of agonist activity, the significance of receptor distribution, the analysis of indirect competitive antagonism and various two-receptor systems, followed by examples of pharmacological resultant activity. Analyses of tissue and species variations are described. The essay ends with an assessment of the future of bioassay in pharmacology.

Animals↗
PubMed1996

The acute phase response to cardiopulmonary bypass in children.

The endocrine phase of the stress response to cardiopulmonary bypass in children is known to be subtly different from that seen in adults. The aim of this investigation was to determine whether there are similar differences in the acute phase response. Thirteen children were studied (mean age 2.65 years). Each child had congenital heart disease and underwent corrective cardiac surgery. Blood samples taken two days prior to operation and at 6, 9, 12, 24, 48 and 120 hours after were analysed for C-reactive protein, albumin, caeruloplasmin, zinc and copper concentrations. Metal:carrier protein molar ratios were also calculated. Results demonstrate changes which, although similar to those seen in adults, differed both quantitatively and qualitatively. This is explained by the concept of immaturity leading to a generally poor capacity for protein synthesis and a relative inability to respond to altered circumstances.

Acute-Phase Reaction↗
PubMed1996

Severe and complicated falciparum malaria in Melanesian adults in Papua New Guinea.

Severe falciparum malaria usually occurs in children, but also occurs in nonimmune migrants or partially immune adults in areas of unstable transmission. We have studied prospectively 70 adult patients with strictly defined severe malaria from the south coast of Papua New Guinea where malaria transmission is not intense. Only 19 (27.1%) were migrants from areas where malaria transmission does not occur; many other patients were periurban dwellers who had become infected after visits to their home villages. The most common clinical features were jaundice or hepatic dysfunction, impaired consciousness, renal failure, cerebral malaria, and anemia. Hypoglycemia was common following treatment with quinine. The overall case fatality rate was 18.6%; renal failure and cerebral malaria in particular were associated with a poor outcome. Reduction in mortality might be achieved by aggressive therapy of renal failure with earlier institution of dialysis; the use of preventive measures for immigrants or urban dwellers returning to high transmission areas might reduce the incidence of this dangerous disease.

Adolescent↗