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Biomedical subjects

D Wallace

Publications and source records attributed to D Wallace.

At least 109 records · Page 6Linked to original sources
PubMed1994

Quantitative and qualitative analysis of polyethylene wear particles in synovial fluid of patients with total knee arthroplasty. A preliminary report.

Synovial fluid from 13 knees undergoing revision total knee arthroplasty was subjected to chemical digestion and ultrafiltration. Scanning electron microscopy was used to visualize high-density polyethylene particles filtered from the fluid, and the images were analyzed using digital imaging software. This data were correlated with polyethylene wear patterns seen at the time of revision surgery. Patients' prostheses with gross polyethylene wear were differentiated from those with surface deformation and burnishing. The knees had been in situ for periods ranging from 3 to 112 months, and included 6 different prosthetic designs. The average area of the polyethylene particles measured ranged from 41 to 701 mu 2, and the total number of particles identified for each sample ranged from 38 to 279 mu 2. The largest particle identified had a surface area of 17,500 mu 2. Using the fluid volume analyzed, the particle area per milliliter of synovial fluid examined was calculated, and values ranged from 6.22 x 10(4) to 2.06 x 10(6) mu 2/ml. Visualization of high-density polyethylene using scanning electron microscopy allows greater resolution of morphologic detail than is possible with routine histologic examination using light microscopy. There were trends toward increasing particle size and total particle area in patients with gross polyethylene wear. The area of high-density polyethylene per milliliter of fluid in patients with gross wear was found to be statistically greater than that of patients without gross wear (p = 0.047). This technique offers a potentially valuable method of evaluating the status of high-density-polyethylene bearing surfaces in situ using a noninvasive technique.

Aged↗
PubMed1993

The coming crisis of public health in the suburbs.

A process of urban decay, coupled with forced displacement and behavioral problems, affecting an increasing number of neighborhoods in large U.S. cities. The resulting social disintegration has intensified a nexus of deviant behaviors and conditions, including substance abuse, that are related to transmission of HIV and resurgence of other contagious diseases. These diseases will diffuse, or are already diffusing, along the transportation hierarchy from larger into smaller central cities, and radially from the central cities into the surrounding areas. A widespread program of urban reform is a critical precondition for the control of contagious disease in the United States. It also is important for housing, social services, housing-related public services, and public health across urban and suburban jurisdictions.

Communicable Disease Control↗
PubMed1992

A history of the Lunatic Reception House, Darlinghurst.

The Lunatic Reception House at Darlinghurst operated between 1868 and 1961. Established to remove the stigma of criminality from the care of the insane, it operated as an observation ward and was for most of its time the sole portal of entry into metropolitan psychiatric hospitals in Sydney. An account of its inception and notable aspects of its history, with particular reference to lunacy legislation, is presented.

Commitment of Persons with Psychiatric Disorders↗
PubMed1992

Comparative biodisposition and metabolism of 14C-(+/-)-fenfluramine in mouse, rat, dog and man.

1. The comparative metabolism of fenfluramine was investigated in mouse, rat, dog and man following a single oral dose of 14C-(+/-)-fenfluramine hydrochloride (1 mg/kg), and also in rat after eight consecutive 12-h subcutaneous doses (24 mg/kg). 2. Main route of excretion of radioactivity in all species and at all doses was into urine (> 80%), with only minor amounts of radioactivity found in faeces. 3. From all species examined a total of 11 metabolites were observed in urine and plasma by t.l.c. and h.p.l.c. analysis and no metabolite was present in the plasma which was not present in urine. 4. All species dealkylate fenfluramine to the active metabolite norfenfluramine, to a relative greater or lesser extent, with plasma metabolic ratios (norfenfluramine/fenfluramine) showing inter-animal variation (rat >> dog >> mouse = man). 5. These differences are due to the efficient deamination of both compounds to polar inactive metabolites in man, with less dealkylation and lower plasma levels of norfenfluramine compared with the other species studied. 6. In conclusion, major species differences in the metabolism of (+/-)-fenfluramine, both qualitative and quantitative were observed, and no one species had a similar metabolic profile to that found in man.

Animals↗
PubMed1992

Transnasal stereotactic biopsy of a clivus tumor. Technical note.

Computerized tomography-guided transnasal stereotactic tissue diagnosis of a lytic lesion in the clivus was performed successfully using the Cosman-Roberts-Wells frame, thus avoiding a major craniotomy. The authors recommend stereotaxis as the preferred technique for biopsy in this region.

Biopsy↗
PubMed1991

Study of human urinary metabolism of fenfluramine using gas chromatography-mass spectrometry.

The metabolism of (+/-)fenfluramine, 1-(m-trifluoromethylphenyl)-2-N-ethylpropane, an anoretic agent, was investigated in humans. The analysis method was based on the use of ion-exchange resin extraction, solid-phase purification on the Bond Elut1M C8 cartridge, gradient elution high-performance liquid chromatography, enzymic hydrolysis of conjugates, further purification by Bond Elut C8 cartridge, derivatisation and capillary column gas chromatography-mass spectrometry (GC-MS). After administration of a 1 mg kg-1 oral dose, four metabolites plus unchanged fenfluramine were recovered in the 0-24 h urine from human volunteers and characterised by GC-MS. In the conjugated form, fenfluramine, norfenfluramine and m-trifluoromethylhippuric acid were detected by GC-MS. In the aglycone form, the major metabolite, 1-(m-trifluoromethylphenyl)-1,2-propane diol (fenfluramine diol), was monitored using GC-MS. The mass spectral characteristics of the m-trifluoromethylhippuric acid methyl ester, 1-(m-trifluoromethylphenyl)-1,2-propane ditrifluoracetate derivatives and the norfenfluramine and fenfluramine free base obtained under electron-impact ionization are presented. The metabolism of fenfluramine is discussed including a metabolic pathway in man accounting for the formation of its biotransformation products.

Biotransformation↗
PubMed1991

HIV-2 infection in an American.

HIV-2 is endemic in West Africa but rare elsewhere. In the USA there have been 18 reported cases of HIV-2 infection; most identified people have been West Africans. We recently diagnosed the first case of HIV-2 infection in a native-born US citizen, a woman whose serum was found to be reactive to anti-HIV-1 enzyme immunoassay (EIA) when she attempted to donate blood in 1986. Although both HIV-1- and HIV-2-specific EIAs were reactive, the anti-HIV-2 Western blot (WB) was positive, while the anti-HIV-1 WB was positive or indeterminate on different occasions. Synthetic peptide testing was reactive for HIV-2 but not HIV-1. HIV-2 DNA was detected using the polymerase chain reaction procedure. Although she had travelled to West Africa, it is unclear how she became infected with HIV-2.

Adult↗
PubMed1991

Meningitis caused by Psychrobacter immobilis in an infant.

Psychrobacter immobilis was isolated from the cerebrospinal fluid (CSF) and blood of a 2-day-old infant who appeared well except for a fever and a full anterior fontanelle. The infant was treated with antibiotics intravenously. After 48 h, he became afebrile and CSF and blood cultures were negative; he was then discharged. After 96 h of incubation, CSF and blood cultures yielded a gram-negative organism, P. immobilis. The child was readmitted to the hospital, and the same organism was again isolated from his blood and CSF.

Humans↗
PubMed1991

Inhibition of protein-kinase C in peripheral blood mononuclear cells of patients with systemic lupus erythematosus: effect on spontaneous immunoglobulin production.

Systemic Lupus Erythematosus (SLE) is a multisystem disease characterized by an increase in the spontaneous secretion of immunoglobulin (Ig) molecules, many of which are autoreactive. We have previously shown (Biochem & Biophys. Res. Comm. (1989) 161: 1319-1326) that normal human peripheral blood mononuclear cells (PBMCs) can be stimulated to secrete large quantities of Ig upon incubation with the protein kinase-C activator 1 oleoyl-2-acetyglycerol (OAG). Specific blockage of protein kinase C with the isoquinoline sulfonyl piperazine compound (H-7) inhibited the OAG-induced Ig production. In experiments reported here, PBMC of 5 patients with active SLE produced high levels of IgG spontaneously in culture. PBMC of 6 inactive SLE patients and 7 normal control subjects produced comparable low levels of IgG spontaneously. Pokeweed mitogen (PWM) stimulation of PBMC in inactive SLE and control groups, but not active SLE patients produced markedly enhanced IgG production. The lack of response to PWM stimulation in active SLE patients is likely due to inherent maximal stimulation of active SLE B-cells. In addition, we examined the ability of H-7 to inhibit both mitogen-stimulated (normal and inactive SLE) and spontaneous (active SLE) Ig production. In other experiments, we also examined the ability of the isoquinoline sulfonamide (HA-1004), a potent inhibitor of cAMP-dependent protein kinase to regulate mitogen stimulated and spontaneous Ig production in the patient groups indicated above. H-7 significantly inhibited PWM stimulated Ig production in normal (P less than 0.0001) and inactive SLE patients, (P less than 0.040) suppressing PWM stimulated levels to spontaneous levels.(ABSTRACT TRUNCATED AT 250 WORDS)

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1990

Disposition, pharmacokinetics, and metabolism of 14C-fotemustine in cancer patients.

The pharmacokinetics and metabolism of intravenously infused 14C-fotemustine (about 100 mg/m2) were examined in 2 cancer patients. Plasma levels of radioactivity increased to a maximum of 4.1 and 5.5 micrograms equivalents per g when the infusion stopped then declined triexponentially with mean half-lives of about 1/2, 10 and 80 h for the initial, mid and terminal phases, respectively. Plasma levels of intact drug were lower, with maximum levels of 1.1 and 2.8 micrograms/ml, and declined monophasically with a half-life of about 24 min. Plasma clearance was high (1426 and 764 ml/min) with the volume of distribution based on areas of 47.7 and 26.4 l. Most of the radioactivity was eliminated in urine (50.1 and 61.3%) over 7 days with smaller amounts in the feces (6.8 and 0.3%) and only minimal quantities (under 0.1%) as expired carbon dioxide. Metabolites of fotemustine were identified as chloroethanol and N-nitroso-1-imidazolone-ethyl-diethylphosphonate in plasma and as 1-hydantoin-ethyl-diethyl-phosphonate and acetic acid in urine.

Aged↗
PubMed1990

Roots of increased health care inequality in New York.

During the 1970s, New York city experienced an epidemic of housing destruction by contagious fire and building abandonment. This epidemic was triggered by reductions in municipal services, especially fire control, in the poor areas of high population density and aging housing. The rapid loss of low rent housing led to a wave of forced internal migration of the poor within the city and overcrowding of areas adjacent to the burned out ones. The spread of overcrowding spread the high fire incidence. The massive upheaval resulted in destruction of social networks and in degraded living conditions. Public health, as measured by many indices such as disease incidence, substance abuse incidence, infant mortality, and incidence of homicide, deteriorated. This deterioration caused increased demand for hospital health care, especially emergency service. The data on average stay length in the poorest areas in comparison with wealthier areas hints that the overloading of the voluntary hospitals in the poorest areas has caused care rationing and greater inequality in access to care.

Crowding↗
PubMed1990

Fluorescein transport in isolated proximal tubules in vitro: epifluorometric analysis.

An epifluorometric method was used to quantify the bidirectional fluxes of fluorescein across the basolateral surfaces of nonperfused rabbit tubule segments in vitro. Proximal S2 segments, but not cortical collecting tubules or cortical thick ascending limbs, accumulated fluorescein to levels in cytoplasm over 100-fold greater than in the external medium. The rate of intracellular fluorescein accumulation was dependent on the concentration of the ligand in the external bath. The apparent Km was 10 microM and the Vmax was 623 x 10(-6) mol.min-1.l-1. Probenecid and ouabain inhibited fluorescein accumulation. We conclude that fluorescein is transported into the cytoplasm of proximal tubules by basolateral mechanisms that share features in common with the classical organic anion system. This fluorescent compound offers some unique advantages for the study of the organic anion transport system in intact cells.

Animals↗