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Biomedical subjects

J Moon

Publications and source records attributed to J Moon.

At least 73 records · Page 4Linked to original sources
PubMed1988

Correlation clusters in the accumulation of metals in human scalp hair: effects of age, community of residence, and abundances of metals in air and water supplies.

Scalp hair samples taken from 122 children and 27 adults from three native Indian villages in northern Alberta, Canada were analyzed for 32 metals, in an attempt to trace industrial pollution into the human population. One of the villages has been exposed since 1967 to increased levels of several metals due to its proximity to the world's first two oil sands petroleum extraction plants (Suncor and Syncrude), which release large amounts of metals into the environment. Metal-enriched particulates are emitted at a rate of 547-780 kg h-1 for Suncor, and 713-1067 kg h-1 for Syncrude. To test the hypothesis that hair content reflected accumulation of environmental metals, water and aerometric samples were collected and analyzed for their metal content. These analyses demonstrated that elevated levels of nine metals in hair from children in one of the control villages (Garden River) are (with the exception of Al) correlated with increased levels of metals in water and air. Moreover, increased levels of Cu, but lowest levels of all other metals were found in hair and environmental samples from one control village (Fort Chipewyan). Correlation matrices for metals in the hair samples revealed three sets of highly intercorrelated metals ('correlation clusters'): (i) Pb/Cd; (ii) Al/V/Fe; (iii) Ca/Mg/Sr/Ba. These groups of metals were significantly intercorrelated (r greater than 0.6, p less than 0.001) in the total population, and in both children and adults, or both males and females, as well as when the population was compared according to community of residence. The robustness of the clusters is particularly noteworthy in view of large differences in the proportions and absolute amounts of the various metals in hair from children in the three villages. Plots of metal levels in hair as a function of age of subject reveal a dramatic decrease in concentrations of Al, V, and Fe during the first years of life. The high levels of Al and V in hair from very young children may reveal a lower selectivity in metal absorption, and a higher risk of toxicity during a period of rapid growth when need for nutritionally essential metals is particularly high.

Adult↗
PubMed1988

Active oxygen in neuromuscular disorders.

Although muscle and nerve are reasonably well protected against active oxygen and related free radicals, environmental or inherited malfunctions can overpower their defences. Active oxygen is involved in many neuropathies and myopathies. In every case the damage is caused by agents which exert effects disproportionately greater than the quantities encountered, through a variety of amplification mechanisms. We can categorize these amplification mechanisms as follows: (a) non-replacement of targets (e.g. loss of genetic information, ataxia telangectasia being an hereditary ataxia in which an oxygen mediated chromosomal instability is apparent), (b) non-removal of unwanted materials (e.g. lipofuscin accumulation in brain and heart), (c) redox cycling, usually involving catalysis by trace-metal ions (e.g. some forms of Parkinsonism), (d) non-redox catalysis (e.g. toxicity in cardiac muscle or brain due to vanadium or aluminium respectively), (e) modification of ion transport (e.g. calcium ionophore or acrylamide induce histopathological changes in muscle, similar in some respects to those seen in Duchenne muscular dystrophy), (f) compromised defences (e.g. muscle and nerve become particularly susceptible to free radical damage after loss of the protective actions of vitamin E), and (g) amplification by inflammatory and immune responses (e.g. multiple sclerosis, reperfusion injury to brain and heart, and traumatic injury to nervous tissue). Unfortunately, a variety of therapeutic agents which might be expected to protect against almost every conceivable form of oxygen mediated damage have proved clinically ineffective in most of these disorders. The reasons for this will be explored with an emphasis on common features, differences, mechanisms, and potential therapeutic approaches.

Humans↗
PubMed1986

Trace metals in scalp hair of children and adults in three Alberta Indian villages.

This study examined trace metal levels in scalp hair taken from 122 children and 27 adult residents of three small northern Alberta (Canada) Indian villages, one of which is situated close to the world's first tar sands oil extraction plants. The three communities studied were: Fort McKay (the exposed village), Fort Chipewyan (also in the tar sands ecosystem but distant from the plants), and Garden River (not in the tar sands ecosystem). Inductively coupled argon plasma emission spectroscopy was used to determine hair sample metal content. Nineteen metals were included in data analysis. Children from Fort McKay had the highest average hair lead, cadmium and nickel levels. Chromium levels were approximately equal in hair from Fort McKay and Garden River children, and significantly elevated above levels found in the hair of Fort Chipewyan children. Children from Garden River showed highest hair levels of eight metals: vanadium, aluminum, iron, manganese, barium, zinc, magnesium and calcium. Fort Chipewyan children had the highest hair levels of copper, but the lowest levels of all other metals. Among adults, hair lead, nickel and cadmium levels were highest in Fort McKay residents, while phosphorous and vanadium were highest in hair from Garden River residents. Bioaccumulation of lead, cadmium, nickel and chromium in hair from Fort McKay residents may be related to exposure to extraction plant pollution. Plant stack emissions are known to contain appreciable amounts of lead, nickel and chromium. Spills into the Athabasca River, until recently the source of Fort McKay drinking water, have been reported from plant wastewater holding ponds, known to contain elevated levels of lead, nickel and cadmium. An increased number of significant metal-metal correlations in hair metal levels for Fort McKay children suggests a richer source of multiple metal exposure, relative to children in the other two communities.

Adolescent↗
PubMed1986

A crossed polaroid-pinhole device.

The study describes the use of a pinhole device in which the light-absorbing area surrounding the holes is varied by polarizing filters. The study demonstrates that a pinhole aperture of 1.6-1.8 mm in diameter with polaroids crossed at 90 degrees will allow a visual acuity equal to or better than 20/40 in the face of refractive errors of 1, 2, and 3 diopters. The study next evaluates the effects of pinholes of different sizes and the polarizing components crossed at angles less than 90 degrees. The study concludes by showing that polaroids crossed at between 75 degrees and 85 degrees allow a greater depth of focus, a larger visual field, and greater illumination than traditional pinhole devices.

Humans↗
PubMed1985

Bromocriptine and the hypothalamic hypophyseal function in patients with chronic renal failure on chronic hemodialysis.

Ten patients with chronic renal failure on chronic hemodialysis had the following tests to evaluate the integrity of the hypothalamic hypophyseal axis: (A) glucose tolerance test, (B) thyrotropin releasing hormone stimulation test, (C) clonidine stimulation test, (D) insulin induced hypoglycemia, and (E) LH/RH stimulation test. The majority of those tests were abnormal and prolactin values were found to be moderately elevated in all the patients. Bromocriptine (1.25 mg twice a day) was given to all the patients for 1 month and then, while on bromocriptine, the tests were repeated. Although there is a decrement in the concentration of serum prolactin level, none of the hypothalamic hypophyseal abnormalities were corrected. However, five of the ten patients reported an improvement of their impotence with bromocriptine. The patients who responded had high levels of FSH and LH with levels of testosterone above 1 mg/mL. The nonresponders had low FSH and LH levels and very low testosterone levels. Therefore, bromocriptine, although possibly beneficial in some dialysis patients, is not a drug that can normalize abnormal functioning of hormones in the dialysis population.

Adult↗
PubMed1984

Aerodynamic properties of four tracheoesophageal puncture prostheses.

Airway resistance calculations were completed for two tracheoesophageal puncture prostheses (American V. Mueller Blom-Singer Voice Prosthesis and BIVONA Low Resistance Voice Prosthesis), which have recently become available on a commercial basis. These calculations were compared with those made previously for two, existing prostheses: the Blom-Singer duckbill and the Panje Voice Button. Substantial differences in airway resistance properties exist among these four devices. BIVONA Low Resistance devices exhibited the lowest resistance (less than 50 cm H2O/liters per second [LPS]); Panje Voice Buttons exhibited the highest (180 to 200 cm H2O/LPS); and Blom-Singer devices exhibited intermediate values (110 to 125 cm H2O/LPS) of opposition.

Air↗
PubMed1981

A system for slit-lamp polaroid photography.

A system is described in which a SX-70, Alpha Model II, Polaroid, single lens reflex camera, and photoflash unit can be quickly and sturdily mounted to a slit lamp. Such a system can take sharp anterior segment prints of the eye at all slit-lamp magnifications, with white light and in the flourescein mode. The heart of the unit is the modification of an assembly initially designed to attach the camera to a light microscope. The small flash unit and power supply were designed specifically for slit lamp usage. Examples of "instant" photos of the anterior segment at different magnifications are presented.

Contact Lenses↗
PubMedDate not supplied

The Miami experience with almost 100 multivisceral transplants.

We report our experience with 98 patients who received primary multivisceral transplantations. Three eras can be distinguished based on the evolution of technique, immunosuppression, and monitoring: August 1994 to December 1997 (first era); January 1998 to December 2000 (second era); and January 2001 to present (third era). Sixteen patients were transplanted during the first era, 18 during the second era, and 64 during the third era. Fifty-three patients are alive with a median follow-up of 37.5 months (range: 1 to 116 months). The leading cause of mortality was infection (n = 17), followed by rejection (n = 6). Seven patients required retransplantation and five of them subsequently died. The estimated 3-year survival was 25% +/- 11% for era 1; 44% +/- 12% for era 2; and 58% +/- 7% for era 3. Additionally, 45.3% (29/64) of patients in the third era never developed rejection versus 23.5% (8/34) of patients in the first two eras combined. The percentage of patients who developed a moderate or severe rejection was significantly less in the third era compared with the first two eras combined, 31.6% (20/64) versus 67.6% (23/34). A comparison of the hazard rate of developing severe rejection showed a protective effect of the multivisceral graft (P = .0001). In conclusion, multivisceral transplantation is indicated for patients with short bowel syndrome and extended abdominal catastrophies. Evolution in surgical techniques, immunosuppression, and monitoring have improved patient survival, which is now similar to that of other complex solid organ transplants.

Cause of Death↗
PubMedDate not supplied

An association of lower serum citrulline levels within 30 days of acute rejection in patients following small intestine transplantation.

INTRODUCTION: In a prospective protocol we studied whether serum citrulline level within 30 days of an acute rejection was predictive of the episode. METHODS: An acute rejection episode was defined as the date of occurrence of any biopsy-proven rejection in which treatment was initiated until two successive biopsies showed no further rejection. We compared the mean citrulline level based on values determined within 30 days of the start of an acute rejection episode with the mean citrulline level measured on the same patient during a rejection-free period. Serum citrulline measurements were available immediately prior to the occurrence of rejection for 22 patients who experienced 37 episodes. RESULTS: For the 12 episodes of mild rejection, the mean serum citrulline level +/- SE (standard error) was 15.0 + 2.3 micromol/L prior to rejection and 18.8 +/- 2.4 micromol/L during the rejection-free periods. A paired t test of the mean differences was not significant (P = 17). For the 25 episodes of moderate or severe rejection, the mean serum citrulline level was 12.4 +/- 1.1 micromol/L before rejection and 18.8 +/- 2.0 micromol/L during the rejection-free periods. A paired t test of the mean difference was statistically significant (P = .002). CONCLUSIONS: Although further study of citrulline as a marker for the early detection of acute rejection episodes is needed, our hope is that its use will help to prevent some of these early episodes from evolving into full-blown moderate or severe grades of rejection.

Acute Disease↗
PubMedDate not supplied

CD55 and CD59 deficiency in transplant patient populations: possible association with paroxysmal nocturnal hemoglobinuria-like symptoms in Campath-treated patients.

Campath-1H therapy is directed to CD52, a small mw protein that has a glycosylphosphatidylinositol (GPI) anchor, which has a conventional structure similar to other GPI anchors such as CD55 and CD59. Paroxysmal nocturnal hemoglobinuria (PNH) results when cells have a somatic defect in the synthesis of GPI anchors and lack CD55 and CD59, as well as CD52. Several patients treated with Campath developed PNH-like symptoms with hemolysis and thrombosis. These patients were followed after therapy by measurement of peripheral CD55 and CD59 levels and showed an increased number of cells deficient in the expression of these molecules. Thereafter we instituted a screening program for the presence of CD55/59 levels in all pretransplant patients. Our results show that 17.3% of all pretransplant samples contained abnormal (9.7% of samples) or slightly abnormal (7.6% of samples) levels of granulocytes deficient in CD55 or CD59. This high prevalence of CD55/59 deficiency in Campath-treated patients with PNH-like symptoms suggests that a lack of these molecules (including CD52) could predispose to a complication of this immunosuppressive therapy.

Alemtuzumab↗
PubMedDate not supplied

Mucosal fibrosis in intestinal transplant biopsies correlates positively with the development of chronic rejection.

Endoscopic biopsies of intestinal allografts are limited to the superficial layers of the bowel. We investigated whether the presence of mucosal fibrosis in graft biopsies was indicative of chronic allograft rejection. We examined graft biopsies of 182 intestinal transplant recipients for the presence of mucosal fibrosis. Kaplan-Meier analysis showed that within 5 years posttransplantation 33% of intestinal transplant patients had graft biopsies positive for mucosal fibrosis. Although the presence of mucosal fibrosis did not affect patient or graft survival, patients with this lesion were at higher risk of developing chronic allograft enteropathy.

Adult↗