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Biomedical subjects

M K Mitchell

Publications and source records attributed to M K Mitchell.

16 recordsLinked to original sources
PubMed2006

Leptin antagonist reveals that the normalization of caloric intake and the thermic effect of food after high-fat feeding are leptin dependent.

High-fat (HF) feeding induces a transient increase in caloric intake and enhances energy expenditure. We hypothesized that leptin is necessary for homeostatic restoration of the HF-enhanced caloric intake and may mediate the increase in uncoupling protein-1 (UCP1) in brown adipose tissue (BAT). We employed a leptin antagonist to examine the role of leptin in these biological processes. Simultaneous central administration of leptin and increasing doses of the leptin antagonist revealed a dose-dependent inhibition of leptin-induced hypothalamic signal transducer and activator of transcription-3 phosphorylation, and 7 days of infusion of the leptin antagonist produced the predicted increase in food intake and weight gain. When delivered with exogenous leptin in a 7-day infusion, the leptin antagonist blocked leptin-mediated anorexic effects as well as the increase in BAT UCP1 protein and signal transducer and activator of transcription-3 phosphorylation. Rats were then fed an HF diet (60% kcal as fat) or chow and simultaneously infused with antagonist (25 microg/day into the lateral ventricle) for 7 days and compared with vehicle-infused chow-fed rats. Daily caloric intake of both HF groups peaked on day 2. HF feeding elevated caloric intake, which nearly normalized by day 7, whereas in the presence of the antagonist, caloric intake remained elevated. Moreover, the HF-mediated augmentation in UCP1 in BAT was prevented by the antagonist. These results demonstrate that leptin is essential for the homeostatic restoration of caloric intake after HF feeding and that this leptin antagonist is able to block central leptin signaling and leptin-mediated UCP1 elevation.

Adipose Tissue, Brown↗
PubMed2001

Highly effective adsorption of heavy metal ions by a thiol-functionalized magnesium phyllosilicate clay.

A thiol-functionalized layered magnesium phyllosilicate material (called Mg-MTMS), prepared by a direct and cost-effective co-condensation synthesis, has been investigated as a high-capacity adsorbent for heavy metal ions. Structural characterization by powder X-ray diffraction, infrared spectroscopy, solid-state 13C and 29Si NMR spectroscopies, and elemental analyses confirms the smectite-type structure and the high organic moiety content of this material. Mg-MTMS was found to be highly effective for the adsorption of Hg(II), Pb(II), and Cd(II) ions, exhibiting unprecedented metal ion uptake capacities of 603, 365, and 210 mg of metal/g of adsorbent, respectively. Mg-MTMS shows an equivalent affinity for the three metal ions, removing them from mixed metal solutions with an equal ion uptake capacity (approximately 400 mg of metal/g of adsorbent). Metal-loaded Mg-MTMS can be regenerated by acid treatment without altering the adsorbent properties. The high effectiveness of Mg-MTMS for the capture of metal ions is attributed to both the high concentration of complexing thiol groups (6.4 mmol of SH/g of Mg-MTMS) and the expansion capability of the framework, which facilitates the accessibility of the binding sites.

Adsorption↗
PubMed2000

Prehospital triage in the injured pediatric patient.

BACKGROUND/PURPOSE: Identifying major trauma patients in the prehospital setting is essential in determining management, destination, and best utilization of emergency department resources. Few methods of trauma triage have been accepted unanimously. This study prospectively evaluates the efficacy of comprehensive field triage using 12 criteria (simplified version of the American College of Surgeon's guidelines) in 1,285 pediatric trauma patients. METHODS: Major trauma was defined as occurring in those who died in the emergency room, had major surgery (penetrating injury involving surgery of the head, neck, chest, abdomen, or groin), or were admitted directly to the intensive care unit. The correlation between trauma triage criteria, hospital disposition, and triage accuracy were determined prospectively and compared in the pediatric patients (36 months) with an adult cohort of patients (12 months). RESULTS: A total of 1,285 pediatric trauma patients were evaluated and compared with 1,326 adult trauma patients. The most accurate trauma triage criterion for major injury was a blood pressure < or = 90 mmHg (systolic) with an accuracy of 86%. This was followed by burn greater than 15% total body surface area (79%), Glasgow Coma Scale score < or = 12 (78%), respiratory rate less than 10/min or greater than 29/min (73%), and paralysis (50%). Less accurate criteria included a fall from greater than 20 feet (33%); penetrating injury to head, neck, chest, abdomen, or groin (29%); ejection from vehicle (24%); pedestrian struck at greater than 20 mph (16%); paramedic judgement (12%); rollover (3%); and extrication (0%). The Glasgow Coma Scale score was a more accurate indicator of major injury in children than adults, and paramedic judgement was less accurate in children when compared with adults. Of the 379 major pediatric trauma victims, the Revised Trauma Score and Pediatric Trauma Score missed 36% and 45% of these major trauma victims, respectively. The overtriage rate for children was 71% with a sensitivity of 100% (no missed major trauma patients). CONCLUSIONS: Physiological variables, anatomic site, and mechanism of injury provide a sensitive and safe system of triage. Continued education of prehospital personnel regarding pediatric trauma and stratification of the current triage tools are necessary to minimize overtriage in an era of shrinking resources.

Adolescent↗
PubMed1999

Developmental expression of N-acetyltransferases in C57BI/6 mice.

N-Acetyltransferases (NATs) play an important role in the biotransformation of a wide variety of arylamine drugs and carcinogens. Two genes (NAT1, NAT2) have been identified and allelic variation in NAT2 has been associated with arylamine toxicity in adults. Little information has been reported on expression of NAT genes during embryonic and fetal development although substrate specific NAT activity has been detected. The current study investigated the expression of NAT1 and NAT2 in mice pre-and postnatally. RNA was isolated from maternal liver, embryonic tissue at gestational days (GD) 10, 15, and 18, or neonates at neonatal day 3. Reverse transcription-polymerase chain reaction was performed using primers designed to amplify portions of either the NAT1 or the NAT2 gene. NAT1 and NAT2 mRNAs were detected in the embryo/placental complex at GD 10 and in GD 15 and 18 embryos. NAT2 but not NAT1 was expressed in GD 18 and neonatal day 3 hepatic tissue. These data demonstrate the differential expression of NAT genes in the mouse embryo and suggest a potential role for NAT in development.

Acetyltransferases↗
PubMed1997

Domestic violence: teaming communities with providers for effective intervention.

For battered women, it is essential that health care providers begin to address the causes of domestic violence injuries--not just the result. Community involvement is necessary for the interventions to be effective, and the health care system is uniquely positioned to intervene as the universal point of entry for abused women. The article outlines some of the challenges in addressing domestic violence, identifies barriers to addressing the problem, and offers suggestions for overcoming the barriers in the current health care environment.

Community Health Nursing↗
PubMed1992

CHAP: nursing's legacy of leadership.

In the story of CHAP's fight for deemed status, Mitchell, CHAP's president, finds important opportunities for nursing to exert moral leadership and initiate political reforms that will have a lasting impact on the quality of community-based care.

Accreditation↗
PubMed1989

In vitro solubility of calcium glycerophosphate versus conventional mineral salts in pediatric parenteral nutrition solutions.

Low-birth-weight infants requiring total parenteral nutrition receive inadequate intakes of calcium (Ca) and phosphorus (P) due to poor solubility of available mineral salts. To optimize Ca/P delivery, we tested the effects on in vitro solubility of mineral salt:calcium glycerophosphate (CaGP) versus calcium gluconate and K2HPO4 (CG + P); Ca:P ratios of 1:1 (at 12.5 and 25 mmol/L of Ca and P) and 2:1 (25:12.5 mmol/L); amino acid (AA) formulation: Aminosyn (A), Aminosyn-PF (A-PF), TrophAmine (T) or Vaminolac (V); and AA concentration (25 versus 8.3 g/L). Parenteral nutrition solutions contained 10% dextrose and vitamins and minerals typical of a neonatal prescription. Solutions were sampled at preparation, after 24 h in the neonatal unit (25 degrees C), and from before and after a 0.22-micron filter in extension tubing through which solutions were pumped at 5 ml/h within an incubator at 37 degrees C. Samples were analyzed for Ca and pH, and precipitation by spectrophotometry at 600 nm and light microscopy at x 100 magnification. The Ca concentration was unaffected by filtration. While spectrophotometry detected only gross precipitation, with light microscopy crystal formation was evident with 25 mmol/L of Ca and P as CG + P in A and T at 25 g of AA/L and in A, V, T, and A-PF at 8.3 g of AA/L. Precipitation did not occur with CaGP or CG + P at 12.5 mmol/L of Ca and P. Under in vitro conditions mimicking the neonatal unit, CaGP versus CG + P resulted in greater mineral solubility even at low AA concentrations.

Amino Acids↗
PubMed1989

Long-term care.

Explore the source record for details and available documents.

Continuity of Patient Care↗
PubMed1988

The Community Health Accreditation Program. Its strategic meaning to the home care industry.

For many reasons, the Community Health Accreditation Program represents the home care industry's best strategic choice as a mechanism to assure and promote the quality as well as the growth of the health care industry. First and foremost, CHAP is a program with a rich tradition and commitment to community health and home care. With a quarter of a century of experience, CHAP knows well that the philosophy o providing care in the home, the methods, and the practitioners who provide care in the home are of a different nature from those who provide in-patient care. If we fail in our growth phase to protect and maintain the uniqueness of home care, we will have lost our greatest asset. Fundamentally CHAP, as a voluntary accreditation process, is built on a firm foundation of commitment to quality by the industry itself and includes a genuine desire to integrate quality improvement into each and every aspect and business function of the services provided. As a voluntary accrediting body. CHAP seeks to become a partner that provides the information and supports the home care industry's quest for quality. CHAP's aim is to provide what the home care industry needs most--experts in key aspects of management--to assist agencies in achieving superior performance. Quality must begin at the top, and it must be inspired and developed within the industry itself. Staff regulatory approaches will not achieve quality; in fact recent studies indicate that regulation may have quite the opposite effect. There is evidence to suggest that patient care is worse in highly regulated states.(ABSTRACT TRUNCATED AT 250 WORDS)

Accreditation↗
PubMed1986

Cyclic amines are selective cytotoxic agents for pigmented cells.

We have shown that morpholine, a cyclic amine, exerts a selective inhibition of growth on melanocytic pigmented cell lines compared to nonpigmented cells. The ID50 of morpholine for the pigmented B-16 cell line HFH was 1200 micrograms/ml, compared to values greater than 2400 micrograms/ml for baby hamster kidney, Chinese hamster ovary and NP, an unpigmented primate cell line. Two other cyclic amines piperazine and piperidine, were similarly found to be selectively toxic to melanocytes. This selective toxicity could be synergistically enhanced by pretreatment of the cells with theophylline, a stimulator of tyrosinase activity, which indicates that the selective toxicity may be associated with melanin synthesis. Low passage HFH, high passage HFH and Syrian hamster melanoma RPMI 1846 cells that were pretreated with theophylline showed between 13 and 29% greater toxicity compared to controls treated with theophylline or morpholine alone. Unpigmented NP primate cells, Chinese hamster ovary and mouse fibroblast L929 remained unaffected. These cyclic amines join a list of other amines that have also been shown to be melanocytotoxic.

Animals↗
PubMed1986

Serine hydroxymethyltransferase from soybean root nodules : purification and kinetic properties.

Serine hydroxymethyltransferase has been purified 1,550-fold from the plant fraction of soybean (Glycine max [L]. Merr. cv Williams) nodules. The pH optimum for the enzyme was at 8.5. The native molecular weight was 230,000 with a subunit molecular weight of 55,000 which suggested a tetramer of identical subunits. The enzyme kinetics for the enzyme were Michaelis-Menten; there was no evidence for cooperativity in the binding of either substrates or product inhibitors. There were two K(m) values for serine at 1.5 and 40 millimolar. The K(m) for l-tetrahydrofolate was 0.25 millimolar. l-Methyl-, l-methenyl-, and l-methylene-tetrahydrofolates were all noncompetitive inhibitors with l-tetrahydrofolate with K(i) values of 1.8, 3.0, and 2.9 millimolar, respectively. Glycine was a competitive inhibitor with serine with a K(i) value of 3.0 millimolar. The intersecting nature of the double reciprocal plots together with the product inhibition data suggested an ordered mechanism with serine the first substrate to bind and glycine the last product released. The enzyme was insensitive to a wide range of metabolites which have previously been reported to affect its activity. These results are discussed with respect to the roles of serine hydroxymethyltransferase and the one-carbon metabolite pool in control of the carbon flow to the purine biosynthetic pathway in ureide biogenesis.

Journal Article↗