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Biomedical subjects

M Hart

Publications and source records attributed to M Hart.

At least 37 records · Page 2Linked to original sources
PubMed1998

Expansion and division of conjoined twins.

Omphalopagus conjoined twins were born by cesarean section after their 24-year-old gravida 2, para 1 mother went into labor at 35 weeks' gestation. Initial studies included roentenograms, an upper gastrointestinal study, small bowel follow-through, and computerized tomography with intravenous contrast from neck through pelvis. Results of these studies showed that the twins had very little shared vasculature, but did share a pericardium and liver parenchyma. The infants were allowed to gain weight and grow. After 3 weeks, tissue expanders were placed subcutaneously and were rapidly expanded in 2 weeks. The infants were then separated. An Argon Beam Coagulator was used to aid the separation of the liver. The abdominal fascia was closed primarily on each infant, and the skin easily closed without tension. During the first 36 hours of the postoperative course, both infants required significant ventilatory support including inhaled nitric oxide. After this period, the ventilatory support decreased dramatically and rapidly. The infants were discharged 9 days after their surgical separation. Conjoined omphalopagus twins, the use of tissue expanders and the Argon Beam Coagulator, and the postoperative course are discussed.

Contrast Media↗
PubMed1998

Total enteral nutrition versus total parenteral nutrition during pediatric extracorporeal membrane oxygenation.

OBJECTIVE: To evaluate the adequacy, tolerance, and complications of enteral nutrition, compared with parenteral nutrition, in pediatric patients requiring extracorporeal membrane oxygenation (ECMO). DESIGN: A retrospective chart review of all patients placed on extracorporeal life support from January 1991 through December 1995. SETTING: Medical/surgical pediatric intensive care unit at Egleston Children's Hospital, a tertiary care pediatric center. PATIENTS: Twenty-nine consecutive pediatric patients who required ECMO and were provided nutritional support, either enterally or parenterally. Group A consisted of 14 patients who were provided nutritional support using total parenteral nutrition. Group B consisted of 15 patients. Two patients were excluded from group B because their ECMO run was <36 hrs, leaving insufficient data for analysis. The remaining 13 patients were provided total enteral nutrition during ECMO. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Both groups were similar in age, weight, pre-ECMO oxygenation index, alveolar-arterial oxygen difference, type, and duration of ECMO (p = NS). Comparison of percent ideal body weight on admission did not show a statistical difference between groups A and B (p = .883). There was no difference between the two groups in the time needed to achieve caloric goal (p = .536) from the initiation of ECMO. No complications were associated with the utilization of enteral feedings. Savings for the nutritional supplement was estimated to be $170 per day for the enterally fed group. The percentage of patients surviving was higher in the enterally fed patients compared with the parenterally fed group (79% vs. 100%), although this difference was not statistically significant (p = .47). CONCLUSIONS: Enteral nutrition in patients receiving either venoarterial or venovenous ECMO is well tolerated, provides adequate nutrition, is cost effective, and is without complications, as compared with parenteral nutrition. These data suggest that total enteral nutrition can be safely administered for nutritional support in pediatric patients undergoing either venoarterial or venovenous ECMO.

Adolescent↗
PubMed1998

Plasma thyroid hormones in premature infants: effect of gestational age and antenatal thyrotropin-releasing hormone treatment. TRH Collaborative Trial Participants.

Thyroid hormones are important for both perinatal adaptation and long-term psychomotor development; however, there is limited information on the effects of extreme prematurity and antenatal TSH-releasing hormone (TRH) treatment on pituitary-thyroid function. In this study we assayed plasma triiodothyronine (T3) and TSH in infants who were part of a collaborative trial of antenatal maternal TRH therapy. Within the control population (n = 166), infants of 24-28-wk and 28-32-wk gestational age had comparable levels of T3 (0.94 and 1.06 nmol/L, respectively) and TSH (5.7 and 7.2 mU/L) at birth, but the increases at 2 h and subsequent T3 levels were less in the 24-28 wk versus 28-32-wk gestation infants. In the TRH-treated group (n = 131), T3 was lower in the first day for infants delivered 7-72 h after antenatal TRH compared with control infants. TSH at birth was approximately 3.5-fold greater for infants delivered at 0-6 h after the last TRH dose compared with the control group and was suppressed in infants delivering at 7-36 h. T3 and TSH levels were not different between control and TRH-treated groups at 3-28 d of age. In TRH stimulation tests on d 28, control and TRH-treated groups had similar peak levels of TSH and incidence of exaggerated response (TSH > or = 35 mU/L). We conclude that extremely premature infants have a reduced postnatal surge in TSH and T3 and maintain lower T3 concentrations, probably reflecting tertiary hypothyroidism. The stimulatory and suppressive effects of antenatal TRH treatment observed at birth are transient and do not affect pituitary-thyroid responsiveness at 28 d of age.

Congenital Hypothyroidism↗
PubMed1997

The nomadic engram: overtraining eliminates the impairment of discriminative avoidance behavior produced by limbic thalamic lesions.

Combined lesions of the medial dorsal and anterior thalamic nuclei severely impair the acquisition of discriminative avoidance behavior, wherein rabbits learn to prevent foot-shock by stepping after a tone conditional stimulus (CS+), and they learn to ignore a different tone (CS-) that does not signal foot-shock. Neurons in these thalamic nuclei exhibit training-induced firing pattern changes during behavioral acquisition to asymptotic performance levels. However, the changes decline in magnitude during the course of post-asymptotic training (overtraining), suggesting a declining participation of the thalamic neurons in task mediation. In order to test this hypothesis, electrolytic or sham limbic thalamic lesions were induced either immediately after asymptotic performance was reached, or after the administration of training to asymptote and ten additional overtraining sessions. Retention after the lesions was assessed using an extinction procedure (CS presentation without foot-shock) followed by re-acquisition. Rabbits given lesions after criterion attainment exhibited a significant retention deficit during both the extinction and re-acquisition tests. However, no significant retention deficit was found in rabbits given 10 days of overtraining prior to the lesions. These results support the prediction derived from the neuronal data, of a time-limited involvement of limbic thalamic neurons in mediation of discriminative avoidance behavior.

Animals↗
PubMed1997

Monitoring quality in the British health service--a case study and a theoretical critique.

Details the results of a monitoring exercise introduced in one local hospital to address the amount of time that patients spent waiting when attending outpatient departments in hospitals. Discusses whether a purely quantitative approach to quality can deliver the desired improvements. Argues that quality measures should incorporate more qualitative dimensions, including the tapping of patient perceptions of their experiences, before a claim can be made that reducing waiting times has improved overall quality. Also argues that the frequent use of the term customer in the quality literature receives critical attention when it is applied in the NHS. The fact that the term conflates the roles of consumer and purchaser makes analysis potentially difficult. Suggests that regarding patients as customers (in the manner of some traditional approaches to quality) is not a useful aid to analysis.

Humans↗
PubMed1996

Activation of phospholipase D and phosphatidylinositol 4-phosphate 5-kinase in HL60 membranes is mediated by endogenous Arf but not Rho.

Membrane-associated phospholipase D (PLD) in HL60 cells can be activated by the small GTP-binding proteins Arf and RhoA, but polyphosphorylated inositol lipids were required for maximum activity. The intact lipid was required because neither inositol 1,4, 5-trisphosphate nor stearoyl-arachidonyl glycerol could substitute for phosphatidylinositol 4,5-bisphosphate (PIP2). Arf-stimulated but not Rho-stimulated PLD activity was increased by the inclusion of Mg2+ and ATP. ATP-dependent PLD activation occurred when phosphatidylinositol 4-phosphate (PIP), PIP2, or phosphatidylinositol 3,4,5-trisphosphate (PIP3) were included, but PIP2 formation was only detected with PIP; no PIP3 production was detected under any conditions. Therefore, the ATP-dependent increase in PLD activity cannot be explained by PIP2 or PIP3 formation. Association of endogenous Arf and RhoA with membranes was increased by incubation with GTPgammaS. This treatment increased membrane PLD and PIP kinase activities in the absence of exogenous p21 proteins. Reduction of Arf translocation suppressed the increase in PLD and PIP kinase activities, whereas complete removal of Rho but not Arf from membranes with RhoGDI was without effect on PLD activity but increased PIP kinase activity. Therefore, although recombinant Arf and Rho can activate PLD and PIP kinase in HL60 cells, it is the endogenous Arf but not Rho that regulates PLD, and thus a role for Rho in the physiological regulation of PLD in HL60 cells is unlikely.

ADP-Ribosylation Factors↗
PubMed1996

Release of leukemia inhibitory factor in primate sepsis. Analysis of the role of TNF-alpha.

Leukemia inhibitory factor (LIF), a pleiotropic cytokine with many biologic effects overlapping with those of IL-6, has been implicated in the pathogenesis of sepsis. We here analyzed the kinetics of LIF in 13 baboons challenged with a lethal (n=6) or sublethal (n=7) dose of Escherichia coli. In addition, to assess the role of TNF-alpha in the induction of LIF in vivo, seven baboons were studied that had either received a bolus injection of recombinant human TNF-alpha (100 micrograms/kg, n=3), or to whom 15 mg/kg of an anti-TNF mAB before lethal E. coli challenge was administered (n=4). LIF levels increased 2 h after E coli challenge, and reached maximum values at 4 and 8 h after a sublethal (4.4 +/- 1.6 ng/ml) or lethal (40.9 +/- 3.8 ng/ml) dose, respectively. TNF-alpha injection induced a modest rise in LIF concentrations, peaking after 6 h (228 +/- 46 pg/ml). Circulating LIF correlated with plasma levels of IL-6, both after E. coli challenge (Spearman Rank coefficient of correlation (r) = 0.849, p<0.001), as well as upon TNF-alpha injection (r=0.863, p<0.001). Moreover, the E. coli-induced release of either cytokine was reduced 6- to 10-fold after pretreatment with anti-TNF mAb, except in one nonsurviving animal, which exhibited a progressive increase of LIF and IL-6 levels despite the absence of TNF immunoreactivity. These results show that TNF-alpha is an intermediate factor in concerted release of LIF and IL-6 in vivo, and indicate that the enhanced elaboration of these cytokines may predict disease outcome in severe sepsis.

Animals↗
PubMed1996

Improving the quality of NHS out-patient clinics: the applications and misapplications of TQM.

Presents and discusses the results of a monitoring programme instituted to comply with the objectives laid down in The Patient's Charter. Explores the dangers inherent in attempting to assess the quality of out-patient clinics by the use of single, simplistic indicators such as a waiting time. Examines the ways in which total quality management has been deployed in a health-service context and pays particular attention to the way in which the concept of ¿the customer¿ may need considerable refinement. Suggests incorporating more user-centered approaches into evaluations of quality in the National Health Service, such as the patient satisfaction survey and the application of the SERVQUAL model of consumer satisfaction. Refines the concept of ¿ecological validity¿ in an attempt to capture the perceptions and world views of all of the participants in episodes of out-patient care in order to derive more complete measures of quality.

Appointments and Schedules↗
PubMed1996

Improving the quality of out-patient services in NHS hospitals: some policy considerations.

One of the key objectives in the Patient's Charter was to reduce the amount of time typically spent waiting for treatment in NHS out-patient clinics, a documented source of discontent. Presents the results of a quality improvement programme instituted at Leicester General Hospital. Discusses some of the techniques and problems encountered in the measurement exercise. While the results of the monitoring exercise indicated that waiting times were being radically reduced, doubt is expressed as to whether this one simplistic indicator is sufficient to measure the overall quality of out-patient clinics. There is a danger that measurement systems have concentrated on that which is measurable rather than that which is significant. In particular, the voice of the patient is not incorporated into the league table approach to out-patient quality. Discusses several approaches to the measurement of overall quality and the problems and dangers inherent in adopting a league table approach to quality measurement.

Appointments and Schedules↗
PubMed1996

Incorporating outpatient perceptions into definitions of quality.

This paper reviews the ways in which quality measures have been defined by reference to objective measures and applied by the producers of health care to patients. Patient satisfaction surveys may be thought to redress this imbalance and will be addressed as a precursor to the discussion of the SERVQUAL methodology, developed to measure the gap between expectations and performance in service industries. An argument will be advanced that quality measurement is still producer-led and should incorporate the views of patients more directly into the quality measurement process. It is suggested that calibration or baseline surveys of patients be conducted which then identify the issues that may be subject to more sustained quantitative analysis. Quality monitoring should be conducted in such a way that particular sub-groups can be subject to routine analysis. Models of quality measurement need to incorporate the perspectives of many 'key players' in which the views of patients are complemented by relevant professional, clinical and managerial groups. The extent to which there is a disjunction between quality as objectively measured (e.g. by waiting times) and as experienced by patients will receive attention. Suggestions will be made that monitoring and clinic operations need to be more mutually reinforcing.

Appointments and Schedules↗