The adequacy of limb escharotomies-fasciotomies after referral to a major burn center

To determine the frequency of inadequate decompression and its complications, the medical records of 108 pediatric burn patients requiring escharotomies or fasciotomies were reviewed. Of 108 patients, 100 (93%) had escharotomies or fasciotomies performed at an outlying facility before transfer. Of these 100 patients, 44 (117 limbs) were inadequately decompressed and required further decompression after admission to our facility. Initial mean compartment pressures were 50.3 +/- 1.3 mm Hg, which were reduced to 16.3 +/- 0.5 mm Hg after decompression. Pulses were present in 74% of limbs requiring decompression. Twenty limbs required decompression despite noncircumferential burns. Complications of inadequate or delayed decompression included foot drop in 20 patients (35 limbs) and muscle necrosis in 13 patients (23 limbs). Four patients (seven limbs) required amputations because of progressive muscle necrosis and infection. Complications of the procedure itself were limited to bleeding in three patients. In conclusion, compartment pressures should be followed in patients with significant burns since pressures may increase over time and pulses are not predictive of ischemia. Failure to decompress extremities with elevated pressures leads to significant but preventable complications.

Crystallization and preliminary X-ray diffraction studies on cytosolic (class 1) aldehyde dehydrogenase from sheep liver

The cytosolic (Class 1) aldehyde dehydrogenase (AlDH) from sheep liver has been crystallized in a form suitable for X-ray diffraction studies. The crystals, grown by vapour diffusion using 6.5 to 7.5% methoxypolyethylene glycol 5000 as precipitant, at pH 6.5, are orthorhombic with cell dimensions a = 80.7, b = 92.5, c = 151.6 A, space-group P2(1)2(1)2(1), and one dimer in the asymmetric unit. The crystals diffract to at least 2.8 A resolution. Although unmodified AlDH crystallized readily, a key factor in obtaining diffraction-quality crystals was the covalent attachment of an active site reporter group, provided by 3,4-dihydro-3-methyl-6-nitro-2H-1,3-benzoxazin-2-one.

PDGF and TGF-alpha act synergistically to improve wound healing in the genetically diabetic mouse

Impaired wound healing results in significant morbidity for the surgical patient. The genetically diabetic (C57BL/KsJ-db/db) mouse is obese, hyperglycemic, insulin-resistant, and exhibits markedly impaired wound healing. Previous studies have demonstrated that the fibroblast mitogens, BB homodimer of platelet-derived growth factor (PDGF-BB) or basic fibroblast growth factor, plus insulin-like growth factor, act synergistically to enhance wound closure in the genetically diabetic mouse. The purpose of this study was to determine whether the keratinocyte mitogens, epidermal growth factor (EGF) or transforming growth factor-alpha (TGF-alpha), in combination with the fibroblast mitogen, PDGF-BB, would produce a similar synergistic enhancement in tissue repair. Full-thickness skin wounds created on the backs of diabetic mice received topical applications of vehicle (5% polyethylene glycol), PDGF-BB (10 micrograms), EGF (1 microgram), TGF-alpha (1 microgram), or the combination of PDGF (10 micrograms) and EGF (1 microgram) or TGF-alpha (1 microgram) for 5 consecutive days starting at wounding. Application of PDGF-BB or TGF-alpha alone to wounds in diabetic animals improved wound closure when compared to vehicle treatment. EGF did not affect healing and did not have any additive effects when combined with PDGF-BB. Significant improvements in wound closure were observed with the combination of PDGF-BB and TGF-alpha when compared to treatment with the individual growth factors. The PDGF-BB/TGF-alpha combination accelerated healing in the diabetic animals to a rate that was closer to that seen in nondiabetic mice.(ABSTRACT TRUNCATED AT 250 WORDS)

Phosphorus magnetic resonance spectra and changes in body composition during weight loss

OBJECTIVE

The use of magnetic resonance spectroscopy (MRS) to monitor cellular bioenergetics during weight loss may provide novel insights regarding metabolic functioning.

METHODS

Changes were noted in 18 sedentary, moderately overweight women following a 7-week program consisting of a low-fat, 422-428 MJ/day (1010-1025 kcal/day) diet, a progressive walking program, a vitamin-mineral-fortified, isolated-protein meal supplement drink and a weekly group meeting. Mitochondrial energy production and utilization were assessed by measuring the concentrations of inorganic phosphate (Pi) and phosphocreatine (PCr) through magnetic resonance spectroscopy. Anthropometric changes were also monitored.

RESULTS

Dietary analysis of subjects' pre-intervention food records showed intakes of numerous vitamins and minerals below 100% of the Recommended Dietary Allowances (RDA), most commonly for folic acid, vitamin E, magnesium, iron and zinc. Relative to pre-intervention levels, final measurements showed that all women lost body weight, ranging from 2.6 to 10.0 kg. Body mass index declined in all subjects, from 0.55 to 3.86 kg/m2. All subjects lost fat mass, ranging from 0.9 to 10.4 kg. Seventeen of 18 women showed a decline in their percentage of body fat, ranging from 2.3 to 10.1%. Twelve of 18 subjects showed an increase of 0.1-3.5 kg of fat-free mass, with half of these values increasing by > 1.0 kg. No changes from baseline levels were found in the Pi/PCr ratio over 7 weeks under resting, exercise or recovery conditions, suggesting a preservation in muscle energy function over the course of the study while the subjects were losing fat mass and total body weight.

CONCLUSIONS

The possible metabolic advantage associated with a program that employs moderate energy restriction, repletion of vitamin and mineral intakes to RDA levels, and a regular aerobic exercise program is proposed.

Nutrition considerations in the neonatal extracorporeal life support patient

Extracorporeal life support (ECLS) is a type of heart-lung bypass commonly used to support neonates with life-threatening respiratory or cardiac failure. These patients are among the most critically ill patients in the neonatal intensive care unit and are at significant nutritional risk. Unfortunately, there is a paucity of literature regarding guidelines for nutrition support of the neonatal ECLS patient. The purpose of this article is to provide an overview of the indications, techniques, and complications of ECLS and to address the approach to nutrition support of these patients. Emphasis will be placed on issues unique to the neonatal ECLS patient.

Activation of retinal rod cGMP-gated channels: what makes for an effective 8-substituted derivative of cGMP?

Analogs of cGMP bearing diverse substituents at the C8 position of the guanine ring system have been shown to activate the cGMP-activated channel of retinal rods at concentrations lower than cGMP itself. In an effort to understand this behavior, we synthesized eight novel C8-substituted derivatives and tested their ability to activate channels in excised patches from salamander rod outer segments. We express the effectiveness of each analog as a ratio (in brackets) of the concentration required to open half of the channels in a patch to that required of 8-Br-cGMP, previously shown to be about 10 times more effective than cGMP. Five of the derivatives contained a thio substitution at C8: n-propylthio-cGMP [0.61], sulfoethylthio-cGMP [0.90], carboxyethylthio-cGMP [0.97], aminoethylthio-cGMP [2.8], and (trimethylamino)ethylthio-cGMP [8.5]. Three of the derivatives contained an amino substitution at C8: carboxyethylamino-cGMP [22], n-propylamino-cGMP [25], and aminoethylamino-cGMP [230]. The results indicate that thio-substitution at C8 produces more effective analogs than does amino-substitution, regardless of the chemical nature of the terminal functional group. Derivatives containing neutral and apolar tails opened channels at much lower concentrations than their positively-charged counterparts with the same C8 substituent. Analogs having negatively-charged tails were also more effective than those with positive charge but not quite as effective as those with neutral tails.(ABSTRACT TRUNCATED AT 250 WORDS)

Frequency and determinants of screening for breast cancer in primary care group practice

BACKGROUND

Many studies reporting the frequency of breast cancer screening have been based only on physician and patient surveys or on data from quality assurance studies and do not assess the reliability of information obtained from these various sources.

METHODS

To obtain more complete data we studied mammography performed in a 3-year period, 1988 through 1991, in 24 nonacademic primary care group practices by both auditing the medical records and obtaining questionnaire responses from 1819 women aged 53 to 62 years and from their 98 physicians in the nonmetropolitan Midwest.

RESULTS

Medical record data indicated that mammography was performed in all 3 years in 16.7%, in at least two of 3 years in 49.8%, and in at least one of 3 years in 81.7% of women. While patient reports of a family history of breast cancer, health insurance coverage for mammography, and greater annual household income were each significant predictors, a patient report that a clinic staff member had discussed mammography was the strongest predictor of greater frequency of mammography.

CONCLUSIONS

In this study of self-selected physicians and their patients, record-documented mammographic examinations were considerably more frequent than has been reported in some studies, but occurred at rates consistent with quality assurance data for the region. These data suggest that clinic staff initiatives with screening mammography have a large impact.

Specific labeling and permanent activation of the retinal rod cGMP-activated channel by the photoaffinity analog 8-p-azidophenacylthio-cGMP

Cyclic nucleotide-gated ion channels play a key role in visual excitation and a variety of other signaling pathways. The photoaffinity probe 8-p-azidophenacylthio-cGMP (APT-cGMP) has been developed for structural and functional studies of the cGMP-activated channel of retinal rod outer segments. Using this analog, we have demonstrated both specific labeling of the channel in a partially purified biochemical preparation from bovine rod outer segments and permanent activation of the channel current in excised membrane patches from salamander outer segments. After UV illumination, a 32P-labeled version of APT-cGMP was shown by SDS/PAGE and autoradiography to be covalently attached to the 63-kDa channel subunit. This incorporation was significantly reduced by 8-Br-cGMP but was not reduced by 5'-GMP. In patch-clamp experiments APT-cGMP was a potent activator of the channel; APT-cGMP typically opened half of the channels in a patch at a 10-fold lower concentration than cGMP. Exposure of membrane patches to UV light in the presence of APT-cGMP resulted in a persistent current observed in the absence of bath-applied nucleotide. This current increased with repeated exposure of the patch to both UV light and fresh APT-cGMP, approaching the maximum current originally evoked by saturating (500 microM) cGMP. At this point, addition of 500 microM cGMP caused a negligible increase in current. The persistent current had several other properties expected of current through cGMP-activated channels: it was outwardly rectifying; outward current was blocked > 90% by 2 mM internal Mg2+, whereas inward current was blocked much less efficiently; a low concentration of cGMP caused a larger increase in current atop a half-maximal persistent current than it did originally. We conclude that the persistent current was caused by the covalent tethering of cGMP moieties to channel binding sites, resulting in irreversible channel activation. APT-cGMP should prove useful for further studies of these and similar cGMP-binding sites and in the identification of unknown cGMP-binding proteins.

Comparison of motor vehicle damage documentation in emergency medical services run reports compared with photographic documentation

STUDY OBJECTIVE

To determine whether emergency medical services (EMS) run reports adequately document vehicle damage when compared with vehicle photographs by using a traffic accident scoring system.

DESIGN

A prospective study consisting of three phases: photographing motor vehicle collisions and collecting their respective EMS run reports, traffic accident damage score development, and comparison of photographs to the run reports by emergency medical technicians using the traffic accident damage score.

SETTING

Data were collected in North Carolina and Ohio from motor vehicle crashes to which nine different EMS squads responded during a three-year period.

TYPE OF PARTICIPANTS

EMS squads ranged from basic to paramedic levels of training.

MEASUREMENTS AND MAIN RESULTS

Three emergency medical technicians were unable to determine the area of vehicle damage in 48% and the severity of damage in 61% of the EMS run reports. In contrast, there were no instances in which all three emergency medical technicians were unable to determine both area and severity of damage from the photographs.

CONCLUSION

Most EMS run reports do not document vehicle damage adequately.

Interactions between divalent cations and the gating machinery of cyclic GMP-activated channels in salamander retinal rods

The effects of divalent cations on the gating of the cGMP-activated channel, and the effects of gating on the movement of divalent cations in and out of the channel's pore were studied by recording macroscopic currents in excised membrane patches from salamander retinal rods. The fractional block of cGMP-activated Na+ currents by internal and external Mg2+ as well as internal Ca2+ was nearly independent of cGMP concentration. This indicates that Mg2+ and Ca2+ bind with similar affinity to open and closed states of the channel. In contrast, the efficiency of block by internal Cd2+ or Zn2+ increased in proportion to the fraction of open channels, indicating that these ions preferentially occupy open channels. The kinetics of block by internal Ni2+, which competes with Mg2+ but blocks more slowly, were found to be unaffected by the fraction of channels open. External Ni2+, however, blocked and unblocked much more rapidly when channels were mostly open. This suggests that within the pore a gate is located between the binding site(s) for ions and the extracellular mouth of the channel. Micromolar concentrations of the transition metal divalent cations Ni2+, Cd2+, Zn2+, and Mn2+ applied to the cytoplasmic surface of a patch potentiated the response to subsaturating concentrations of cGMP without affecting the maximum current induced by saturating cGMP. The concentration of cGMP that opened half the channels was often lowered by a factor of three or more. Potentiation persisted after the experimental chamber was washed with divalent-free solution and fresh cGMP was applied, indicating that it does not result from an interaction between divalent cations and cGMP in solution; 1 mM EDTA or isotonic MgCl2 reversed potentiation. Voltage-jump experiments suggest that potentiation results from an increase in the rate of cGMP binding. Lowering the ionic strength of the bathing solution enhanced potentiation, suggesting that it involves electrostatic interactions. The strong electrostatic effect on cGMP binding and absence of effect on ion permeation through open channels implies that the cGMP binding sites on the channel are well separated from the permeation pathway.

Variation in a medical faculty's decisions to transfuse. Implications for modifying blood product utilization

Previous studies have identified disconcerting differences in transfusion practices among physicians. This article investigates decisionmaking on transfusion by a medical school faculty. One hundred fourteen physicians indicated their propensity to transfuse 24 hypothetical patients who varied systematically in four clinical cues. Physicians agreed with transfusion for a widely divergent number of these patients (mean, 14.6; standard deviation, 5.5; range, 0 to 24). Although the physicians agreed on the order of importance of the clinical cues, they varied significantly in the importance they empirically attributed to the cues and in their thresholds for transfusion. Aside from a slightly higher propensity to transfuse by general internists, differences in decisionmaking were not attributable to physician-based variables. The wide variability in decisionmaking among physicians in the face of agreement on the order of importance of clinical cues suggests that quality assurance programs, and guidelines that only list the cues that ought to influence transfusion decisions, have low potential to achieve blood-product conservation.

Functional regions of the inhibitory subunit of retinal rod cGMP phosphodiesterase identified by site-specific mutagenesis and fluorescence spectroscopy

In the dark, the activity of the cGMP phosphodiesterase (PDE) of retinal rod outer segments is held in check by its two inhibitory gamma subunits. Following illumination, gamma is rapidly removed from its inhibitory site by transducin, the G-protein of the visual system. In order to probe the functional roles of specific regions in the PDE gamma primary sequence, 10 variants of PDE gamma have been produced by site-specific mutagenesis and expression in bacteria and their properties compared to those of protein containing the wild-type bovine PDE gamma amino acid sequence. Three questions were asked about each mutant: What is its affinity for the alpha beta catalytic subunit of PDE? Does it inhibit catalytic activity? If so, can transducin relieve this inhibition? Binding to PDE alpha beta was determined directly using fluorescein-labeled gamma by measuring the increase in emission anisotropy that occurs when gamma binds to alpha beta. Inhibition of PDE alpha beta was measured by reconstitution of the gamma variants with gamma-free PDE generated by limited digestion with trypsin or endoproteinase Arg-C. Unlike trypsin, the latter enzyme did not remove PDE's ability to bind membranes and be activated by transducin, so that transducin activation of PDE containing specific gamma variants could be assayed directly. The results indicate that mutations in many regions of gamma affect its binding to alpha beta. A mutant missing the last five carboxy-terminal residues (83-87) was totally lacking in inhibitory activity. However, it still bound to PDE alpha beta tightly, although with a 100-fold lower dissociation constant (approximately 5 nM) than that of wild-type gamma (approximately 50 pM).(ABSTRACT TRUNCATED AT 250 WORDS)

Creating a substance abuse network in family medicine: lessons learned

Family practice was one of several primary care specialties awarded federal contracts in 1985 to survey substance abuse training needs. Family medicine has since excelled in creating a viable substance abuse network. Key events were the sponsorship of a fellowship program, the formation of the Society of Teachers of Family Medicine (STFM) Substance Abuse Working Group, and the working group's pursuit of externally funded projects. Tangible measures of the network's success include collective funding exceeding $7.3 million, an increase in the number of substance abuse activities at annual STFM conferences, and a nearly four-fold growth in the group's membership and collaborative publications. Key factors underlying the vitality of the network that may be generalizable include: 1) initial emphasis on training family physician faculty; 2) making optimal use of the existing administrative channels within STFM; 3) acquisition of external funding; 4) some continuity of core persons working together; 5) active networking within and outside family medicine; and 6) promotion of individual success.

Telephone triage by primary care physicians

To determine if experienced primary care physicians are more likely to reach correct decisions on the telephone than their less experienced colleagues, we asked 31 first-year and 29 third-year residents, 21 faculty, and 36 private practitioners in pediatrics and family practice to evaluate three pediatric patients via a telephone interview with a simulated mother and to decide whether each patient needed to be seen that evening. Compared with first-year residents, the third-year residents, faculty and private practitioners decided less frequently to see children who were not severely ill (P less than .05) or injured (P less than .01); however, less than half obtained histories considered adequate to rule out potential serious illnesses. Faculty did better than either residents or private practitioners in managing a severely dehydrated child; 100% of the faculty, but less than 60% of the residents or private practitioners, chose to see the patient promptly (P less than .001). More than one third of all residents and private practitioners reached inappropriate management decisions despite obtaining information that should have altered their decisions. In these simulations, experience in private practice was not associated with improved telephone management of very sick children. Faculty physicians appeared to be better able to identify severely ill children without inappropriately evaluating those who were less ill. In all three simulations, attainment of the correct decision appeared to be determined not by the number or type of questions asked, but rather by the physician's interpretation of the information collected.

Aflatoxin production via cross-feeding of pathway intermediates during cofermentation of aflatoxin pathway-blocked Aspergillus parasiticus mutants

Cofermentation of Aspergillus parasiticus strains (SRRC 163 and SRRC 2043) blocked at different steps in the aflatoxin B1 (AFB1) biosynthetic pathway in a synthetic liquid medium or on seeds (cottonseed, corn kernels, and peanuts) resulted in production of AFB1. Strain SRRC 2043 accumulated O-methylsterigmatocystin (OMST), a late precursor in AFB1 biosynthesis, whereas SRRC 163 accumulated averantin, an early precursor in the pathway. Strain SRRC 2043 secreted large amounts of OMST in culture relative to the amounts of several other pathway intermediates secreted into media (by other AFB1 pathway-blocked strains). AFB1 production occurred even when colonies of SRRC 163 and SRRC 2043 strains (producing no detectable AFB1) were grown together on an agar medium while physically separated from each other by a filter membrane (0.22-micron pore size). In addition, when mycelia of strain SRRC 163 were added to culture filtrates (containing no mycelia but containing secreted OMST) of strain SRRC 2043, AFB1 production occurred. The results suggested a chemical (rather than genetic) mechanism of complementation for AFB1 production between AFB1 pathway-blocked strains, since no mycelial contact was required between these strains for AFB1 production. The mechanism for chemical complementation involves secretion of OMST by SRRC 2043 and subsequent absorption and conversion of OMST to AFB1 by mycelia of strain SRRC 163.

Successful treatment of primary amebic meningoencephalitis

The fourth documented survivor of primary amebic meningoencephalitis, a young man with a history of waterskiing in a stagnant freshwater lake in northeastern Pennsylvania, is presented. Early consideration of this unusual diagnosis, based on historical factors (recent contact with warm fresh water), coupled with prompt aggressive therapy with high-dose amphotericin B is emphasized in achieving a successful outcome.

Variation in polygalacturonase production among Aspergillus flavus isolates

Pectinase production by Aspergillus flavus was determined by measuring clear zones formed around colonies stained with ruthenium red. Several isolates produced red zones instead of clear zones. Red zones were reproduced with pectinesterase and correlated with absence of specific polygalacturonases. Of 87 isolates tested, 15 produced red zones.

Race, nutritional status, and survival from breast cancer

The effects of nutritional status on differences in the survival of black and white women with breast cancer were studied in a cohort of 1,960 Georgia women diagnosed during 1975-1979. After data were adjusted for stage of disease, socioeconomic status, and other prognostic factors, poorer survival rates were shown in black women. Within each stage classification, lower levels of serum albumin and hemoglobin and higher relative body weight were more common among blacks and were independently associated with poorer survival. Among women with stage 3 disease, adjustment for these variables substantially reduced the excess mortality rate among blacks, suggesting that racial differences in survival may be partly explained by differences in nutritional status or extent of disease within stage.

Role of the nurse in treating trauma patients

Nurses, as the initial advanced life support providers at the scene of a disaster, can have great impact on the trauma patient's outcome. Below, their role at a disaster scene, with special emphasis on successful management of traumatized patients.

The Robustness of 2SLS Estimation of a Non-normally Distributed Confirmatory Factor Analysis Model

A Monte Carlo study was conducted to assess the robustness of the limited information two-stage least squares (2SLS) estimation procedure on a confirmatory factor analysis model with non-normal distributions. Full information maximum likelihood (FIML) methods were also used for a comparison. Both procedures were used to estimate model parameters, contingent upon a design utilizing two levels of model loadings (small versus large) over four different distribution conditions (normally distributed, small asymmetry, medium asymmetry, and large asymmetry, with kurtosis held constant). One hundred model replications were conducted to generate the study data. For the model and parameters studied, results indicated both estimators were robust with respect to moderate deviations from normality. Both estimators produced similar estimates across all conditions studied, thus providing a measure of high relative efficiency for the 2SLS procedure.