Search PubMed⌕ Search

Biomedical subjects

G D Harris

Publications and source records attributed to G D Harris.

At least 19 recordsLinked to original sources
PubMed1996

Maintaining normal intracranial pressure in a rabbit model during treatment of severe diabetic ketoacidemia.

Increased intracranial pressure (ICP) resulting in death or neurologic morbidity continues to complicate traditional management of diabetic ketoacidemia (DKA) in pediatric patients. When ICP or cerebrospinal fluid pressures have been measured, correction of hyperglycemia in animals and treatment of DKA in humans have consistently resulted in pathologic increases in ICP. We hypothesized that elevations in ICP can be minimized if changes in effective osmolality (Eosm) are controlled during treatment of DKA. During a six-hour study period, three groups of rabbits were studied: a normal control group of nondiabetic animals (Cnor, n = 10), a control group of animals with DKA (CDKA, n = 8), and an experimental group of animals with DKA (EDKA, n = 8). There was no significant difference between the two groups with DKA regarding pretreatment degree of dehydration, blood pressure, hyperglycemia, acidemia or ICP. During the treatment period, Cnor received maintenance fluids only. CDKA received insulin and an assumed volume of deficit (150 ml/kg) along with maintenance fluids and urinary output replacement with 0.45% NaCl. EDKA received insulin and one-half the volume of deficit calculated by the weight lost with 0.9% NaCl plus maintenance fluids. There was no significant difference between CDKA and EDKA regarding the rate at which DKA was corrected. While CDKA demonstrated a progressive and statistically significant increase in ICP, EDKA exhibited no such increase in ICP compared to normal, nondiabetic controls (Cnor) during treatment. Changes in Eosm during treatment in CDKA compared to Cnor and in CDKA compared to EDKA were significantly greater (p < .01), however, changes in EOSM in EDKA compared to Cnor were not significant. These data support the clinical observation that decreasing EOSM during treatment of DKA is associated with increased ICP and suggest that DKA can be treated effectively with i.v. fluids and insulin without increasing ICP.

Animals↗
PubMed1996

A multicenter prospective review of 640 endoscopic carpal tunnel releases using the transbursal and extrabursal chow techniques.

A prospective study involving eight institutions was performed, incorporating 640 cases of carpal tunnel release using a dual portal endoscopic technique. The original transbursal technique described by Chow was used in 110 cases (17%), and the modified extrabursal technique was used in 530 cases (83%). An overall complication rate of 11% was found in the patients in whom the transbursal technique was used, compared with 2.2% in the patients in whom the extrabursal technique was used. The return-to-work status was followed in 291 cases (199 non-worker's compensation cases and 92 worker's compensation cases). The worker's compensation patients returned to work in an average of 57 days, compared with 22 days for non-worker's compensation patients. This study suggests the extrabursal dual portal endoscopic technique is associated with fewer complications than the transbursal approach, and patients covered by worker's compensation return to work later than non-worker's compensation patients.

Adolescent↗
PubMed1994

Physiologic management of diabetic ketoacidemia. A 5-year prospective pediatric experience in 231 episodes.

OBJECTIVE: To determine whether gradual rehydration in moderate and severe diabetic ketoacidemia (DKA) can safely prevent untoward declines in calculated effective osmolality (Eosm) early in treatment and, hence, help prevent major central nervous system complications. DESIGN: Prospective study. SETTING: Three tertiary care hospitals. PATIENTS: Two hundred thirty-one consecutive episodes of DKA in 149 patients aged 10 months to 20 years admitted during a 5-year period. INTERVENTIONS: Insulin therapy in addition to rehydration using an estimated volume of deficit with planned administration over 48 hours; initial administration of rehydration solutions with an osmolality approximating that of the patient; and intensive patient monitoring. MEASUREMENTS: Mean lowest calculated Eosm (EosmL) during the first 24 hours of treatment; trend of the concentration of sodium in serum in the first 12 hours of treatment; comparison of pretreatment serum concentrations of glucose, urea nitrogen, and corrected sodium between mildly and very severely dehydrated patients; and patient outcome. RESULTS: A mean (+/- SD) EosmL of 285.8 +/- 10.5 mOsm/kg Nater and an increase in the concentration of sodium in serum in 90% of episodes were documented. There were statistically significant differences in serum concentrations of glucose, urea nitrogen, and corrected sodium in mildly vs very severely dehydrated patients. There were no deaths or near-death episodes. CONCLUSIONS: Management of moderate and severe DKA with a 48-hour planned rehydration is safe and prevents untoward declines in Eosm. Coupled with intensive monitoring, gradual rehydration can protect against life-threatening increases in intracranial pressure and brain herniation.

Adolescent↗
PubMed1994

Capillary refill?

Explore the source record for details and available documents.

Capillaries↗
PubMed1993

Brain osmoregulation during extreme and moderate dehydration in a rat model of severe DKA.

To determine if osmoprotective molecules accumulate in the brain during severe DKA with extreme (DKA-E) and moderate (DKA-M) dehydration, Fischer 344 rats (250-350g) were given STZ 45 mg/kg (i.p.) and allowed food and water ad lib. DKA-M received NaCl 77 mmol/L 60 ml/kg (i.p.) q 4 hrs. on day 2. All rats were anesthetized and sacrificed at 48 hrs. Half of each brain was used to measure water content (BWC) and half to measure Na+, K+, and organic osmoles by HPLC. Just prior to expiration, values for mean concentration of serum glucose (mmol/L) percent weight loss and median blood pH for DKA-E were 33.4, 19%, 6.98; for DKA-M, 16.8, 7.5% and 6.84, respectively. Means +/- SEM were compared by Student's t-test. Percent BWC was 76.3, 77.3 and 77.6 in DKA-E, DKA-M and normal controls, respectively (NS). Brain Na+ and K+ were increased in DKA-M compared to controls (p < .05) but not significantly different in DKA-E compared to controls. Of organic osmoles measured (umol/g wet weight) taurine was significantly increased (p < .01) in DKA-E and DKA-M (8.04 +/- .39 and 9.73 +/- .78, respectively) as compared to controls (5.92 +/- .35) as was myoinositol in DKA-E compared to controls (9.96 +/- .39 vs. 8.87 +/- .28) (p < .05) and urea in DKA-E as compared to controls (14.24 +/- 3.9 vs. 4.14 +/- .52) (p < .01). DKA-M were not significantly different for brain myoinositol or urea as compared to control animals. There was no significant difference in brain glutamine between either study group and controls. Preservation of brain water despite systemic dehydration can be partly explained by increased brain concentrations of osmoprotective molecules. Such adaption in the clinical setting of DKA warrants a cautious repair of dehydration and hyperosmolality.

Animals↗
PubMed1993

Correlation of primate red nucleus discharge with muscle activity during free-form arm movements.

1. We recorded from 239 neurons located in the magnocellular division of the red nucleus of four alert macaque monkeys. At the same time, we recorded electromyographic (EMG) signals from as many as twenty electrodes chronically implanted on muscles of the shoulder, arm, forearm and hand. We recorded EMG signals for periods ranging from several months to a year. 2. The monkeys were trained to perform three free-form food retrieval tasks, each of which activated all of the recorded muscles and most of the neurons. The 'prehension' task required simply that the monkey grasp a piece of food from a fixed point in space. The 'barrier' task required the monkey to reach around a small barrier to obtain the food, and the 'Kluver' task required that food be removed from small holes. During the prehension task, we found approximately equal numbers of neurons that were strongly active while the hand was being moved toward the target (70% of units), and while the food was being grasped (60%). Relatively few units were active as the hand was returned to the mouth (15%). 3. Data files of 1-2 min duration were collected while the monkey performed a single behavioural task. Whenever possible, we recorded files for all three tasks from each neuron. For each file we calculated long time-span analog cross-correlations (+/- 1.28 s) between instantaneous neuronal firing rate and each of the full-wave rectified, low-pass filtered EMG signals. We used the peak correlation and the time of the peak as two summary measures of the functional relation between modulation of neuronal activity and EMG. 4. The magnitude of the strongest correlations was between 0.4 and 0.5 (normalized to a perfect correlation of +/- 1.0). Distal muscles were the most frequently correlated, and extensors were more frequently correlated than flexors. For all monkeys, the lags for well correlated muscles were distributed broadly about a uni-modal value near 0 ms. Eighty five per cent of the correlations larger than or equal to 0.25 had peaks between -150 and 200 ms. 5. The activity of each neuron was represented in a muscle co-ordinate system by an n-dimensional 'functional linkage vector', each element of which was the peak correlation with one of n muscles. The vector for any given neuron points in a particular direction in muscle space, depending on the similarity between the activity of the neuron and the activity of each muscle.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1991

Capillary refilling (skin turgor) in the assessment of dehydration.

This study was undertaken to evaluate the usefulness of skin turgor or capillary refilling in estimating the degree of dehydration in infants with diarrhea. After initial standardization of the technique, capillary filling time was found to be more reproducible when measured in the fingernail bed after applying just the amount of pressure necessary to blanch the nail bed. Capillary refilling time in 30 normal infants 2 to 24 months of age was 0.81 +/- 0.31 seconds. Capillary filling time was then measured in 32 infants with diarrhea admitted to the hospital and correlated to the degree of dehydration as estimated from the difference in weight from the time of hospital admission to the weight after rehydration. A turgor time of 1.5 seconds or less was found to be indicative of a less than 50-mL/kg deficit or of a normal infant; 1.5 to 3.0 seconds suggests a deficit between 50 and 100 mL/kg, and more than 3 seconds suggests a deficit of more than 100 mL/kg.

Capillaries↗
PubMed1990

Minimizing the risk of brain herniation during treatment of diabetic ketoacidemia: a retrospective and prospective study.

We studied retrospectively, 219 episodes of diabetic ketoacidemia in 119 patients aged 13 months to 30 years, to determine the trend of the concentration of sodium in serum as glucose declined during treatment of uncomplicated episodes and of episodes with complications attributable to brain swelling. Of 20 complication, 13 were minor (headache only) and 7 major (death or near death). The concentration of sodium in serum failed to rise as that of glucose declined in 82 (54%) of 164 uncomplicated episodes and in 18 (95%) of 20 complicated episodes (p less than 0.01). Hence complications were more likely to occur among patients with a failure of the concentration of sodium to rise as glucose declined. Fifty-eight episodes of diabetic ketoacidemia in 40 patients aged 1 1/2 to 20 years were then studied prospectively on a 48-hour treatment plan to provide the volume of deficit evenly, with half the deficit of sodium in the first 42 hours. Sodium concentration in serum rose in 55 (95%) of 58 episodes as that of glucose declined. No patient had a major complication. We conclude that failure of the sodium concentration measured in serum to rise as glucose concentration declines is a marker for excessive administration of free water. An expanded repair period, with repair fluid containing an average of 125 mmol/L Na+ early in therapy, will usually protect against a downward trend in the concentration of sodium in serum and therefore against a rapid decline in effective serum osmolality. This regimen may be protective against near-death episodes and brain herniation during treatment.

Adolescent↗
PubMed1990

A comparison of two methods for facilitating clinical data integration by medical students.

Two important charting strategies to help students organize patients' data are Weed's problem-oriented medical record (POMR) and Russell's condition diagram (CD). The authors conducted the present study in 1987 to determine whether either was superior for clinical data integration. Sophomore medical students at The University of Texas Medical School at San Antonio indicated whether they preferred the POMR, the CD, or neither. They were then divided into three study groups according to their preferences, with the POMR and CD groups receiving 80 hours of training and the control group receiving only the standard preclinical training. Each student then examined a standardized patient and wrote an open-ended report about the patient's medical problem. After examining a second patient, students were asked to write a structured report providing information about each of ten components of diagnosis. Both the CD and the POMR groups scored numerically higher on the structured type of report than did the controls, but only the CD group scored significantly higher. The CD group also scored higher than did the POMR group on both types of report, but the differences were not statistically significant. This study indicates that the clinical reasoning of medical students can be enhanced by focused training in either the CD or the POMR methods. It suggests that the CD format may be particularly helpful for students with lower academic achievement.

Algorithms↗
PubMed1989

Preoperative spirometry before abdominal operations. A critical appraisal of its predictive value.

Preoperative spirometry is commonly ordered before abdominal surgery, with the goal of predicting and preventing postoperative pulmonary complications. We assessed the evidence for this practice with a systematic literature search and critical appraisal of published studies. The search identified 135 clinical articles, of which 22 (16%) were actual investigations of the use and predictive value of preoperative spirometry. All 22 studies had important methodological flaws that preclude valid conclusions about the value of screening preoperative spirometry. The available evidence indicates that spirometry's predictive value is unproved. Unanswered questions involve (1) the yield of spirometry, in addition to history and physical examination, in patients with clinically apparent lung disease; (2) spirometry's yield in detecting surgically important occult disease; and (3) its utility, or beneficial effect on patient outcome. Spirometry's full potential for risk assessment in the individual patient has not yet been realized.

Abdomen↗
PubMed1988

Characterization of inositol 1,4,5-trisphosphate-stimulated calcium release from rat cerebellar microsomal fractions. Comparison with [3H]inositol 1,4,5-trisphosphate binding.

The abilities of D-myo-inositol phosphates (InsPs) to promote Ca2+ release and to compete for D-myo-[3H]-inositol 1,4,5-trisphosphate [( 3H]Ins(1,4,5)P3) binding were examined with microsomal preparations from rat cerebellum. Of the seven InsPs examined, only Ins(1,4,5)P3, Ins(2,4,5)P3 and Ins(4,5)P2 stimulated the release of Ca2+. Ca2+ release was maximal in 4-6 s and was followed by a rapid re-accumulation of Ca2+ into the Ins(1,4,5)P3-sensitive compartment after Ins(1,4,5)P3, but not after Ins(2,4,5)P3 or Ins(4,5)P2. Ca2+ re-accumulation after Ins(1,4,5)P3 was also faster than after pulse additions of Ca2+, and coincided with the metabolism of [3H]Ins(1,4,5)P3. These data suggest that Ins(1,4,5)P3-induced Ca2+ release and the accompanying decrease in intraluminal Ca2+ stimulate the Ca2+ pump associated with the Ins(1,4,5)P3-sensitive compartment. That this effect was observed only after Ins(1,4,5)P3 may reflect differences in either the metabolic rates of the various InsPs or an effect of the Ins(1,4,5)P3 metabolite Ins(1,3,4,5)P4 to stimulate refilling of the Ins(1,4,5)P3-sensitive store. InsP-induced Ca2+ release was concentration-dependent, with EC50 values (concn. giving half-maximal release) of 60, 800 and 6500 nM for Ins(1,4,5)P3, Ins(2,4,5)P3 and Ins(4,5)P2 respectively. Ins(1,4,5)P3, Ins(2,4,5)P3 and Ins(4,5)P2 also competed for [3H]Ins(1,4,5)P3 binding, with respective IC50 values (concn. giving 50% inhibition) of 100, 850 and 13,000 nM. Comparison of the EC50 and IC50 values yielded a significant correlation (r = 0.991). These data provide evidence of an association between the [3H]Ins(1,4,5)P3-binding site and the receptor mediating Ins(1,4,5)P3-induced Ca2+ release.

Animals↗
PubMed1988

Free flap reconstruction of the lower back and posterior pelvis: indications, principles, and techniques.

Reconstructive microsurgery can be successfully applied to major defects of the lower back and posterior pelvis. When present, the superior and inferior gluteal vessels can be excellent free flap recipient vessels. However, if they are absent as a result of trauma or tumor ablation, a wrist carrier can be used to transfer large blocks of tissue in a staged procedure. Five patients are presented with challenging defects for which these techniques were used.

Adult↗
PubMed1987

Initial management of hand injuries in the emergency patient.

Failure to develop a proper routine for complete examination and documentation of the injured hand may result in the inability to make the proper diagnosis. Less than optimal treatment may result. Ultimately, the end result is unnecessary functional loss and, frequently, medical-legal difficulties. Initial emergency department management of acute hand is reviewed: recognition of surgical emergencies, proper initial treatment of tendon and nerve injuries, splinting, and record keeping are emphasized.

Emergencies↗
PubMed1987

The sural artery and vein as recipient vessels in free flap reconstruction about the knee.

The sural artery and vein were used successfully as recipient vessels in nine patients who required free flap reconstruction about the knee. The anatomy of the sural vessels and the potential advantages of their use as free flap recipients are reviewed and discussed. Indications include popliteal vessels that are absent or severely damaged, as determined by preoperative angiography. No anastomotic complications were encountered in this series, indicating that the sural artery and vein can be used successfully as recipient vessels.

Adolescent↗
PubMed1987

Accelerating recovery after trauma with free flaps.

Free flap versatility and dependability make the final result of microvascular reconstruction highly predictable. Free tissue transplantation should be considered as a primary treatment after trauma. The early use of free tissue transfer will result in fewer operations and a shortened duration of hospitalization in the initial post-trauma period.

Humans↗