Chronic centrifugation (hypergravity) disrupts the circadian system of the rat.

The present study was conducted to evaluate the response of rat deep body temperature (DBT) and gross locomotor activity (LMA) circadian rhythms to acute hypergravity onset and adaptation to chronic (14 day) hypergravity exposure over three gravity intensities (1.25, 1.5, and 2 G). Centrifugation of unanesthetized naive animals resulted in a dramatic acute decrease in DBT (-1.45, -2.40, and -3.09 degrees C for the 1.25, 1.5, and 2.0 G groups, respectively). LMA was suppressed for the duration of centrifugation (vs. control period); the percent decrease for each group on days 12-14, respectively, was 1.0 G, -15.2%, P = not significant; 1.25 G, -26.9%, P < 0.02; 1.5 G, -44.5%, P < 0.01; and 2.0 G, -63.1%, P < 0.002. The time required for DBT and LMA circadian rhythmic adaptation and stabilization to hypergravity onset increased from 1.25 to 2.0 G in all circadian metrics except daily means. Periodicity analysis detected the phenomenon of circadian rhythm splitting, which has not been reported previously in response to chronic hypergravity exposure. Our analysis documents the disruptive and dose-dependent effects of hypergravity on circadian rhythmicity and the time course of adaptation to 14-day chronic centrifugation exposure.

Body mass, energy intake, and water consumption of rats and humans during space flight.

Alteration of metabolism has been suggested as a major limiting factor to long-term space flight. In humans and primates, a negative energy balance has been reported. The metabolic response of rats to space flight has been suggested to result in a negative energy balance. We hypothesized that rats flown in space would maintain energy balance as indicated by maintenance of caloric intake and body mass gain. Further, the metabolism of the rat would be similar to that of laboratory-reared animals. We studied the results from 15 space flights lasting 4 to 19 d. There was no difference in average body weight (206 +/- 13.9 versus 206 +/- 14.8 g), body weight gain (5.8 +/- 0.48 versus 5.9 +/- 0.56 g/d), caloric intake (309 +/- 21.0 versus 309 +/- 20.1 kcal/kg of body mass per day), or water intake (200 +/- 8.6 versus 199 +/- 9.3 mL/kg of body mass per day) between flight and ground control animals. Compared with standard laboratory animals of similar body mass, no differences were noted. The observations suggested that the negative balance observed in humans and non-human primates may be due to other factors in the space-flight environment.

Rate controlling steps in fatty acid oxidation by unloaded rodent soleus muscle.

In response to decreased usage skeletal muscle undergoes an adaptive reductive remodeling due to the decrease in tension on the weight bearing components of the musculo-skeletal system. Accompanying a shift in fiber type is an increased reliance of carbohydrate metabolism and decreased reliance on fat for energy. These responses have been found with both space flight and ground based models of disuse atrophy including the chronically adapted rodent hind limb suspended (HLS) rat (1, 4-7, 10, 11). In addition, after space flight, the ability of soleus muscle homogenates to oxidize palmitate is decreased. We have previously shown that expression of the mRNA of enzymes involved in beta-oxidation is reduced in the soleus muscle of HLS rats. At the same time mRNA expression of enzymes involved in glycolysis was increased. This study extends these observations to address the question of whether the decrease in beta-oxidation is caused by a reduction in the capacity of the pathway to oxidize fat or the regulation is effected before fatty acids enter the mitochondria, i.e. the reduced capacity of the fatty acid oxidation pathway is because less fat is available for oxidation. The two key steps involved in fatty acid uptake into the cells are lipoprotein lipase and the transport of the free fatty acids produced by lipoprotein lipase into the cell via the carnitine acyltransferase system.

Collaboration with school nurses: improving the effectiveness of tuberculosis screening.

OBJECTIVE: To compare tuberculosis skin test (TST) reading rates between children whose tests were read by school nurses following specific requests by physicians and those who relied on their parents to get their tests read, either at school or at the physician's office. DESIGN: A randomized controlled trial. SETTING: An urban hospital-based pediatric practice. PARTICIPANTS: Healthy low-income Hispanic and African American children aged 5 to 17 years whose physicians ordered TSTs at their routine physical examinations. Subjects attended 1 of 68 public schools. Nurses at these schools were willing to read student TSTs, and received instructions about how to read and report the results back to the physician's office. INTERVENTION: Subjects were randomized to a control group (routine TST placement, with no physician-to-school nurse communication) or to an intervention group (routine TST placement, with physician-to-school nurse communication). MAIN OUTCOME MEASURES: Tuberculosis skin test reading rates between the 2 groups were compared. Impediments to TST reading and reporting were investigated. RESULTS: One hundred thirty-four children were enrolled, 54 (40%) in the control group and 80 (60%) in the intervention group. More patients in the intervention group had their TSTs read by 72 hours compared with those in the control group (74 [92%] vs 30 [56%]; P<.001). The low reading rate in the control group was best attributed to communication failures. CONCLUSION: Systematic collaboration with school nurses can increase TST reading rates.

Hormonal modulation of food intake in response to low leptin levels induced by hypergravity.

A loss in fat mass is a common response to centrifugation and it results in low circulating leptin concentrations. However, rats adapted to hypergravity are euphagic. The focus of this study was to examine leptin and other peripheral signals of energy balance in the presence of a hypergravity-induced loss of fat mass and euphagia. Male Sprague-Dawley rats were centrifuged for 14 days at gravity levels of 1.25, 1.5, or 2 G, or they remained stationary at 1 G. Urinary catecholamines, urinary corticosterone, food intake, and body mass were measured on Days 11 to 14. Plasma hormones and epididymal fat pad mass were measured on Day 14. Mean body mass of the 1.25, 1.5, and 2 G groups were significantly (P < 0.05) lower than controls, and no differences were found in food intake (g/day/100 g body mass) between the hypergravity groups and controls. Epididymal fat mass was 14%, 14%, and 21% lower than controls in the 1.25, 1.5, and 2.0 G groups, respectively. Plasma leptin was significantly reduced from controls by 46%, 45%, and 65% in the 1.25, 1.5, and 2 G groups, respectively. Plasma insulin was significantly lower in the 1.25, 1.5, and 2.0 G groups than controls by 35%, 38%, and 33%. No differences were found between controls and hypergravity groups in urinary corticosterone. Mean urinary epinephrine was significantly higher in the 1.5 and 2.0 G groups than in controls. Mean urinary norepinephrine was significantly higher in the 1.25, 1.5 and 2.0 G groups than in controls. Significant correlations were found between G load and body mass, fat mass, leptin, urinary epinephrine, and norepinephrine. During hypergravity exposure, maintenance of food intake is the result of a complex relationship between multiple pathways, which abates the importance of leptin as a primary signal.

No effect of hypergravity on adult rat ventral horn neuron size or SDH activity.

BACKGROUND: Spaceflights of short duration (approximately 2 wk) result in adaptations in the size and/or metabolic properties of a select population of motoneurons located in the lumbosacral region of the rat spinal cord. A decrease in succinate dehydrogenase (SDH, an oxidative marker enzyme) activity of moderately sized (500-800 microm2) motoneurons in the retrodorsolateral region of the spinal cord (L6) has been observed after a 14-d flight. HYPOTHESIS: Our hypothesis was that exposure to short-term hypergravity would result in adaptations in the opposite direction, reflecting a continuum of morphological and biochemical responses in the spinal motoneurons from zero gravity to hypergravity. METHODS: Young, male rats were centrifuged at either 1.5 or 2.0 G for 2 wk. The size and SDH activity of a population of motoneurons in the retrodorsolateral region of the spinal cord (L5) were determined and compared with age-matched rats maintained at 1.0 G. The absolute and relative (to body weight) masses of the soleus, gastrocnemius, adductor longus and tibialis anterior muscles were compared among the three groups. RESULTS: There were no effects of either hypergravity intervention on the motoneuron properties. Rats maintained under hypergravity conditions gained less body mass than rats kept at 1.0 G. For the 1.5 and 2.0 G groups, the muscle absolute mass was smaller and relative mass similar to that observed in the 1.0 G rats, except for the adductor longus. The adductor longus absolute mass was similar to and the relative mass larger in both hypergravity groups than in the 1.0 G group. CONCLUSIONS: Our hypothesis was rejected. The findings suggest that rat motoneurons are more responsive to short-term chronic exposure to spaceflight than to hypergravity conditions.

Isolated congenital malabsorption of folic acid in a male infant: insights into treatment and mechanism of defect.

An instructive case of isolated congenital folate malabsorption provides insight into the understanding of this rare disease. Folate loading tests with both timed serum and cerebrospinal fluid folate determinations suggest that both of the two mechanisms involved in gastrointestinal folate absorption are defective in this condition.

Size constraints of telemeters in rats.

This study was designed to determine the maximum-size subcutaneous telemeter that would enable long-term and multichannel data collection in a 170-g rat for 90 days. In phase 1, rats with implants weighing 5 (2.5 cm3), 15 (7.5 cm3), 25 (12.5 cm3), 35 (17.5 cm3), or 45 (22.5 cm3) g were compared with sham-operated (SOC) and nonoperated (NOC) control animals. Severe skin lesions, seromas, and lower growth rates were observed in rats having implants >/=35 g. Thus, in phase 2, rats implanted with 23.5 g (17.5 cm3; 11-g active telemeter and 12.5-g implant) were compared with rats implanted with 11 g (6 cm3; telemeter only) and with the SOC and NOC groups. No differences were found among implanted groups in mean arterial pressure (MAP), heart rate (HR), subcutaneous temperature, or spontaneous activity under standard housing conditions. All groups were more active and had a higher MAP during the dark than the light phase of the daily cycle. During 2 h of cold exposure (3 degreesC), both telemetered groups exhibited similar changes in HR, MAP, temperature, and activity levels. Adrenal glands were larger in the 23.5-g group (51 +/- 1.6 mg) than in the SOC (46 +/- 1.0 mg) and the NOC groups (41 +/- 2.0 mg). No other significant differences were found in organ, muscle, or bone weights. These data verify the feasibility of using 23.5-g (17.5 cm3) subcutaneous telemeters for chronic recordings in young adult rats.

The role of autologous blood transfusion in adolescents undergoing spinal surgery.

STUDY DESIGN: A prospective study of 147 consecutive patients undergoing spinal surgery who were analyzed for response to an effect of an offered autologous blood program. OBJECTIVES: Analysis of the impact of the autologous program within a comprehensive blood conservation philosophy toward the reduction in the use of homologous blood. METHODS: Each patient was prescreened by the autologous program for inclusions and ability. Physical parameters were recorded as were predonation and postdonation hemoglobin levels. The volume of each donation and the number of autologous and homologous units transfused and total operating blood loss were recorded as were complications during donation and transfusion. RESULTS: One hundred sixteen of the original one hundred forty-seven patients participated in the program and donated between 150 and 1900 ml of blood during the preoperative period. Of these, 35 patients weighed 45 kg or less. Diagnoses included 97 cases of idiopathic scoliosis and the remainder had spinal deformities of other causes. Of the entire group, 13 patients (11%) received homologous blood transfusion, 7 of these patients had diagnoses other than idiopathic scoliosis. CONCLUSIONS: In this study of 116 patients, 89% of the spinal surgeries were successfully completed using only autologous blood. This compared favorably with a historical control group in which 60% of the patients required homologous blood transfusion. It is concluded that the use of autologous blood donation combined with other blood conservation techniques has significantly lessened the need for homologous transfusion.

Influence of simulated microgravity on the exercise performance of Fischer 344 rats.

Measurements from mission specialists after space flights or from subjects subjected to head down tilt experiments have demonstrated a decrease in exercise performance. Similar decreases have been reported for rats that have participated in simulated microgravity studies using the head down-tail suspended method of Morey-Holton (HDS). Because it is unclear whether older animal populations would exhibit similar responses, we undertook a HDS study with Fischer 344 male rats.

Chevron osteotomy for bunionette.

Numerous procedures have been described for the surgical treatment of symptomatic bunionettes. We describe the technique, results, and follow-up of patients treated with a chevron osteotomy of the distal fifth metatarsal. This surgical approach to the treatment of bunionette is presented as a viable alternative to other surgical procedures. Sixteen distal fifth metatarsal chevron osteotomies were performed on 12 patients. Follow-up was from 15 months to 6 years, with an average follow-up of 3.2 years. A 100-point scoring system was devised and the average score improved from 44 points before surgery (range 20-65) to 91 points after surgery (range 65-100). There was one complication of a transfer metatarsalgia. The overall results were good to excellent, except for the transfer metatarsalgia, which was rated as fair. We have used the procedure in a laterally deviated, plantar metatarsal. There is concern that alternatives be used in a laterally deviated, plantarflexed fifth metatarsal. We have continued to use the chevron osteotomy with this condition.

Long distance travel by children for tonsillectomy: experience of the ORL department at Princess Alexandra Hospital (PAH), Royal Air Force, Wroughton, Swindon.

An audit was carried out to assess the acceptability of long distance travel for elective tonsillectomy and adenoidectomy. Seventy nine children travelled 70 miles with their father or mother to P.A.H. from Mid Glamorgan where the E.N.T. waiting list delay for tonsillectomy was some two years. Most of the families who were offered the travel arrangements agreed and from the results of the questionnaires answered by the first 50 families, it was shown to be a successful exercise as both the children and parents were very happy with the arrangements and there were no complications.

Demonstration of myoglobin and CK-M in myocardium. Comparison of five fixation methods and three immunohistochemical techniques.

The results of immunohistochemical staining vary depending on the tissue, fixative, antigen-antibody system, and immunohistochemical staining methods used. The purpose of this study was to evaluate the effect of different methods of fixation, different antigen-antibody systems, and different immunohistochemical methods on immunohistochemical staining of myocardium. Samples of normal fresh canine myocardium from six dogs were fresh frozen and fixed in 10% neutral buffered formalin, Bouin's, Bayley's and Carnoy's fixatives. Immunohistochemical staining for myoglobin and creatine kinase M was performed using the ABC (avidin-biotin complex) and indirect peroxidase-antiperoxidase (PAP) techniques. Tissues fixed in formalin showed the most intense specific staining for both antigens with the least background and nonspecific staining. All other fixation methods and frozen section techniques gave a more variable degree of specific positive staining and substantial background staining and/or nonspecific staining. ABC and PAP techniques gave similar results with both antigen-antibody systems and with each fixation method. Thus, no differences in specificity or sensitivity were observed between ABC and PAP techniques. Differences in staining intensity and pattern were related primarily to differences in fixation methods.

Distribution of LDH-1 in normal, ischemic, and necrotic myocardium. An immunoperoxidase study.

To study the distribution of lactate dehydrogenase (LDH-1) (H4) in normal, ischemic, and necrotic myocardium using the peroxidase-antiperoxidase technic, the authors studied formalin-fixed paraffin-embedded sections of human (n = 11) and canine (n = 28) myocardium. All normal control myocardium showed positive immunostaining for LDH-1 (H4). In infarcts 10 hours or more old, the histologically necrotic myocardium (by triphenyl tetrazolium chloride staining) (TTC) showed markedly diminished immunostaining. In 24-dogs ischemia was induced in a closed-chest model using a balloon-tipped catheter inflated in the left anterior descending coronary artery. In dogs with 3 hours or more of occlusion, myocardium that was necrotic by TTC staining, light and/or electron microscopy, showed diminished staining for LDH-1, while normal, control myocardium stained intensely. In four dogs, ischemia was induced by a controlled perfusion apparatus by which left main coronary flow was reduced by 50%. Ischemia without necrosis was documented by demonstration of glycogen loss with no light or electron microscopic evidence of necrosis. These ischemic fibers stained intensely for LDH-1, as did controls. Thus, by immunoperoxidase staining, LDH-1 can be demonstrated in normal human and canine myocardium. In experimental models of ischemia in dogs, tissue that was ischemic but not necrotic showed no diminished staining. LDH-1 loss can be detected in necrotic myocardium as early as 3 hours after coronary artery occlusion.