The recent expansion of Pluto's atmosphere

Stellar occultations--the passing of a relatively nearby body in front of a background star--can be used to probe the atmosphere of the closer body with a spatial resolution of a few kilometres (ref. 1). Such observations can yield the scale height, temperature profile, and other information about the structure of the occulting atmosphere. Occultation data acquired for Pluto's atmosphere in 1988 revealed a nearly isothermal atmosphere above a radius of approximately 1,215 km. Below this level, the data could be interpreted as indicating either an extinction layer or the onset of a large thermal gradient, calling into question the fundamental structure of this atmosphere. Another question is to what extent Pluto's atmosphere might be collapsing as it recedes from the Sun (passing perihelion in 1989 in its 248-year orbital period), owing to the extreme sensitivity of the equilibrium surface pressure to the surface temperature. Here we report observations at a variety of visible and infrared wavelengths of an occultation of a star by Pluto in August 2002. These data reveal evidence for extinction in Pluto's atmosphere and show that it has indeed changed, having expanded rather than collapsed, since 1988.

A comparative mechanical analysis of the pointe shoe toe box. An in vitro study

Dancing en pointe requires the ballerina to stand on her toes, which are protected only by the pointe shoe toe box. This protection diminishes when the toe box loses its structural integrity. The objectives of this study were 1) to quantify the comparative structural static and fatigue properties of the pointe shoe toe box, and 2) to evaluate the preferred shoe characteristics as determined by a survey of local dancers. Five different pointe shoes (Capezio, Freed, Gaynor Minden, Leo's, and Grishko) were evaluated to quantify the static stiffness, static strength, and fatigue properties (cycles to failure) of the shoes. Under axial loading conditions, the Leo's shoe demonstrated the highest stiffness level, and the Freed shoe exhibited the least strength. Under vertical loading conditions, the Leo's and Freed shoes demonstrated the highest stiffness levels, and the Gaynor Minden and Freed shoes exhibited the highest strength. Fatigue testing highlighted the greatest differences among the five shoes, with the Gaynor Minden demonstrating the highest fatigue life. Dancers rated the top five shoe characteristics, in order of importance, as fit, comfort, box/platform shape, vamp shape, and durability and indicated that the "best" shoe is one that "feels right" and permits artistic maneuvers, not necessarily the strongest or most durable shoe.

Biochemical pathway mediating the response of bone cells to capacitive coupling

Rat calvarial bone cells or mouse MC3T3-E1 bone cells subjected to a capacitively coupled electric field of 20 mV/cm consistently showed significant increases in cellular proliferation as determined by deoxyribonucleic acid content. Verapamil, a membrane calcium channel blocker; W-7, a calmodulin antagonist; indocin, a prostaglandin synthesis inhibitor; or bromophenacyl bromide, a phospholipase A2 inhibitor, each at a concentration that did not interfere with cell proliferation in control cultures, inhibited proliferation in those cultures subjected to the electric field. In contrast, neomycin, an inhibitor of the inositol phosphate cascade, did not inhibit this electrically induced cellular proliferation. Prostaglandin E2 production also was increased significantly with electrical stimulation, and this increase was inhibited by verapamil or indocin but not by neomycin. Thus, the data suggest that the signal transduction mediating the proliferative response of cultured bone cells to a capacitively coupled field involved transmembrane calcium translocation via voltage gated calcium channels, activation of phospholipase A2, and a subsequent increase in prostaglandin E2. Increases in cytosolic calcium and activated calmodulin are implied. The inositol phosphate pathway, unlike its dominant role in signal transduction in mechanically stimulated bone cells, does not appear to play a role in signal transduction in the proliferative response of bone cells to electrical stimulation.

Ultrasonographic diagnosis of recurrence after excision of an interdigital neuroma

We retrospectively reviewed the records of 20 patients (21 feet) with previous interdigital neuroma resections and symptoms suggestive for, but not diagnostic of, recurrent neuroma. Sonography was performed when clinical findings supplemented by local anesthetic block did not conclusively confirm the presence of recurrent neuroma. Studies performed in 13 patients (14 feet) were positive for recurrent neuromas. Three studies were indeterminate. The remaining four studies were negative for recurrent neuroma. The ultrasound studies were performed at an average of 19.2 months (range, 2-82 months) after the resection. Nine patients with 11 previous interdigital neuromas underwent ultrasonographic examination of the forefoot and subsequent revision neuroma resection. At surgery, gross and histologic findings were consistent with recurrent neuroma in 10 of 11 cases; one patient was found to have metatarsal-phalangeal synovitis. Ultrasonography appears to be a useful means for confirming neuroma recurrence in patients with symptoms after interdigital neurectomy when the diagnosis is not clear on physical examination.

Salvage of pseudoarthrosis after tibiotalar arthrodesis

We retrospectively reviewed the treatment of a selected group of 23 patients with pseudoarthrosis after ankle arthrodesis who underwent revision arthrodesis at an average of 1.7 years (range, 0.3-17.0 years) after the initial, unsuccessful procedure. Fourteen patients underwent isolated revision tibiotalar arthrodesis, and 9 had an additional hindfoot arthrodesis (7 tibiotalocalcaneal, 2 pantalar) performed at the time of the procedure. Rigid internal fixation with screws was performed when possible, and, in patients with poor bone quality, an external fixator was used. Autogenous bone grafting was used in 14 patients where bone loss was present. Twenty-one of 23 patients had successful union (average, 14 weeks; range, 6-48 weeks). Two patients underwent successful arthrodesis but had persistent pain from reflex sympathetic dystrophy. Overall, 19 of 23 patients were satisfied with the surgery. We conclude that revision arthrodesis for tibiotalar pseudoarthrosis is a worthwhile procedure.

The biochemical pathway mediating the proliferative response of bone cells to a mechanical stimulus

Calvarial bone cells of rats were subjected to either a cyclic biaxial strain of 0.17 per cent (1700 microstrain) or a hydrostatic pressure of 2.5, five, or ten pounds per square inch (17.2, 34.5, or sixty-nine kilopascals). The frequency was held constant at one hertz for both types of mechanical stimulation. When cultured bone cells that had been subjected to a cyclic biaxial strain for two hours were harvested twenty-two hours later, it was found that the level of prostaglandin E2 had increased significantly (p < 0.01) as had cellular proliferation (p < 0.01), as indicated by the incorporation of [3H]-thymidine. The addition to the medium of indomethacin, an inhibitor of prostaglandin synthesis, at a ten-micromolar concentration significantly inhibited (p < 0.01) the increase in prostaglandin E2 synthesis but had no effect on the strain-induced increase in cellular proliferation, as indicated by the incorporation of [3H]-thymidine. Twenty-four hours after exposure to the same cyclic biaxial strain for thirty seconds, other cultured bone cells showed a significant increase in the level of cytoskeletal calmodulin (p < 0.05) and in the DNA content (p < 0.05). N-(6-aminohexyl)-5-chloro-1-naphthalene-sulfonamide (W-7), a calmodulin antagonist, was added to the medium at a one-micromolar concentration, which had been shown to have no effect on the increase in the DNA content of control cells; W-7 completely blocked the increase in the level of cytoskeletal calmodulin and in the DNA content in the cells that were subjected to a cyclic biaxial strain. The bone cells subjected to a hydrostatic pressure showed a dose-dependent increase in the concentration of cytosolic Ca2+, as measured with Fura 2-AM, a fluorescent indicator of intracellular calcium. With a pressure of ten pounds per square inch (sixty-nine kilopascals), the increase in the concentration of cytosolic Ca2+ was nearly eight times greater than that at 2.5 pounds per square inch (17.2 kilopascals) (126 +/- 15.2 compared with 16 +/- 8.0 nanomolar, mean and standard deviation). The addition to the medium of neomycin, an inhibitor of the inositol phosphate cascade, at a ten-millimolar concentration completely blocked the increase in the concentration of cytosolic Ca2+ in these cells; this concentration of neomycin had been shown to have no effect on proliferation in control bone cells. There was also a dose-dependent relationship between the duration of the stimulus and the cellular proliferation. Remarkably, one cycle of pressure at ten pounds per square inch (sixty-nine kilopascals) and a frequency of approximately one hertz produced a 57 per cent increase in the incorporation of [3H]-thymidine at twenty-four hours (p < 0.001). From these findings, we hypothesized that the inositol phosphate cascade-cytosolic Ca(2+)-cytoskeletal calmodulin system plays a dominant role in the signal transduction of a mechanical stimulus into increased proliferation of bone cells, at least under the conditions reported here.

Langerhans' cell histiocytosis of the spine in children

Between May 1972 and December 1991, 58 children were seen in the authors' institution for treatment of Langerhans' cell histiocytosis. Of these, 15 children (7 males, 8 females) had biopsy-proven Langerhans' cell histiocytosis with vertebral involvement. The average age at presentation was 6.4 years (range, 0.2-13.3 years). At presentation, 8 patients had involvement of a single vertebra and 4 had involvement of multiple vertebrae. Nine patients had extraspinal skeletal involvement. Two patients had visceral involvement. Currently, 13 patients have had >2 years followup (average, 8.9 years; range, 2-21 years). None of these patients had clinical evidence of disease at the latest encounter. This group of patients with Langerhans' cell histiocytosis with vertebral involvement has fared well. Most patients have had involvement of multiple vertebrae and many have had extraspinal bony involvement as well. There was a great deal of variability in the extent of collapse and reconstitution of vertebral height, and the amount of reconstitution did not correlate with patient age.

Distraction osteogenesis for congenitally short lesser metatarsals

Six lesser metatarsal lengthening procedures were performed in three patients using a miniature external fixator to perform distraction osteogenesis. The metatarsals were lengthened an average of 15.5 mm. The external fixator was left in place for an average of 15.5 weeks, with additional time in a cast or cast shoe. Complications included five occurrences of infection, two cases of premature healing of the osteotomy, one nondisplaced fracture through the new bone formation, and hypertrophic granulation at a pin site. While all metarasals were successfully lengthened, two rays (one patient) had symptomatic stiffness at the metatarsophalangeal joint with continued metatarsalgia.

Tympanic electrocochleography for diagnosis of Menière's disease

OBJECTIVE

Tympanic electrocochleography (ECOG) is a noninvasive technique for recording cochlear potentials with an electrode placed on the tympanic membrane. Electrocochleography is used clinically in the evaluation of patients for endolymphatic hydrops. This study was undertaken to obtain normative data for ECOG responses to clicks and tone bursts and to determine clinical indicators that result in high test specificities.

DESIGN

Three cochlear potentials were measured; the eighth nerve compound action potential, the cochlear microphonic, and the summating potential. The subjects were 53 normal hearing adults with negative histories for symptoms of Menière's disease. The ECOG responses were measured with a silver wire-rayon wick electrode that was placed on the tympanic membrane under direct microscopic visualization. Stimuli were condensation, rarefaction, and alternating polarity clicks and 1- and 2-kHz tone bursts.

RESULTS

Measures that appear to be useful in the evaluation of endolymphatic hydrops include the summating potential to action potential ratio, action potential latency difference to condensation and rarefaction clicks, and the tone-burst-evoked summating potential. Relationships among these measures were investigated, and abnormal criteria were determined that result in test specificities of 95%.

CONCLUSIONS

Menière's disease is viewed as a progressive disease in which ECOG characteristics vary with the disease state. Cases are presented to illustrate ECOG responses in various stages of the disease. The normative data presented in this article are useful for the detection of Menière's disease in its early stages.

Magnetic resonance imaging for the diagnosis of osteomyelitis in the diabetic patient with a foot ulcer

Twenty-seven diabetic patients (12 males and 15 females) with clinically suspected osteomyelitis complicating soft tissue infection of the foot underwent 29 magnetic resonance imaging studies of the suspected lesion. Of these patients, 26 had plain film radiographs, 11 had technetium bone scanning, and 12 had indium-labeled leukocyte scintigraphy performed within 2 weeks of the magnetic resonance imaging. Definitive diagnosis of the presence or absence of osteomyelitis was obtained on the basis of surgical findings, histological evidence, or resolution with nonoperative therapy. Magnetic resonance imaging was 90% accurate (sensitivity 77%, specificity 100%) in the diagnosis of osteomyelitis in this patient population. Technetium bone scan was 45% accurate (sensitivity 100%, specificity 25%); indium-labeled leukocyte scintigraphy was 50% accurate (80% sensitivity, 29% specificity); and plain film roentgenography was 73% accurate (60% sensitivity, 81% specificity). Magnetic resonance imaging is a powerful, noninvasive tool for determining the presence or absence of osteomyelitis in the patient with a diabetic foot ulcer.

Diagnoses and staging. Osteomyelitis and prosthetic joint infections

The diagnoses of osteomyelitis and prosthetic joint infections are usually made on the basis of clinical, laboratory, and radiographic examination. The diagnostic studies presently employed to diagnosis and assess osteomyelitis and prosthetic joint infections are described. A universally applied classification system for stratifying osteomyelitis and prosthetic joint infection would provide a framework for the evaluation of medical and surgical treatment efficacy. Such a system would enable treatment results to be compared among institutions. Staging systems currently being used are described.

Protein-restricted diets in diabetic nephropathy

Low-protein diets in nondiabetic renal failure may slow the progressive loss of renal function in some patients, but few studies have detailed the nutritional consequences of these diets in patients with diabetic nephropathy. We studied 7 patients with insulin-dependent diabetes mellitus and chronic renal insufficiency [mean +/- SEM creatinine clearance (S, U): 28.3 +/- 6.5 ml/min (0.47 +/- 0.11 ml/s x 1.73/A)] for 15 weeks who were prescribed a diet of 0.6 g protein/kg ideal body weight. Midarm muscle circumference (24.1 +/- 1.8 at onset vs. 24.5 +/- 1.5 cm at completion), triceps skinfold thickness (21.6 +/- 3.1 vs. 21.0 +/- 1.5 mm), body weight (71.8 +/- 4.1 vs. 71.2 +/- 4.6 kg), and serum albumin [3.0 +/- 0.1 vs. 3.2 +/- 0.1 g/dl (30 +/- 1 vs. 32 +/- 1 g/l)] remained stable. Based on urinary nitrogen excretion, diet diaries overestimated the degree of dietary protein restriction; there was good adherence to the diet as evidenced by a reduction in urinary urea nitrogen (average 32%). Blood glucose control was maintained despite increased carbohydrate intake. On average, creatinine clearance did not change significantly, but proteinuria diminished slightly (1.8 +/- 0.2 vs. 1.5 +/- 0.6 g/day). These results indicate that 0.6 g/kg/day protein diets did not cause protein depletion in insulin-dependent diabetic patients. Longer-term studies are indicated to assess more fully the efficacy of these dietary regimens in reducing proteinuria or benefiting diabetic nephropathy.

One- and two-dimensional NMR relaxation studies of dynamics and structure in bile salt-phosphatidylcholine mixed micelles

A series of one- and two-dimensional 1H-NMR relaxation measurements has been conducted on simple and mixed micellar aggregates of taurocholate, diphenylvaleroylphosphatidylcholine (diPVPC) and egg yolk phosphatidylcholine (egg PC). The results are interpreted to provide structural and dynamic comparisons between micelles and vesicles, between phospholipids of varying chain length, and between different lipid components within the same micellar aggregate. Both chemical shift changes and two-dimensional nuclear Overhauser effect cross peaks suggest direct interaction of taurocholate and PC chemical sites, although the latter observations may also be accounted for by PC-PC interactions. These experiments demonstrate the promise of NMR relaxation techniques for investigations of molecular organization in model substrate for lipolytic enzymes.

Isolation and sequencing of a cDNA clone homologous to the v-sis oncogene from human endothelial cells

A clone containing the 3' end of the mRNA for the human c-sis gene (homologous to the B chain of platelet-derived growth factor) was isolated from a cDNA library derived from human umbilical vein endothelial cells and then sequenced. The analysis of possible translation products in all three reading frames indicated that the A chain of platelet-derived growth factor was not coded for within the 3' end of the c-sis mRNA. The 3' end of the mRNA for c-sis is contained in or adjacent to exon 6.

Nutritional status of diabetic and nondiabetic patients after renal transplantation

To assess whether there was improvement in the nutritional status of Type I insulin-dependent diabetics treated with renal transplantation as compared with dialysis, 24 diabetics and 21 nondiabetics were studied 22.6 +/- 23.8 mo after transplantation. Nutritional assessment included weight, height, triceps skinfold thickness, midarm muscle circumference (MAMC), serum albumin, and transferrin. Mean age of the 28 males and 17 females was 37.1 +/- 9.4 yr. Weight of diabetics increased from 55.6 +/- 8.4 kg to 61.5 +/- 9.5 kg (p less than 0.05); weight for height, from 81 +/- 8% to 95 +/- 9% (p less than 0.001); and serum albumin, from 3.8 +/- 0.5 gm/dl to 4.3 +/- 0.4 gm/dl (p less than 0.001). Weight also increased significantly in nondiabetics from 64.5 +/- 10.5 kg to 72.1 +/- 13.5 kg (p = 0.05); weight for height, from 96 +/- 15% to 108 +/- 16% (p less than 0.05); but not albumin, 4.1 +/- 0.7 gm/dl to 4.4 +/- 0.6 gm/dl (p greater than 0.05). Serum transferrin was 210 +/- 62 mg/dl in diabetics and 226 +/- 52 mg/dl in nondiabetics. Forty-two percent of diabetics and 29% of nondiabetics had a MAMC less than 5th percentile, indicating protein-calorie malnutrition. Results suggest a significant improvement in nutritional status after transplantation in both diabetics and nondiabetics, but particularly in the diabetic group.

Benign intracranial hypertension and facial diplegia

Benign intracranial hypertension (BIH) may occasionally be associated with false localizing cranial nerve palsies. Abducens nerve palsies reportedly occur in 10% to 60% of patients with BIH, whereas other cranial nerve palsies occur much less frequently. We treated a woman with benign intracranial hypertension and facial diplegia who showed complete resolution of her cranial nerve palsies after control of her elevated intracranial pressure with a lumboperitoneal shunt. The pathophysiologic course of cranial nerve palsies in patients with BIH is uncertain but in most cases probably represents a nonspecific pressure-related phenomenon, as was clearly demonstrated in this patient. The clinical association of BIH and facial diplegia has not, to our knowledge, been reported previously.

gamma-Glutamyl transpeptidase activity in benign and malignant human mammary epithelial lesions. Histochemical evaluation

gamma-Glutamyl transpeptidase (GGT) has been identified in many tissues. The enzyme is present in normal human serum and is accepted widely as an indicator of liver disease. gamma-Glutamyl transpeptidase has been characterized as a putative hepatocellular carcinoma marker in rats and humans and a similar role is suggested in carcinomas of other tissues, including breast, colon, and ovary. Using a histochemical technique to demonstrate GGT activity, we have defined characteristic staining patterns for 67 normal or benign, and 108 overtly malignant human breast lesions. Transitions between benign, atypical, and malignant tumors were observed as were differences between intraductal and infiltrating components of a tumor. Normal breast epithelium and nondysplastic proliferative lesions were characterized by concentrated apical and luminal staining with weak cytoplasmic activity. Malignant lesions exhibited diffuse cytoplasmic staining when staining was observed.

Nutritional care of patients with renal failure and diabetes

Planning effective strategies of nutritional care for individuals with diabetic renal failure requires consideration of nutritional, social and medical factors. Typically, the diet is limited in protein, sodium, fluid potassium, and phosphorus content. Poor diabetes control in renal failure has been associated with fluid overload; elevated serum triglyceride levels; hyperkalemic episodes; and impaired protein synthesis. A diabetic meal plan, modified to meet the required nutrient restrictions, is, therefore, routinely developed for each individual. Serial monitoring of nutritional indexes in each patient enables early detection of nutritional wasting and is useful in evaluating the effectiveness of corrective dietary measures.

Nutritional assessment and treatment of chronic renal failure

The experience with chronic renal failure in two institutions, a tertiary care referral hospital with a high prevalence of diabetes mellitus and a Veterans Administration Hospital, was utilized to formulate guidelines for the nutritional assessment and therapy of chronic renal failure. For optimal nutritional support of patients with renal failure, it is important to characterize objectively nutritional deficiencies. Thus, dietary history, anthropometric measurements (weight/height ratio, arm muscle circumference, and triceps skinfold), and serum protein measurements (total protein, albumin, and transferrin, in particular) provide valuable data concerning the nutritional status of the patient. The serum urea nitrogen to serum creatinine ratio and urea nitrogen appearance are useful for selecting optimal protein intake. The serum urea nitrogen/creatinine ratio must be interpreted with respect to the factors which influence it; i.e., the urea clearance and the urea nitrogen appearance. The goal of nutritional therapy is the preservation of body cell mass and function, fluid, electrolyte, and acid-base homeostasis, mineral balances, and with early use of dialysis, the avoidance of uremic toxicity. Nutritional therapy, especially in patients with superimposed illnesses and associated anorexia, may be enhanced by the use of formula feedings, tube feedings, and, if necessary, total parenteral nutrition.

Dirofilaria immitis: a zoonosis of clinical concern

Dirofilaria immitis, the dog heartworm, is responsible for an endemic zoonosis in the Southeastern United States. The nematode is capable of infesting the lungs of man, causing pulmonary nodules. The epidemiologic, morphologic, and clinical features of D immitis infestation are discussed.