Influence of vertebral fat content on quantitative CT density

Single- and dual-energy (85 and 130 kVp) computed tomographic (CT) measurements of bone density were made in 74 lumbar (L-3) vertebral specimens. Single-energy CT densities at 130 kVp consistently underestimated actual ash density by about 25 mg/cm3 in men and 40 mg/cm3 in women. CT densities overestimated age changes by 73% in women and 26% in men. These errors of the single-energy CT approach seemed due to increased marrow fat caused by age. At 130 kVp, there was a large decrease in apparent bone density (13 mg/cm3) for each increase of 100 mg/cm3 in fat content, but the decrease was lower at 85 kVp (11 mg/cm3), suggesting the use of lower energies for quantitative CT. In the vertebrae from the younger subjects (up to age 69), the relative error was 20%-31%, but in the oldest group it amounted to 31%-45%. The 95% confidence interval for an individual determination was +/- 38 mg/cm3. Dual-energy CT greatly reduced the above errors. Ash density was predicted with only a small accuracy error (7 mg/cm3) using a postprocessing dual-energy calculation, but the prediction error was 19 mg/cm3 for determinations at 130 kVp. The large uncertainty in the fat content of marrow (+/- 110 mg/cm3) and the variability in distribution of fat make dual-energy approaches necessary for accurate determinations of vertebral mineral density.     

Hepatic cavernous hemangioma: magnetic resonance imaging. Work in progress

Using a 0.35-T superconducting magnet and spin echo imaging, we prospectively evaluated 11 patients who had proved hepatic cavernous hemangioma. Magnetic resonance (MR) identified more lesions than either contrast-enhanced CT, or ultrasonography. The MR appearance was consistent; hemangiomas were homogeneous and generally isointense at short TR and TE intervals but were hyperintense at long TR intervals and greatly hyperintense at long TR and long TE intervals. However, the MR appearance of hemangioma was not specific; 2/14 other focal hepatic masses had similar features. The calculated relaxation times (T1, T2) were not useful in lesion characterization, although the intensity ratio of hemangioma to normal liver at the TR = 2.0 sec TE = 56 msec pulse sequence was useful in diagnosis since hemangiomas always had a ratio greater than 1.4.     

Attenuation of serotonin–induced contractures in skeletal muscle from malignant hyperthermia–susceptible patients with dantrolene

Background : Porcine malignant hyperthermia (MH) can be triggered by administration of certain serotonin₂ receptor agonists. Pretreatment with dantrolene completely abolished serotonininduced MH. The purpose of this study was to investigate the effects of the serotonin₂ receptor agonist l–(2,5–dimethoxy–4–iodophenyl)–2–aminopropane (DOI) in skeletal muscle specimens from MH–susceptible (MHS) and MH–nonsusceptible (MHN) patients following pretreatment with dantrolene.
Results : Administration of DOI 0.02 mM induced contractures in muscle specimens from MHS and MHN patients. Contracture development started significantly earlier in MHS than in MHN specimens. In MHS muscle the maximum contracture was significantly greater than in MHN. Pretreatment with dantrolene significantly delayed the start of contracture development in MHS muscles, whereas in MHN muscles no contractures were observed after dantrolene. The contracture maximum was significantly reduced in MHS.
Conclusion : The acceleration of DOI–induced contracture development in skeletal muscle specimens from MHS patients indicates that an altered serotonin system might be involved in human MH. Dantrolene effectively delayed serotonin–induced contractures. Further investigations are needed to determine whether serotonin₂ receptors of skeletal muscle from MHS subjects are altered in function or structure, or whether this response is a secondary phenomenon.
Method : We used muscle specimens surplus to diagnostic requirements from 12 MHS and 13 MHN patients in this study. In the first experiment, DOI 0.02 mM was added to the organ bath. In the second experiment, muscle specimens were preincubated with dantrolene 0.5 μM or 1.0 nM, respectively, for 10 min before DOI 0.02 mM was administered.     

Microcatheter CSA in a young woman with Fontan repair undergoing elective sterilization

We present the case of a 28–yr–old woman with Fontan anastomosis undergoing elective sterilization. Because of concerns about laparoscopic surgery with capnoperitoneum and positivepressure ventilation, a mini–laparotomy was performed in microcatheter spinal anaesthesia. Tiration of small doses of plain bupivacaine 0.5% supplemented with 5 μg sufentanil provided high cardiocirculatory and respiratory perioperative stability in this patient.     

色素减少性蕈样肉芽肿的微小残留病变

作者报道1例I期色素减少性蕈样肉芽肿，患者为一13岁男孩，尽管临床上病情得到完全缓解，但T细胞受体γ多聚酶联反应发现仍有微小残留病变。通过对缓解后皮损的T细胞受体γ多聚酶联反应产物的进一步克隆和测序，发现原发性T细胞克隆仍存在，但数量有所下降。随访3年半，无任何新出皮损。蕈样肉芽肿残留的恶性T细胞克隆的临床意义还有待阐明。     

Increased basal and induced tyrosine phosphorylation of the insulin- like growth factor I receptor beta subunit in circulating mononuclear cells of patients with polycythemia vera

We have previously shown that circulating progenitor cells in patients with polycythemia vera (PV) are hypersensitive to insulin-like growth factor I (IGF-I) with respect to erythroid burst formation in serum- free medium, and that this effect occurs through the IGF-I receptor. To investigate the molecular basis of this IGF-I hypersensitivity phenomenon, we examined tyrosine phosphorylation of the IGF-I receptor beta subunit in peripheral blood mononuclear cells (PBMNC) from eight PV patients and six normals. Cells were exposed to IGF-I at concentrations of 10(-8) and 10(-10) mol/L for 0, 1, 3, and 10 minutes, and then lysed. The IGF-I receptor beta subunit was immunoprecipitated, and the protein was resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotted with antiphosphotyrosine antibody (4G10). We found that, in the absence of exogenous IGF-I, there was a basal level of tyrosine phosphorylation of the IGF-I receptor beta subunit, and it was substantially greater in PV than in normal. At 10(-10) mol/L IGF-I in normals, no evidence of increased tyrosine phosphorylation was detected; however in PV, a pronounced increase in tyrosine phosphorylation was observed at both 10(-10) and 10(-8) mol/L IGF-I, and it occurred earlier and attained a higher level than in normal. In contrast, in PBMNC from three patients with erythrocytosis, no significant increase above normal was seen in either basal or induced tyrosine phosphorylation of the IGF-I receptor beta subunit. Thus, our findings show two distinctive features of the PV phenotype in PBMNC: (1) an increased basal tyrosine phosphorylation of the IGF-I receptor beta subunit, and (2) a hypersensitive and hyperresponsive receptor with respect to tyrosine phosphorylation. These features may influence the ability of the receptor to transmit a proliferative signal; thus, they may play a role in the pathogenesis of PV.     

A longitudinal study of the emergence of phonemes in children with down syndrome

Articulation norms are typically used to measure sound acquisition and mastery in children with Down syndrome. The present longitudinal study examines the clinical records of 60 children with Down syndrome to evaluate phoneme acquisition and emergence. Results document the order of emergence of sounds in children with Down syndrome. Factors affecting emergence of sounds (e.g. oral motor skills) and difficulties in using a mastery model to evaluate speech sound acquisition in children with Down syndrome are explored. Clinical as well as research implications of the data are presented.     

The substitutability of outpatient primary care in rural community health centers for inpatient hospital care.

To determine whether outpatient medical care obtained at federally funded rural community health centers (CHCs) in Maine acts primarily as a substitute or as a complement to inpatient care, a study of 36 communities served by CHCs was conducted. The hospital use of CHC users (age- and sex-adjusted admissions, days, and length of stay) was compared with that of nonusers from the same communities in 1980. Statistically lower rates of hospital admissions and days were observed for all CHC patients and for selected groups based on their age, sex, and insurance status (specifically Medicaid or Medicare). Hospital use of CHC community populations was then compared with that of 24 comparison communities without access to CHCs, using multiple linear regression in a pre/post design. The model tested, which included rates of health center use, insurance penetration, poverty, and hospital availability, among other factors, did not detect any differences in hospital use between CHC community and comparison populations. These results and additional data presented on selected hospital diagnoses and insurance coverage suggest that treatment, and hospitalization incentives, of CHC providers may reduce hospitalization. Clinic providers lack the economic, professional, and institutional incentives to hospitalize. Additional study to determine the actual substitutability effect is indicated.