A method for repair of aortic dissection originating in the transverse arch using two sutureless intraluminal prostheses

We present a method for repair of ascending aortic dissections that originate in the transverse aortic arch. The technique utilizes two sutureless intraluminal prostheses, which are joined together and inserted during hypothermic circulatory arrest. A diamond-shaped opening between the two grafts is anastomosed about the orifices of the brachiocephalic arteries. This method affords the advantage of excluding the intimal tear, thereby preventing further propagation of the dissection. Additionally, the method offers the time-saving advantage of the sutureless prosthetic rings for the proximal and distal anastomoses.     

Immunogenic and Antigenic Epitopes of Immunoglobulins Binding of Human Monoclonal Anti-D Antibodies to FcRI on the Monocyte-Like U937 Cell Line

Seventeen human monoclonal IgG1- or IgG3 anti-D-secreting clones have been examined for their ability to sensitise O+ red cells for Fc-receptor-mediated rosette formation with U937 cells. IgG3 but not IgG1 anti-D antibodies were able to mediate stable rosette formation with unstimulated U937 cells via interaction with the FcRI receptor. Decreasing FcRI density by incubating U937 cells with di-butyryl cAMP almost completely abolished rosette formation, whilst increasing FcRI density by incubating U937 cells with interferon-gamma increased the percentage of cells forming rosettes with IgG3- and IgG1-sensitised red cells. These data suggest that rosette formation between IgG anti-D-sensitised red cells and FcRI-expressing cells is dependent upon the density of IgG3 on the red cell surface, the density of FcRI on the effector cell, multiple FcRI/IgG interactions are required for stable rosette formation and that more FcRI/IgG1 than FcRI/IgG3 interactions are required.     

A comparison of the insulinotropic and the insulin-inhibitory actions of gut peptides on newborn and adult rat islet cells

The objective of this study was to examine the release of insulin from cultured islet cells, taken from the pancreas of newborn and adult rats, in response to gastric inhibitory polypeptide (GIP), cholecystokinin-8 (CCK-8), calcitonin gene-related peptide (CGRP), and pancreastatin. GIP (10(-9)-10(-7) M) potentiated glucose-stimulated release of insulin in a dose-dependent fashion from both newborn and adult islet cells. CCK-8 (greater than 10(-8) M) also increased glucose-stimulated release of insulin from newborn islet cells, however its effect was not significant and not as strong as that observed with adult islet cells. Culture of newborn islet cells for 3 weeks with media containing high concentrations of glucose (16.7 mM) enhanced insulin release in response to CCK-8. CGRP did not affect the release of insulin from newborn islet cells, whereas at 10(-10) M, it reduced the release of insulin from adult islet cells by 66 +/- 4%. Pancreastatin (10(-9)-10(-8) M) did not affect the release of insulin from newborn islet cells when cells were incubated with 4.2 mM glucose, whereas it stimulated the release of insulin from adult islet cells in a dose-dependent fashion. When incubated with 16.7 mM glucose, pancreastatin inhibited the release of insulin from both newborn and adult islet cells. These results indicate that newborn islet cells experience developmental changes which render them responsive to enteric peptides.     

Short-term synaptic plasticity, simulation of nerve terminal dynamics, and the effects of protein kinase C activation in rat hippocampus

Phorbol esters are hypothesised to produce a protein kinase C (PKC)-dependent increase in the probability of transmitter release via two mechanisms: facilitation of vesicle fusion or increases in synaptic vesicle number and replenishment. We used a combination of electrophysiology and computer simulation to distinguish these possibilities. We constructed a stochastic model of the presynaptic contacts between a pair of hippocampal pyramidal cells that used biologically realistic processes and was constrained by electrophysiological data. The model reproduced faithfully several forms of short-term synaptic plasticity, including short-term synaptic depression (STD), and allowed us to manipulate several experimentally inaccessible processes. Simulation of an increase in the size of the readily releasable vesicle pool and the time of vesicle replenishment decreased STD, whereas simulation of a facilitation of vesicle fusion downstream of Ca²⁺ influx enhanced STD. Because activation of protein kinase C with phorbol ester enhanced STD of EPSCs in rat hippocampal slice cultures, we conclude that an increase in the sensitivity of the release process for Ca²⁺ underlies the potentiation of neurotransmitter release by PKC.     

Organizational and market factors associated with Medicare dependence in inpatient rehabilitation hospitals.

Rehabilitation hospitals in the USA have been excluded from the Medicare Prospective Payment System (PPS) system since 1982, and have received cost-based reimbursement. However, the 1997 Balanced Budget Act mandated a PPS for inpatient rehabilitation, to be implemented by the end of 2002. This study assesses rehabilitation hospitals' dependency on Medicare. Findings show that not-for-profit hospitals, facilities with fewer services, facilities with lower staffing levels, and hospitals with lower operating expenses and profits, have a higher proportion of their inpatient revenue coming from Medicare. These facilities may be vulnerable to the new PPS payment system.     

一项对原发进行性多发性硬化症患者认知功能的纵向研究

有关多发性硬化症患者认知功能的纵向研究很少，并且上述研究的结果也不明确，迄今尚无专门关于原发进行性多发性硬化症（PPMS）病例系列的连续神经心理学资料。横断面分析揭示，PPMS患者的认知功能与磁共振成像（MRI）参数之间显著相关。本研究持续2年时间对来源于5个欧洲中心的99例PPMS患者的认知功能和MRI改变进行探讨。采用简易可重复问卷（一种推理能力测试）和抑郁量表每隔12个月对患者进行评估，同时在每个时间点对T1低信号负荷、T2损伤负荷和部分脑体积的MRI参数进行测算。基线和2年时患者的平均认知功能得分间无显著差异。然而，1／3患者的单独测试得分表现出绝对的认知功能下降。研究结果提示，纳入研究时的初始认知状态是2年后认知能力的一个可靠预测指标。认知功能改变和MRI改变间仅有少数几项指标显著相关，值得一提的是T1低信号负荷与2项注意力测试任务相关（r=-0．266，P=0．017；r=-0．303，P=0．012），可能是由多种因素造成认知功能和MRI参数间的这种弱相关。     

A prospective investigation of pulmonary embolism in women and men.

OBJECTIVE. The aim of this study was to compare, in women and men suspected of pulmonary embolism, the frequency, risk factors, diagnosis, and presentation of pulmonary embolism as well as the accuracy of the ventilation/perfusion scan (V/Q scan) as a diagnostic tool. DESIGN. Data were collected during a prospective study (the Prospective Investigation of Pulmonary Embolism Diagnosis) to establish the accuracy of the V/Q scan compared with pulmonary angiograms. SETTING. Six tertiary medical centers in Massachusetts, Michigan, Connecticut, Pennsylvania, and North Carolina. PARTICIPANTS. Patients suspected of pulmonary embolism for whom a request was made for a V/Q scan or pulmonary angiogram (496 women and 406 men). RESULTS. Women 50 years old and under had a decreased frequency of pulmonary embolism compared with men of that age (16% vs 32%), but there was no difference in patients over 50 years old (Breslow-Day test, P less than .01). Risk factors for pulmonary embolism, the usefulness of the V/Q scan, and 1-year mortality were not different for women and men. Estrogen use in women was not associated with an increased frequency of pulmonary embolism, except in women using oral contraceptives who had undergone surgery within 3 months; four of five (80%) had emboli compared with four of 28 (14%) age-matched surgical patients not using estrogens (P less than .01). CONCLUSION. Women 50 years old and under (even young women using oral contraceptives) who were suspected of having pulmonary emboli and were enrolled in the Prospective Investigation of Pulmonary Embolism Diagnosis study had a smaller frequency of pulmonary embolism than men of that age, The risk factors for pulmonary embolism were the same for women and men, except that women using oral contraceptives had an increased risk of pulmonary embolism following surgery. Although the V/Q scan was a useful tool in the preliminary evaluation for pulmonary embolism in these women, a pulmonary angiogram was often needed for accurate diagnosis.     

Inward rectification in response to FMRFamide in Aplysia neuron L2: summation with transient K current

The response of Aplysia abdominal ganglion neuron L2 to the molluscan neuroactive peptide Phe-Met-Arg-Phe-NH2 (FMRFamide) was studied in voltage-clamp experiments. In all of the experiments, focal application of the peptide to the soma activated an inward rectifier current and reduced the apparent amplitude of the transient K current, IA. In a few cells, Na and K currents were activated in addition to these effects. Voltage-jump experiments were performed to study the ionic dependence, kinetics, and voltage dependence of the inward rectifier. Inward rectification increased exponentially during hyperpolarizing pulses and recovered exponentially on return to the resting potential. The reversal potential was variable, but was near -40 mV at the beginning of experiments. Inward rectification was insensitive to changes in external Na, Ca, or K concentration, but lowering the external Cl concentration had complicated effects on current amplitude. When KCl microelectrodes were used, perfusion with low-Cl external saline increased the amplitude of the peptide-dependent inward rectifier and shifted its reversal potential to a more positive voltage. With KAc microelectrodes, perfusion with low-Cl saline reduced the amplitude of the current. Inward rectification increased when a KAc microelectrode was withdrawn and replaced with a low-resistance KCl electrode, even when there was no measurable change in reversal potential. These results suggest that the FMRFamide-dependent inward rectifier is a Cl current that, like the current described by Chesnoy-Marchais (1982, 1983), is modulated by intracellular Cl. FMRFamide reduced the apparent amplitude of IA without affecting the voltage dependence of IA activation or inactivation.(ABSTRACT TRUNCATED AT 250 WORDS)