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101.
Prosthetic valve endocarditis: superiority of surgical valve replacement versus medical therapy only
VL Yu GD Fang TF Keys AA Harris LO Gentry PC Fuchs MM Wagener ES Wong 《Canadian Metallurgical Quarterly》1994,58(4):1073-1077
The objective of our study was to assess the long-term outcome of patients with prosthetic valve endocarditis. We used a multicenter, prospective, observational study design. Six university teaching hospitals with high volume cardiothoracic surgery participated. Seventy-four patients with prosthetic valve endocarditis as defined by explicit, objective criteria were selected for participation. All patients were followed up prospectively for 1 year. Thirty-one percent and 69% had development of endocarditis within 60 days of valve insertion ("early") and after 60 days ("late"), respectively. The most common causes were Staphylococcus epidermidis (40%), Staphylococcus aureus (20%), streptococcal species (18%), and aerobic gram-negative bacilli (11%). Physical signs of endocarditis (new or changing murmur, stigmata, emboli) were seen in 58%. At 6 months and 12 months, mortality was 46% and 47%, respectively. Surgical replacement of the infected valve led to significantly lower mortality (23%) as compared with medical therapy alone (56%), as assessed by both univariate and multivariate analyses (p < 0.05). Improved outcome was seen for the surgical group even when controlling for severity of illness at time of diagnosis. From these findings we conclude that accurate assessment of outcome in prosthetic valve endocarditis requires long-term follow-up of at least 6 months following diagnosis. Surgical therapy warrants greater scrutiny; evaluation in controlled clinical trials is appropriate. 相似文献
102.
Paired-pulse plasticity is typically used to study the mechanisms underlying synaptic transmission and modulation. An important question relates to whether, under physiological conditions in which various opposing synaptic properties are acting in parallel, the net effect is facilitatory or depressive, that is, whether cells further or closer to threshold. For example, does the net sum of paired-pulse facilitation (PPF) of excitatory postsynaptic potentials (EPSPs), paired-pulse depression (PPD) of inhibitory postsynaptic potentials (IPSPs), and the hyperpolarizing slow IPSP result in depression or facilitation? Here we examine how different time-dependent properties act in parallel and examine the contribution of gamma-aminobutyric acid-B (GABAB) receptors that mediate two opposing processes, the slow IPSP and PPD of the fast IPSP. Using intracellular recordings from rat CA3 hippocampal neurons and L-II/III auditory cortex neurons, we examined the postsynaptic responses to paired-pulse stimulation (with intervals between 50 and 400 ms) of the Schaffer collaterals and white matter, respectively. Changes in the amplitude, time-to-peak (TTP), and slope of each EPSP were analyzed before and after application of the GABAB antagonist CGP-55845. In both CA3 and L-II/III neurons the peak amplitude of the second EPSP was generally depressed (further from threshold) compared with the first at the longer intervals; however, these EPSPs were generally broader and exhibited a longer TTP that could result in facilitation by enhancing temporal summation. At the short intervals CA3 neurons exhibited facilitation of the peak EPSP amplitude in the absence and presence of CGP-55845. In contrast, on average L-II/III cells did not exhibit facilitation at any interval, in the absence or presence of CGP-55845. CGP-55845 generally "erased" short-term plasticity, equalizing the peak amplitude and TTP of the first and second EPSPs at longer intervals in the hippocampus and auditory cortex. These results show that it is necessary to consider all time-dependent properties to determine whether facilitation or depression will dominate under intact pharmacological conditions. Furthermore our results suggest that GABAB-dependent properties may be the major contributor to short-term plasticity on the time scale of a few hundred milliseconds and are consistent with the hypothesis that the balance of different time-dependent processes can modulate the state of networks in a complex manner and could contribute to the generation of temporally sensitive neural responses. 相似文献
103.
Current wisdom holds that health care is a business and "as such must abide by market principles." Most nurses are not well enough versed in economic theories to credibly critique health care delivery decisions based on economic theories. The relationship of market principles to health care realities is described in basic terms to encourage nurses to "optimize patient care and influence health care policy." Physicians, who control all access points to the health care system, have enjoyed a 40-year market dominance that is "rapidly being replaced by insurance companies and for-profit investors." Providers' decisions to treat or not to treat are strongly influenced by whether the patient is in a fee-for-service or capitated payment environment. 相似文献
104.
We recently reported that washed platelets (WP) activated with ADP and expressing surface-bound vWF aggregated in flow through small tubes or in a cylindrical couette device at physiological shear rates of G = 300 s(-1)-1000 s(-1) in the absence of exogenous ligands, with GPIb-vWF partially, and activated GPIIb-IIIa totally required for the aggregation. We have now extended these studies to aggregation of platelets "activated" with ristocetin or thrombin. Washed platelet suspensions with added soluble vWF and ristocetin (0.3-0.75 mg/ml), or activated with thrombin (0.01-0.5 U/ml) but no added ligand, were sheared in a coaxial cylinder device at uniform shear rate, G = 1000 s(-1). The collision capture efficiency (alphaG) with which small aggregates form (= experimental/calculated initial rates of aggregation) was correlated with vWF platelet binding assessed by flow cytometry. The vWF-GPIb interaction was exclusively able to support ristocetin-mediated shear aggregation of metabolically active platelets, with very few vWF monomer equivalents bound per platelet (representing < or = 10 molecules of 10 million Da) required to yield high capture efficiencies (alphaG = 0.38+/-.02; n = 11), suggesting rapid and stable bond formations between vWF and GPIb. However, platelet surface-expressed vWF, generated by addition of thrombin to washed platelets, was found to mediate platelet aggregation with alphaG = 0.08+/-.01 (n = 6), surprisingly comparable to that previously reported for WP and ADP activation. Blocking the GPIIb-Illa receptor decreased alphaG by 95+/-3% (n =3), while a monoclonal antibody to the vWF site on GPIb caused a 49+/-7% (n = 8) decrease in alphaG. The partial role for GPIb thus appears to reflect a facilitative function for increasing contact time between flowing platelets, and allowing engagement of the GPIIb-IIa receptor to yield stable attachment. 相似文献
105.
ES Wiener RJ Touloukian BM Rodgers JL Grosfeld EI Smith MM Ziegler AG Coran 《Canadian Metallurgical Quarterly》1996,31(8):1166-1169
The members of the Section on Surgery of the American Academy of Pediatrics were surveyed to determine the practice of North American pediatric surgeons in infants with inguinal hernia (IH). Case-scenario multiple-choice-design questionnaires regarding hernias and hydroceles were sent to all members of the Surgical Section, and responses were received from 292 (50%). In healthy full-term infant boys with asymptomatic reducible IH, 82% of responders perform repair electively, no matter what the age or weight. In full-term girls with a reducible ovary, 59% perform surgery at the next available time; if the ovary is nonreducible but asymptomatic, 44% operate emergently or urgently and 42% at the next elective slot. In former preemies, the pattern of repair is as follows. (1) For those recently discharged after 2 months in the neonatal intensive care unit (NICU) with reducible IH, 65% perform the repair when convenient. (2) A general anesthetic is used in 70%; 15% use spinal anesthesia, and 11% use caudal block with sedation. (3) If the repair is done in the hospital outpatient (same-day) unit, 36% wait until 50 weeks postconception (PC) and 33% wait until 60 weeks PC. (4) if the baby's weight is at least 1,000 g. 71% perform the repair before discharge. The pain control choice after childhood IH repair is Tylenol for 30%, local infiltration biquivacaine for 30%, caudal block for 22%, regional block for 11%, and Tylenol/codeine combined for 7%. In 6-week-old full-term infants with communicating hydroceles without definite "hernia," two thirds treat as an IH with elective repair as soon as possible. With respect to contralateral exploration in infants with unilateral IH, 65% perform it in males if they are < or = 2 years of age and 84% use it in females of up to 4 years of age. This approach is not influenced by presenting side, presence of hydrocele, or history of prematurity. Laparoscopic evaluation of the contralateral IH is performed by only 6% of responders, 40% of whom use the open ipsilateral sac for laparoscope introduction. 相似文献
106.
GG Stone MM Chengappa RD Oberst NH Gabbert S McVey KJ Hennessy M Muenzenberger J Staats 《Canadian Metallurgical Quarterly》1993,5(3):378-385
The polymerase chain reaction was employed to correlate Salmonella serovars isolated from fecal material of greyhounds suffering from gastroenteritis with those isolated from the diet fed to the greyhounds prior to onset of diarrhea. Kennels around the Abilene, Kansas, area were contacted and supplied with materials needed to collect a portion of the diet each day. With the onset of diarrhea, the kennels were instructed to ship the fecal material and diet from the previous 10 days to the laboratory for testing. Forty-one fecal samples and corresponding diets were screened for Salmonella, Clostridium perfringens, Campylobacter jejuni, Staphylococcus aureus, Staphylococcus intermedius, and pathogenic (piliated) Escherichia coli by direct culture using standard procedures. The fecal material was also screened for coronavirus and parvovirus using electron microscopy. Thirty-five "normal" fecal samples were screened for all of the above mentioned microorganisms as a control. In addition, the fecal material was screened for E. coli verotoxins I and II and clostridial enterotoxins. A total of 61 Salmonella isolates were recovered from the 41 samples of feces and diet submitted for testing; 31 were recovered from the feces and 30 from the diet. Four Salmonella isolates were recovered from the normal fecal samples. Results obtained by PCR, plasmid profiles, antigenic analysis, and antibiogram profiles indicated that 16 of the 31 isolates recovered from the fecal material were the same strain as that recovered from the diet. 相似文献
107.
HI McFarland AA Lobito MM Johnson JT Nyswaner JA Frank GR Palardy N Tresser CP Genain JP Mueller LA Matis MJ Lenardo 《Canadian Metallurgical Quarterly》1999,162(4):2384-2390
Definition of the immune process that causes demyelination in multiple sclerosis is essential to determine the feasibility of Ag-directed immunotherapy. Using the nonhuman primate, Callithrix jacchus jacchus (common marmoset), we show that immunization with myelin basic protein and proteolipid protein determinants results in clinical disease with significant demyelination. Demyelination was associated with spreading to myelin oligodendrocyte glycoprotein (MOG) determinants that generated anti-MOG serum Abs and Ig deposition in central nervous system white matter lesions. These data associate intermolecular "determinant spreading" with clinical autoimmune disease in primates and raise important issues for the pathogenesis and treatment of multiple sclerosis. 相似文献
108.
109.
Neurofibromatosis type 2 (NF2) is a dominantly inherited disorder characterized by the occurrence of bilateral acoustic neuromas (ANs and other central nervous system tumors. Magnetic resonance images and audiologic data on 22 patients with NF2 who underwent multiple studies at the National Institutes of Health between 1983 and 1993 were reviewed to determine the growth characteristics of ANs in these patients. The average growth rate of ANs in NF2 patients was 0.30 cm3 per year and was significantly higher in older patients (0.75 cm3 per year) than in younger ones (0.12 cm3 per year). Larger ANs were more commonly found in patients with concomitant spinal tumors or meningiomas. NF2 patients with spinal tumors but not meningiomas demonstrated faster growth rates than patients without additional tumor burden. The data from this study suggest that older patients or patients with associated spinal tumors have faster growing ANs and therefore should be followed closely and treated aggressively. 相似文献
110.
DM Parry MM MacCollin MI Kaiser-Kupfer K Pulaski HS Nicholson M Bolesta R Eldridge JF Gusella 《Canadian Metallurgical Quarterly》1996,59(3):529-539
Neurofibromatosis 2 (NF2) features bilateral vestibular schwannomas, other benign neural tumors, and cataracts. Patients in some families develop many tumors at an early age and have rapid clinical progression, whereas in other families, patients may not have symptoms until much later and vestibular schwannomas may be the only tumors. The NF2 gene has been cloned from chromosome 22q; most identified germ-line mutations result in a truncated protein and severe NF2. To look for additional mutations and clinical correlations, we used SSCP analysis to screen DNA from 32 unrelated patients. We identified 20 different mutations in 21 patients (66%): 10 nonsense mutations, 2 frameshifts, 7 splice-site mutations, and 1 large in-frame deletion. Clinical information on 47 patients from the 21 families included ages at onset and at diagnosis, numbers of meningiomas, spinal and skin tumors, and presence of cataracts and retinal abnormalities. We compared clinical findings in patients with nonsense or frameshift mutations to those with splice-site mutations. When each patient was considered as an independent random event, the two groups differed (P < or = .05) for nearly every variable. Patients with nonsense or frameshift mutations were younger at onset and at diagnosis and had a higher frequency and mean number of tumors, supporting the correlation between nonsense and frameshift mutations and severe NF2. When each family was considered as an independent random event, statistically significant differences between the two groups were observed only for mean ages at onset and at diagnosis. A larger data set is needed to resolve these discrepancies. We observed retinal hamartomas and/or epiretinal membranes in nine patients from five families with four different nonsense mutations. This finding, which may represent a new genotype-phenotype correlation, merits further study. 相似文献