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C Pappas

Publications and source records attributed to C Pappas.

At least 55 records · Page 3Linked to original sources
PubMed1993

Survival of Salmonella enteritidis during the manufacture of feta cheese made of pasteurized ewe's milk.

The behaviour of Salmonella enteritidis during the Feta cheese making process was investigated. Two lots of pasteurized whole ewe's milk were inoculated to contain 10(6) cfu/ml of S. enteritidis (strain AS1 and AS2) and were processed into Feta cheese following standard procedures. All samples were examined for S. enteritidis both quantitatively and qualitatively, while moisture, fat, water activity and pH were also measured. S. enteritidis was enumerated in duplicate samples by surface plating on SS agar. Selected salmonella-like colonies were identified biochemically and serologically. The enumerations have shown that S. enteritidis was initially entrapped in the curd. Then the growth of S. enteritidis gradually decreased and no Salmonellae were quantitatively enumerated after the 23rd day. However S. enteritidis was detected qualitatively in samples taken until the 38th day.

Animals↗
PubMed1992

Spironolactone pharmacokinetics and pharmacodynamics in patients with cirrhotic ascites.

The intent of this study was to identify pharmacokinetic and pharmacodynamic characteristics for spironolactone (SP) and its metabolites (canrenone, 6 beta-hydroxy-7 alpha-thiomethylspirolactone, 7 alpha-thiomethylspirolactone) in cirrhotics under steady state conditions. Nine cirrhotics with ascites participated in the study. Serial blood samples were drawn and urine was collected over a 26-hour period. Using a reverse-phase high performance liquid chromatography (HPLC) method, all samples were analyzed for SP, canrenone, 6 beta-hydroxy-7 alpha-thiomethylspirolactone, and 7 alpha-thiomethylspirolactone concentrations. Parent compound and metabolite urinary excretion rates as well as maximal concentrations and time at which these are observed were calculated. The apparent median terminal elimination rate constants (associated half-lives) were 0.0767 h-1 (9.04 hours) for SP, 0.0055 h-1 (126 hours) for 6 beta-hydroxy-7 alpha-thiomethylspirolactone, 0.029 h-1 (23.9 hours) for 7 alpha-thiomethylspirolactone and 0.012 h-1 (57.8 hours) for canrenone. SP metabolism is impaired in cirrhosis; terminal half-lives of SP and metabolites appear to be increased when compared with values reported in the literature for normals. When assuming a linear model, clearance-effect relationship estimates are best correlated with 7 alpha-thiomethylspirolactone and canrenone. Further research is required to identify specific pharmacokinetic and pharmacodynamic parameters for SP and its metabolites in this patient population.

Adult↗
PubMed1991

Cellular mechanisms of Cl- transport in outer medullary collecting duct.

The OMCDi secretes Cl- when perfused and bathed with symmetrical solutions. The route for this transepithelial Cl- movement appears to be the paracellular pathway, and the driving force is the lumen positive voltage generated by the process of electrogenic H+ secretion. Currently, there is no evidence to support the existence of a significant transcellular route for transepithelial Cl- movement. Although the primary function of the OMCDi is related to urine acidification, Cl- plays an important role in this process. The basolateral membrane of the OMCDi cell contains a band-3 related Cl-/HCO3- antiporter and a Cl- conductance. The Cl-/HCO3- antiporter serves as the primary route for the efflux of HCO3- generated during the process of H+ secretion. The Cl- conductance allows Cl- brought into the cell by the antiporter to recycle across this membrane. This conductance also serves to maintain cell charge balance. Accordingly, for each equivalent of H+ leaving the cell across the apical membrane, a Cl- equivalent exits the cell across the basolateral membrane. Based on whole-cell patch-clamp studies, this Cl- conductance is blocked by the Cl- channel blocker DPC. This conductance may also have a finite permeability to HCO3-, and thus could serve as a secondary route for cellular HCO3- efflux. Lastly, the conductance is activated by the beta-adrenergic agonist isoproterenol.

Animals↗
PubMed1990

Cerebral venous malformations.

Although cerebral venous malformations have been reported to cause epilepsy, progressive neurological deficits, and hemorrhage, their clinical significance remains controversial. In an attempt to clarify the natural history of the lesion and suggest an appropriate management strategy, the authors review their experience with 30 patients. In four patients with cerebellar venous angioma, an acute episode of ataxia was documented. The coexistence of a cavernous malformation was pathologically confirmed in the two patients who underwent surgery for bleeding presumed caused by the venous angioma. Infarction was shown in two patients and a tumor in two others. Follow-up periods ranged between 18 and 104 months, with only five patients symptomatic at the time of this report. Rebleeding had not occurred, nor had acute episodes of neurological dysfunction been documented. This clinical experience suggests that a venous malformation is frequently associated with other, more symptomatic conditions and is often erroneously identified as the source of the symptoms. Because the nature of the relationship between the venous malformation and the allied conditions remains ambiguous, it is recommended that patients harboring a "symptomatic" venous malformation undergo high-field magnetic resonance imaging to rule out underlying pathology, and that any such pathology be treated independently of the venous malformation.

Adolescent↗
PubMed1984

Congenital Plasmodium vivax malaria.

A case of congenitally acquired Plasmodium vivax malaria in an infant of a Vietnamese refugee is reported. The pathogenesis and treatment of congenital malaria are also discussed briefly. As many Southeast-Asian refugees are now emigrating to Australia, physicians should be aware of this rare form of malaria.

Adult↗
PubMed1981

Neural differentiation in the OTT-6050 mouse teratoma. Production of a tumor fraction restricted to stem cells and neural cells after centrifugal elutriation.

Dissociation and centrifugal elutriation procedures were applied to subcutaneous transplants of the OTT-6050 mouse teratoma line in order to enrich the neuroepithelial cells. One of the resultant cell fractions, designated IB-21, was then implanted beneath the renal capsule of syngeneic mice and rebanked every 3 to 6 weeks for a total of 58 passages over 5 years. Sequential passages resulted in a tumor restricted to stem cells and neural cells (neuroblasts and glial cells). The primitive neural cells lost the ability to form rosettes after the early transplants. Subcutaneous or intracerebral transplantation of these tumors evinced their capacity for further neuroepithelial differentiation, with the demonstration of astrocytes and occasional mature synapse-forming neurons. Conversion of the tumor to the ascitic form resulted in unorganized clusters of neoplastic cells in contrast to the highly structured embryoid bodies that are characteristic of the parent Ott-6050 line. The absence of non-neural cells in the IB-21 tumor fraction and its ability to demonstrate divergent neural differentiation suggest that a transplantable neural-determined cell population exists in the OTT-6050 mouse teratoma.

Animals↗
PubMed1981

CNS myelin and synapses in a spontaneous mouse ovarian teratoma showing neural differentiation. An immunohistochemical and electron microscopic study.

A morphologic (light-, electron microscopic, and immunohistochemical) study of a spontaneous ovarian teratoma, originating in the LT strain of mice and showing predominantly neural differentiation, has revealed an unusually large number of mature myelinated axons and synapses within areas of well-differentiated neuroepithelium. Most of the myelin was determined to be of CNS origin by its staining characteristics with the LFB-PAS stain, the absence of reticulin fibers by light microscopy and of basal laminae by electron microscopy in relation to the myelin sheaths, the presence of associated cells identified morphologically as oligodendrocytes, and by the strongly positive immunohistologic reaction obtained for myelin basic protein. Most synapses likewise appeared to be of the CNS type. This murine ovarian teratoma may therefore be a useful tool for the study of neoplastic myelinogenesis and synaptogenesis.

Animals↗
PubMed1979

Work capacity, contractile protein and quantitative electromyogram (EMG) changes following exercise or nandrolone decanoate treatment in experimentally induced muscle disuse atrophy in rats.

Anabolic steroid administration and planned exercise have been the two main methods applied to improve the function and morphology of atrophied muscle tissue. The effects of these two factors-specifically nandrolone decanoate administration and exercise by swimming on muscle weight, EMG activity, work capacity and on contractile protein content of rat gastrocnemius muscle, following experimentally induced atrophy by immobilization, were investigated. The results appear to support the conclusion that although both types of treatment obtain significant positive results exercise acts more effectively than the anabolic steroid in this respect.

Actomyosin↗
PubMedDate not supplied

ECG pattern recognition and classification using non-linear transformations and neural networks: a review.

The most widely used signal in clinical practice is the ECG. ECG conveys information regarding the electrical function of the heart, by altering the shape of its constituent waves, namely the P, QRS, and T waves. Thus, the required tasks of ECG processing are the reliable recognition of these waves, and the accurate measurement of clinically important parameters measured from the temporal distribution of the ECG constituent waves. In this paper, we shall review some current trends on ECG pattern recognition. In particular, we shall review non-linear transformations of the ECG, the use of principal component analysis (linear and non-linear), ways to map the transformed data into n-dimensional spaces, and the use of neural networks (NN) based techniques for ECG pattern recognition and classification. The problems we shall deal with are the QRS/PVC recognition and classification, the recognition of ischemic beats and episodes, and the detection of atrial fibrillation. Finally, a generalised approach to the classification problems in n-dimensional spaces will be presented using among others NN, radial basis function networks (RBFN) and non-linear principal component analysis (NLPCA) techniques. The performance measures of the sensitivity and specificity of these algorithms will also be presented using as training and testing data sets from the MIT-BIH and the European ST-T databases.

Algorithms↗
PubMedDate not supplied

Characteristics of dropouts in longitudinal research on aging: a study of Mexican Americans and Anglos.

The characteristics of dropouts in a four-year longitudinal study of Mexican Americans and Anglos aged 60 years and over are investigated. Dropouts are found to be significantly older, to be less healthy, to view themselves as older, and to be less active than persons remaining in the study. Subgroups of dropouts differ from each other; deceased persons and those who could not be located were found to be generally less advantaged than restudied persons, while refusers were found to be advantaged. Implications for longitudinal studies on aging are discussed.

Aged↗
PubMedDate not supplied

Repair of five distal radius fractures with an investigational cancellous bone cement: a preliminary report.

OBJECTIVE: The purpose of the study was to evaluate the feasibility of Norian SRS bone cement injected percutaneously into a distal radius following reduction in both preventing loss of reduction as well as safety. DESIGN: The study was a prospective clinical study with an established protocol. SETTING: The study was conducted at the Massachusetts General Hospital following approval of the institutions Investigational Review Board. All patients were required to read and approve an informed consent document. PATIENTS: While twenty patients' radiographs fulfilled the requirement of a dorsally displaced extraarticular fracture to have occurred within 72 hours of presentation, only five consented to participate fully and one voluntarily withdrew after a six-month follow-up. INTERVENTION: All fractures were reduced under regional or general anesthesia, and the Norian SRS was introduced via a catheter system into the metaphyseal defect of the fracture. A short arm cast was applied and remained in place for six weeks. MAIN OUTCOME MEASUREMENTS: Radiographic parameters of fracture reduction were measured prospectively by an independent radiologist throughout the 12 months of the study. Clinical parameters of hand and wrist function were measured prospectively by an independent occupational therapist. RESULTS: At 12-month follow-up, radial length was a mean 9.9 mm with an average loss of < 1 mm; radial angle maintained at a mean 25.4 degrees; volar angle was within normal range (0-21 degrees) in 4; and 1 patient had a dorsal angle of 7 degrees. Wrist motion improved 50 percent between 6 weeks and 3 months and improved further by 12 months when grip strength reached a mean of 88 percent of the contralateral side. Dorsal and volar extrusion of injected Norian SRS in 4 patients resorbed over time. There were no clinically significant adverse effects or complications. CONCLUSIONS: Norian SRS proved to be clinically safe and effective as a cancellous bone cement to maintain fracture reduction of unstable extraarticular distal radius fractures.

Bone Cements↗
PubMedDate not supplied

ECG processing techniques based on neural networks and bidirectional associative memories.

Two ECG processing techniques are described for the classification of QRSs, PVCs and normal and ischaemic beats. The techniques use neural network (NN) technology in two ways. The first technique, uses nonlinear ECG mapping preprocessing and subsequently for classification uses a shrinking algorithm based on NNs. This technique is applied to the QRS/PVC problem with good result. The second technique is based on the Bidirectional Associative Memory (BAM) NN and is used to distinguish normal from ischaemic beats. In this technique the ECG beat is treated as a digitized image which is then transformed into a bipolar vector suitable for input in the BAM. The results show that this method, if properly calibrated, can result in a fast and reliable ischaemic beat detection algorithm.

Algorithms↗