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Biomedical subjects

R Cohen

Publications and source records attributed to R Cohen.

At least 271 records · Page 15Linked to original sources
PubMed1994

Bacterial pseudomycosis: a rare cause of haemoptysis.

Pulmonary bacterial pseudomycosis, also referred to as botryomycosis, is a very rare, indolent illness that has been described mostly in patients with immunological problems. The histological appearance is similar to that of actinomycosis; however, various Gram-positive and Gram-negative bacteria have been implicated in the pathogenesis. We illustrate a rapidly progressive case of pulmonary bacterial pseudomycosis in a normal host whose presenting complaint was haemoptysis.

Aged↗
PubMed1994

Pseudotumoral lymphocytic hypophysitis successfully treated by corticosteroid alone: first case report.

We report the first case of pseudotumoral lymphocytic hypophysitis successfully treated by corticosteroids without surgery. A 27-year-old woman had been monitored for chronic headache 13 months after giving birth, associated with amenorrhea and galactorrhea. Cranial magnetic resonance imaging revealed a markedly enlarged pituitary gland with a suprasellar extension; the only biochemical abnormality was a mild hyperprolactinemia. Because of a putative diagnosis of prolactinoma, bromocriptine was prescribed at a dose of 5 mg daily, soon followed by the transitory appearance of menstruation. Two years later, panhypopituitarism was present and was revealed by acute adrenal insufficiency. Magnetic resonance imaging revealed that the pituitary mass was the same as previously described, but hormonal investigation showed evidence of complete hypopituitarism and no hyperprolactinemia. Nuclear antibodies were negative as well as other autoantibodies. Human leukocyte antigen serological Class II typing was DR3/DR4. Lymphocytic hypophysitis was then suspected; in the absence of visual complication and because this patient refused surgery, corticosteroids were attempted at a daily dose of 60 mg of prednisone for 3 months, progressively decreased for the next 6 months. Under this treatment, a gradual recovery of all pituitary hormones was observed and magnetic resonance imaging showed a reduction of two-thirds in pituitary mass. Five months after the end of corticoid treatment, our patient relapsed with panhypopituitarism and an increase of pituitary volume. She underwent steroid treatment, and a biopsy was performed and confirmed the diagnosis of autoimmune hypophysitis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Flow cytometric analysis and cytokeratin typing of human lung tumors. A preliminary study.

In the current study a comparative analysis of keratin typing and DNA content was carried out in human lung tumors from transthoracic fine needle aspiration biopsies (TFNAB) (18 patients) or from surgically resected tumor tissues (14 patients). According to the cytologic and histologic features, 2 of the 32 tumors were diagnosed as benign tumors, 11 as squamous cell carcinomas, 12 as adenocarcinomas, and 7 as undifferentiated large cell carcinomas. Two cases in the adenocarcinoma and one in the undifferentiated large cell carcinoma groups were pulmonary metastasis or second primary tumors. Malignant cells of tumors which reacted positively with KK8.60 anticytokeratin polypeptides No. 10 and 11 (and hence contain keratinizing cells) displayed diploid DNA content in a flow cytometric assay regardless of their cytologic or histologic appearance. In contrast, all tumors which lacked such positive cells (most of which were defined as adenocarcinomas and undifferentiated tumors) were hyperdiploid. The close correlation between high DNA content and both malignancy and the absence of advanced squamous differentiation (keratinization) suggests that such combined analysis may provide new tools for the cytologic diagnosis and prognosis of lung cancers.

Adenocarcinoma↗
PubMed1994

[Treatment of Streptococcus pneumoiae meningitis in infants].

Due to a worldwide increasing number of cephalosporin resistant Streptococcus (S) pneumoniae strains, it appears necessary to modify the current treatment of pneumococcal meningitis. The authors recommend an initial antimicrobial regimen associating cefotaxime or ceftriaxone to vancomycin in any case of bacterial meningitis in which S pneumoniae appears to be involved (Gram positive cocci on direct examination of the CSF and/or presence of soluble bacterial antigen). There is also a need for a reappraisal of the duration of the treatment which, in any case, should not be shorter than 10 days. In the case of meningitis due to a penicillin resistant S pneumoniae, lumbar puncture must be repeated until sterilisation of the CSF.

Cefotaxime↗
PubMed1994

Treatment failure in otitis media: an analysis.

An epidemiological study was conducted in order to monitor the involvement of penicillin-resistant pneumococci (PRP) in treatment failure in acute otitis media (AOM), in an area of France where resistance to antibiotics is high. A total of 293 children presenting to 12 ear, nose and throat (ENT) specialists were included in the study. The mean age of the patients was 15.3 months and most of the children (58.7%) were attending day care centres. Bacteriological sampling demonstrated that in 146 cases (49.8%), no pathogen was present at the time of treatment failure. In the remaining patients Streptococcus pneumoniae was the most frequently recovered pathogen, being isolated from 81/147 (55.1%) of bacteriologically documented cases. Serotype 23F was the predominant strain, representing 53% of all S. pneumoniae isolates recovered. Resistance or reduced susceptibility to the prescribed antibiotic was seen in 70/81 (86.4%) of the S. pneumoniae isolates. In 32 out of 49 children administered a beta-lactam antibiotic, treatment failure involved PRP. Amoxycillin seemed to be the most active oral beta-lactam against these pathogens. The multiresistance of S. pneumoniae poses a serious therapeutic problem and should make myringotomy and bacteriological sampling obligatory in cases of antibiotic treatment failure.

Acute Disease↗
PubMed1994

[Septicemia due to Streptococcus milleri with pulmonary complications].

BACKGROUND: Streptococcus milleri can occasionally cause serious septicemia, that is often complicated by abscesses, particularly pulmonary. CASE REPORT: A 12.5 year-old boy was admitted because he had suffered from fever for 6 days. He also had headache, diffuse abdominal pain, chills and a cough. Laboratory investigations showed leukocytes: 9,300/mm3 (PMN: 6,700/mm3; lymphocytes: 1,400/mm3; monocytes: 1,200/mm3); hemoglobin: 12.5 g/dl; platelets: 106,000/mm3; sedimentation rate: 120 mm at 1 hour; blood fibrinogen: 5.6 g/l and C-reactive protein: 193 mg/l. His chest X-rays was normal. Four blood cultures showed Streptococcus milleri. The patient was given amoxicillin (150 mg/kg/d) plus gentamicin (3 mg/kg/d). Two foci of dental infection were found and treated by tooth extraction. Blood cultures remained positive 2, 3 and 6 days after onset of treatment and a second chest X-rays and CT scan showed several bilateral pulmonary abscesses. Cardiac ultrasonographs showed no valvular vegetations. The patient was then given ceftriaxone (100 mg/kg/d) plus rifampicin (20 mg/kg/d) and netilmicin (6 mg/kg/d). Blood culture was negative two days later, but the fever persisted and ceftriaxone was then successfully replaced by vancomycin (40 mg/kg/d) for three weeks. CONCLUSION: There are several reasons for the apparent resistance to treatment of this potentially severe infection; they are discussed by the authors.

Bacteremia↗
PubMed1994

[Physiopathological approach and antenatal diagnosis of diabetes mellitus insulin resistant: apropos of a case with leprechaunism].

BACKGROUND: Leprechaunism is characterized by severe intrauterine growth retardation, elfin-like face, relatively large hands, feet and genitalia and abnormal skin with hypertrichosis, acanthosis nigricans and low subcutaneous fat. The insulin receptors have multiple defects. CASE REPORT: A boy was born after cesarean section at the 35th week of gestation because of intrauterine growth retardation: weight: 930 g; height: 36 cm; head circumference: 27 cm. He had trigonocephaly, coarse features and hyperkeratosis. Ultrasonography confirmed the presence of a ventricular septal defect detected during pregnancy. Hyperglucosemia (3 g/l) was associated with insulinemia above 350 mU/l; his C-peptide concentration was above 20 ng/ml. The patient was given intravenous insulin, up to 2,500 U/kg/d. He died at the age of 95 days, weighing 1500 g, with persistent hyperglucosemia and cholestasis. Postmortem examination showed adrenal and thymus hypoplasia and hyperplasia of pancreatic islet cells. Molecular biology studies showed that this patient was heterozygotic for two mutations, one in exon 20 inherited from his father, the other in exon 18 inherited from his mother; both mutations are associated with tyrosine-kinase activity of the insulin receptor. These results will be used for antenatal diagnosis in any future pregnancy. CONCLUSION: Molecular biology can indicate specific defects in the insulin receptor. It may also allow antenatal diagnosis in some families.

Abnormalities, Multiple↗
PubMed1993

Transmembrane ammonium sulfate gradients in liposomes produce efficient and stable entrapment of amphipathic weak bases.

Gradients of ammonium sulfate in liposomes [(NH4)2SO4]lip. > [(NH4)2SO4]med. were used to obtain 'active' loading of amphipathic weak bases into the aqueous compartment of liposomes. The loading is a result of the base exchange with the ammonium ions. This approach was applied to encapsulate anthracyclines and acridine orange inside the liposomes at very high efficiency (> 90%). Doxorubicin was accumulated in the aqueous phase of the liposomes where it reached a level as high as 100-fold the doxorubicin concentration in the remote loading medium. Most of the intraliposomal doxorubicin was present in an aggregated state. The active entrapment and loading stability were dependent on liposome lipid composition, lipid quality, medium composition and temperature, as well as on the pKa and hydrophobicity of the base. The ammonium sulfate gradient approach differs from most other chemical approaches used for remote loading of liposomes, since it neither requires preparation of the liposomes in acidic pH, nor to alkalinize the extraliposomal aqueous phase. The stability of the ammonium ion gradient is related to the low permeability of its counterion, the sulfate, which also stabilizes anthracycline accumulation for prolonged storage periods (> 6 months) due to the aggregation and gelation of anthracycline sulfate salt.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1993

The ethics objective structured clinical examination.

OBJECTIVE: To develop objective structured clinical examination (OSCE) stations to assess the ability of physicians to address selected clinical-ethical situations, and to evaluate inter-rater agreement in these stations. DESIGN: Two ten-minute OSCE stations were developed using video-taped encounters between attending physicians and standardized patients. One scenario involved a daughter requesting a do-not-resuscitate (DNR) order for her competent mother without the mother's knowledge; the other involved a competent elderly woman requesting not to be re-intubated if her congestive heart failure worsened. The scenarios were evaluated using foreign medical graduates taking an OSCE. Each candidate was scored on his or her interaction with a standardized patient in the two OSCE stations by two independent observers. PARTICIPANTS: Eight attending physicians from the Division of General Internal Medicine at the Toronto Hospital were used to develop the OSCE stations, and 69 foreign medical graduates taking the University of Toronto Pre-Internship Program OSCE were used to evaluate the stations. RESULTS: The inter-rater reliability coefficients for the DNR and intubation scenarios were 0.79 (95% CI 0.69-0.87) and 0.75 (95% CI 0.62-0.84), respectively. For the DNR station, the scores of the two examiners, on a scale of 0 to 10, agreed exactly for 34 candidates (50%), within one mark for 59 candidates (87%), and within two marks for 65 candidates (96%). For the intubation station, the scores of the two examiners agreed exactly for 27 candidates (40%), within one mark for 56 candidates (84%), and within two marks for 63 candidates (94%). CONCLUSIONS: The authors produced ethics OSCE stations with face and content validity and satisfactory inter-rater agreement. Ethics OSCE stations may be suitable for evaluating the ability of medical students and residents to address selected clinical-ethical situations.

Analysis of Variance↗
PubMed1993

In vitro tests to predict in vivo performance of liposomal dosage forms.

Design of liposome-based formulations for clinical use can be assisted by employing in vitro assays to predict pharmacokinetics and bioavailability of the drug before employing costly and time-consuming in vivo studies. For such formulations of the anti-cancer drug doxorubicin (DXR) we developed two assays. (A) An assay which determines the dilution-induced DXR release in buffers and plasma. This assay was employed to evaluate two liposomal DXR formulations: (i) membrane-associated liposomal doxorubicin (L-DXR), and (ii) sterically-stabilized liposomes which encapsulate DXR in the aqueous phase of the liposomes (S-DXR). The agreement between the dilution-induced release assay in vitro and the pharmacokinetics of DXR administrated either as L-DXR or as S-DXR in humans suggests that the dilution release assay can be used as a predictor for the pharmacokinetic performance of liposomal formulations. (B) An assay which determines intracellular drug release induced by liposome degradation in the presence of mouse liver lysosome lysate. This assay was used to assess bioavailability of DXR when delivered via L-DXR, which are taken up by the reticuloendothelial system (RES). (C) An assay which complements conventional chromatographic analyses (HPLC or TLC) of the drug, in which a DXR adduct or aggregate was determined by using Sephadex LH-20 gel exclusion chromatography.

Animals↗
PubMed1993

"Probing" the nature of the CNV.

A widespread depolarization in the dendritic trees of cortical pyramidal neurons generates surface-negative potentials. In turn, such potentials may indicate facilitatory processes, while positive-going waves may result from a lowering in cortical excitability. Accordingly, we may expect the processing of "probe" stimuli presented during surface-positive waves, i.e., during phases of lesser excitability, to be inhibited and probes presented during surface-negative waves to be facilitated. This hypothesis was tested by presenting acoustic probe stimuli at various points in time during a forewarned reaction time task. The warning stimulus (WS) elicited a late positive complex followed by a negative slow potential shift (CNV). In 75% of the total of 120 trials a probe could be presented 1.5 sec prior to the WS interval, 0.5, 1, 1.5 or 2 sec after the onset of the 3 sec visual WS, and 3 sec following the imperative signal (WS offset, requiring a fast button press response), while 25% of the trials were without any probe. Only one probe occurred during a trial. The EEG was recorded along the midsagittal line; responses to the probes were evaluated by reaction time (RT) and probe-evoked potentials. RT to probes presented late in the anticipatory interval were speeded up and probe-evoked potentials were enhanced during this interval, in parallel to the development of the slow potential and the CNV in particular. Results suggest that probe stimuli presented during the development of the CNV were processed more intensely, thereby supporting the hypothesis that slow cortical potentials indicate the timing of excitability in cortical neuronal networks.(ABSTRACT TRUNCATED AT 250 WORDS)

Acoustic Stimulation↗