PubMed Health⌕ Search

Biomedical subjects

S Freed

Publications and source records attributed to S Freed.

35 records · Page 2Linked to original sources
PubMed1975

Separation of cholinergic proteolipids from quenched rat cerebral cortex and resolution of properties at low temperature.

Proteolipids from rat cerebral cortex quenched at -196 degrees C were extracted and fractionated at subzero temperature (-60 degrees C). On Sephadex LH-20 column chromatography, acetylcholine and cholinergic blocking agents such as dimethyl-d-tubocuratine and decamethonium were observed to bind to different fractions of proteolipids showing that the receptor fractions for acetylcholine and that for cholinergic blockers need not be the same. The acetylcholinesterase (EC 3.1.1.7) activity was demonstrated to be absent in both types of receptor fraction. The specificities of binding by cholinergic substances to proteolipid fractions prepared at -60 degrees C persisted at room temperature with some loss in specificity for acetylcholine. Since these specificities were not observed in previously reported experiments at room temperature, it appears that the structures of proteolipids extracted at the two temperatures differ. The appearance of specificities in the proteolipids prepared at low temperature suggest that their structures are in better approximation to those in vivo that presumably are highly specific. The importance of the protein moiety of proteolipids as a discriminator for the neurotransmitter is discussed.

Acetylcholine↗
PubMedDate not supplied

Assessment of fine needle aspiration as a screening test for occult prostatic carcinoma.

As part of an ongoing study of objective parameters of prognostic value in prostatic carcinoma, a routine procedure was developed to aspirate all prostates prior to surgery. These targets were different from those of other workers in the field of prostatic fine needle aspiration (FNA), who generally advocate that FNA be confined to suspicious nodules. The aspirations were performed by a large group of practicing urologists who had no special training in prostatic FNA except for guidelines provided by their peers and information available in the literature. This approach permitted an assessment of the performance of FNA as a screening test rather than as a diagnostic procedure. During the period from January 1983 to February 1987, 1,683 patients had prostatic FNAs performed (plus subsequent histologic study). The following diagnoses were rendered: "inadequate/scanty specimen" in 625 cases (37%), "negative/atypical" in 844 cases (50%) and "suspicious/positive" in 214 cases (13%). Histologic examination showed stage A1 prostatic adenocarcinoma in 18 patients. The cytologic diagnoses on these 18 patients were inadequate/scanty in 3 (17%), negative/atypical in 13 (72%) and suspicious/positive in 2 (11%). Of the 214 patients with a positive/suspicious diagnosis by FNA, the diagnosis of prostatic carcinoma was confirmed by tissue evidence in 200; the other 14 patients had either no evidence of prostatic carcinoma on surgical biopsy (needle biopsy/transurethral resection/suprapubic prostatectomy) or had no surgical biopsy. Eight of the 14 patients developed clinical evidence of carcinoma, 1 died of urinary bladder carcinoma and 1 was lost to follow-up. In the remaining four patients, there is still no evidence of prostatic carcinoma after about one-and-one-half years of follow-up. These results indicate that (1) specialized training is required in order to obtain adequate smears by prostatic FNA; (2) prostatic FNA is not a good screening technique for detecting stage A1 prostatic carcinoma; and (3) a positive diagnosis by prostatic FNA, even when not confirmed by tissue biopsy, is still an indication of disease.

Adenocarcinoma↗