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Y Zohar

Publications and source records attributed to Y Zohar.

At least 91 records · Page 5Linked to original sources
PubMed1990

A rapid and sensitive ELISA for rainbow trout maturational gonadotropin (tGtH II): validation on biological samples; in vivo and in vitro responses to GnRH.

A rapid and sensitive heterologous enzyme-linked immunosorbent assay (ELISA) was developed to measure rainbow trout maturational gonadotropin. Purified salmon maturational gonadotropin (sGtH II) was used as reference hormone. Optimization of the procedure was performed by using an anti-beta sGtH serum. Two procedures were developed: an equilibrium assay (which did not involve a preincubation step) which lasted for 8 hr and a nonequilibrium assay (which involved a preincubation step) which lasted for 26 hr. The nonequilibrium assay gave the best sensitivity (70 pg/ml sample). GtH II measurements on in vivo and in vitro samples from GnRH analogs or sGnRH experiments showed that the ELISA procedure could be used over a wide range of concentrations. The method was validated by comparing GtH II concentrations measured by both RIA and ELISA.

Animals↗
PubMed1990

Degradation of gonadotropin-releasing hormones in the gilthead seabream, Sparus aurata. I. Cleavage of native salmon GnRH and mammalian LHRH in the pituitary.

The pattern and kinetics of degradation of native salmon gonadotropin-releasing hormone (sGnRH) and mammalian leuteinizing hormone-releasing hormone (LHRH) by pituitary bound enzymes were studied in the gilthead seabream, Sparus aurata. sGnRH and LHRH were incubated for different periods of time with membrane or cytosolic fractions of pituitary homogenates. At the end of the incubation, the degradation mixture was fractionated on reverse-phase high-pressure liquid chromatography. The degradation products were identified by comparing their retention times to those of synthesized GnRH fragments and by analyzing their amino acid composition. The main GnRH degradative activity resides in the cytosolic fraction of the pituitary homogenate. Both sGnRH and LHRH are rapidly degraded by pituitary cytosol, with 78.3 and 87.7% of the peptides, respectively, cleaved after 3 hr of incubation. Maximal degradation of sGnRH occurred at a pH range of 7 to 8. The main initial products of degradation of sGnRH and LHRH are the 1-5, 6-10, and 1-9 fragments. This suggests the involvement of two site-specific peptidases, a Tyr5-Gly6 endopeptidase and a Pro9-Gly10NH2 peptidase or postproline cleaving enzyme. While the 1-6 and 1-9 fragments undergo rapid secondary degradation, the 1-5 is relatively stable. Competition experiments suggest that the endopeptidase cleaving the sGnRH at the Tyr5-Gly6 bond is not specific to the neuropeptide and is probably a general proteolitic enzyme. However, the cleavage at the 9-10 bond has a high degree of specificity to the Pro9-Gly10NH2 sequence found in sGnRH. The two proposed pituitary peptidases of S. aurata have some characteristics similar to those of rat hypophyseal and hypothalamic GnRH cleaving enzymes. No differences are found in hypophyseal GnRH degradative activity between females with occytes undergoing previtellogenesis or advanced stages of vitellogenesis.

Amino Acids↗
PubMed1990

Degradation of gonadotropin-releasing hormones in the gilthead seabream, Sparus aurata. II. Cleavage of native salmon GnRH, mammalian LHRH, and their analogs in the pituitary, kidney, and liver.

The pattern and kinetics of degradation of native salmon gonadotropin-releasing hormone (sGnRH), mammalian luteinizing hormone-releasing hormone (LHRH), and some of their analogs by cytosolic enzymes of pituitary, kidney, and liver were studied in the gilthead seabream, Sparus aurata. The native peptides sGnRH and LHRH are rapidly degraded by all three tissues, LHRH being degraded faster than sGnRH. The kinetics of production of the peptide fragments suggest that initial cleavage of sGnRH and LHRH in the three studied tissues occurs at the 5-6 and 9-10 bonds. This indicates the initial activity of a Tyr5-Gly6 endopeptidase and a Pro9-Gly10NH2 peptidase or postproline cleaving enzyme. Secondary degradation of the main initial fragments (1-5, 6-10, and 1-9) is more intensive in the kidney than in the pituitary or liver. Substitution of the position 6 amino acid glycine by a dextrorotatory (D) amino acid such as in the D-Trp6-LHRH renders the 5-6 bond resistant to cleavage. However, whereas [D-Trp6]-LHRH is intensively cleaved at the Pro9-Gly10NH2 bond by the pituitary, its cleavage at this site by the kidney and liver is slow. This suggests a low activity of the Pro9-Gly10NH2 peptidase in the kidney and liver as compared to the pituitary. When, in addition to the position 6 substitution, the carboxy terminus Pro9-Gly10NH2 is modified to Pro9NET, such as in the [D-Ala6-Pro9NET]-LHRH and the [D-Arg6-Pro9NET]-sGnRH, the 9-10 cleavage site is also blocked, resulting in GnRH analogs highly resistant to degradation. The relationships between susceptibility of the different forms of GnRH to enzymatic degradation by the pituitary, kidney, and liver and their relative biological activities in S. aurata are discussed. We conclude that increased resistance of GnRH analogs to enzymatic degradation contributes to their superactivity.

Animals↗
PubMed1990

Nasopharyngeal pressure gradients during non-phonetic activities of the velopharyngeal valve. Part I.

The phonetic activity of the velopharyngeal valve has been the subject of electromyographic, radiological, ultrasonic, endoscopic, and of various acoustic and aeromechanical investigations. The subject of the present study was the non-phonetic activities of the velopharyngeal valve. Ten patients were assessed by nasendoscopic examinations of the velopharyngeal valve. The pressure gradients in the nasopharynx during these activities were recorded. Typical individual nasopharyngeal pressure patterns were revealed inducing a development of a special technique and tests for a further study of the non-phonetic activities of the velopharyngeal valve in correlation with its abnormality and pathological speech activities.

Adult↗
PubMed1990

Nasopharyngeal pressure gradients during non-phonetic activities of the velopharyngeal valve. Part II.

The subject of our study is the non-phonetic activities of the velopharyngeal valve (VPV). The VPVs of 10 patients were assessed by nasendoscopic examinations. The nasopharyngeal pressure fluctuations were recorded by catheters placed into the nasopharynx. Simultaneous pressure created in the oral cavity was measured as well. In Part I we discussed the swallowing activities and here we describe sucking and blowing activities. The pressure wave tracings and measurements with the nasendoscopic examination provide us with new information which permits a further study of the non-phonetic activity of the VPV and a correlation with its abnormal speech activity.

Adult↗
PubMed1990

Basaloid-squamous carcinoma of larynx metastatic to the skin of the nasal tip.

Basaloid-squamous carcinoma is a rare, highly malignant epithelial tumour with problematic histological characteristics and a poor prognosis. This unusual tumour has been described in the tongue, hypopharynx, and larynx. A unique case of basaloid-squamous carcinoma of the larynx metastatic to the skin of the nasal tip is presented. The literature regarding the histopathological and clinical aspects of basaloid-squamous carcinoma is reviewed.

Aged↗
PubMed1990

True malignant mixed tumour of the parotid gland.

Carcinoma ex-pleomorphic adenoma is an uncommon tumour of the parotid gland. True malignant mixed tumours of the parotid are rare and we could find only 14 such cases reported. A case of a 76-year-old man diagnosed as suffering from this entity is presented. The diagnosis was based on a series of immunohistochemical studies demonstrating the existence of two separate sarcomatous and carcinomatous elements. The clinical and histological data are presented and the literature is reviewed.

Adenoma, Pleomorphic↗
PubMed1990

Reduction of salivary flow with transdermal scopolamine: a four-year experience.

Scopoderm transdermal therapeutic system (TTS) is applied to prevent nausea and vomiting associated with motion sickness. Dry mouth is the most common side effect, appearing in up to two thirds of the patients treated. We have used this side effect to the benefit of patients with sialorrhea or with difficulties swallowing normally secreted amounts of saliva. More than 100 patients with tumors of the aerodigestive tract before and after surgery, and patients after parotidectomies, after tracheotomies, with peritonsillar abscesses, tonsillitis and pharyngitis, and neurologic disorders were thus treated. Reduced secretion of saliva was seen in 50% to 100% of the treatment groups. Other side effects were minimal and we recommend the use of scopoderm TTS for reduction of salivary flow.

Administration, Cutaneous↗
PubMed1990

Acute coronary events following cisplatin-based chemotherapy.

Six patients with no previous signs or symptoms suggestive of coronary artery disease developed acute coronary ischemia/infarction shortly after cis-diamine-dichloroplatinum II (cisplatin) -based chemotherapy. In two patients this was the sole chemotherapeutic agent used. One patient underwent coronary angiography which disclosed no pathology, but following which, while on a calcium channel blocking agent regimen, he had an uneventful course of chemotherapy with cisplatin. Documentation of cisplatin-related vascular events is important in view of the growing number of patients who undergo cisplatin-based chemotherapy.

Aged↗
PubMed1990

Ozena revisited.

Primary atrophic rhinitis or ozena is a chronic nasal disease characterized by progressive atrophy of the nasal mucosa and underlying bone, accompanied by the formation of foul smelling, thick, dry crusts in the greatly enlarged nasal cavities. Although the incidence of ozena is greatly diminished in the western world, it is still encountered rarely and merits the attention of the ENT specialist. Hereditary, infectious, developmental, endocrine and nutritional factors have been implicated but the etiology of ozena still remains enigmatic. Numerous surgical and non-surgical methods have been advocated for treatment of ozena. We review our experience with 17 ozena patients in the past 20 years and discuss different modes of treatment. The relevant literature is reviewed.

Adolescent↗
PubMed1990

Tuberculosis of a periglandular lymphnode presenting as a parotid tumor.

The presentation of tuberculosis as isolated cervical adenopathy is not a common entity. The presentation of this disease as a parotid mass has rarely been reported. In most instances, direct parenchymal involvement exists, although involvement of intraglandular lymphnodes has also been reported. In most cases, an initial misdiagnosis of a parotid tumor, usually a pleomorphic adenoma, was made. We report a case of a 57-year-old patient with a left parotid mass of two years' duration. The patient was referred because of the development of firm, nontender, ipsilateral cervical adenopathy, suggesting possible malignancy. The course of the disease, diagnosis, and treatment are reported. The relevant literature is reviewed.

Diagnosis, Differential↗