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Biomedical subjects

B Hirsch

Publications and source records attributed to B Hirsch.

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

Measurement of HPRT mutant frequencies in T-lymphocytes from healthy human populations.

Somatic cell mutant frequencies at the hprt locus of the X-chromosome were measured with the T-lymphocyte cloning technique in healthy human populations. A statistical analysis was performed of assays from 232 individuals (77 males and 155 females) ranging in age from 19 to 80 years. Data from 4 donor groups were compiled: (a) 132 participants in a study of identical and fraternal twins; (b) 17 health care workers studied as part of an assessment of the risks of handling chemotherapeutic drugs; (c) 62 women with benign breast masses; and (d) 21 normal laboratory and office personnel. The relationship between age and mutant frequency (MF) was expressed by the equation: ln MF = 1.46 + 0.018 age (P < 0.001). Thus, MF increased by about 2% per year. Increases in cloning efficiency (CE) reduced the MF, as shown in the equation: ln MF = 2.91 - 1.32 CE (P < 0.001). CE was significantly related to age (CE = 0.47 - 0.002 age, P = 0.038), and the interdependent relationship between MF, age and CE expressed by the equation: ln MF = 1.99 - 1.13 CE + 0.016 age was significant at the P < 0.001 level. There was no statistically significant effect of donor gender or smoking history on MF in our population, but CE was significantly lower in males (P < 0.001). These findings confirm the importance of age and CE as factors which influence the thioguanine-resistant MF in circulating T-lymphocytes from normal adults.

Adult↗
PubMed1993

Age and the self-perception of ability: a twin study analysis.

Two thousand nine hundred seventy-four adults, including 678 monozygotic and 547 dizygotic twin pairs, aged 27-86 years, self-rated ability on 6 factors: Interpersonal Competence, Workplace Skills, Trade Skills, Intellectual and Cultural, Domestic Skills, and Athletic Competition. Age accounted for no more than 2% of the variance on any factor, and, although there were significant gender effects, no significant Age X Gender interactions were observed. Twin similarity did not vary significantly with age, and biometrical variance component estimates were statistically homogeneous across age with talent factor variance being apportioned approximately equally to genetic and nonshared environmental factors. Consistent failure to find age effects as well as consistent observation of significant heritability support the conclusion that self-concept crystallizes early in adulthood and reflects genetically influenced psychological characteristics.

Adult↗
PubMed1993

In vivo measurement of rat ovarian collagenolytic activities.

Ovarian collagenases are necessary for the process of ovulation, and they are believed to be activated by the preovulatory LH surge. This information is largely based on in vitro investigations in which the balance between inhibitory and stimulatory principles involved in the activation of collagenase are largely disrupted. Therefore, we developed a simple and reliable method to measure collagenolytic activity in vivo in freely moving rats. By the use of a microdialysis system, a peptide coupled with methyl-coumarin is perfused into the bursa of the ovary. Collagenolytic enzymes cleave this peptide, and the cleaved fragments rediffuse into the microdialysis system. The effluent is collected in fractions, and the peptide-methyl-coumarin complex is cleaved, which results in liberation of fluorescent methyl-coumarin. This assay is linear over a wide range of collagenolytic activity, and other proteases, such as trypsin or plasmin, do not give any fluorescent signal. In proestrous rats, collagenolytic activity increases after the onset of the preovulatory LH surge. In animals in which the LH surge was disrupted by the surgical procedure but had a normal proestrous PRL surge, neither progesterone nor collagenolytic activity increased in the perfusate fluid. This indicates that it is only LH, not PRL, that activates follicular collagenolytic enzymes. Similar results were obtained in immature PMSG/hCG-treated animals. Using a well established zymographic assay, these results were confirmed, and it was further demonstrated that type I and type IV collagenase are active in the rat ovary.

Amino Acid Sequence↗
PubMed1993

Restoration of useful hearing after microvascular decompression of the cochlear nerve.

This report describes a patient with sudden sensorineural hearing loss who was found to have a megadolichoectasia vertebrobasilar system that appeared to be causing compression of the ipsilateral facial and vestibulocochlear nerves. The patient was treated conservatively for 4 months, during which time no hearing returned. He then underwent microvascular decompression of the affected nerves. At surgery, marked compression of the cranial nerves VII-VIII complex and the pons was observed. Postoperatively, the patient experienced a gradual return of useful hearing. We suggest that vascular compression may be a rare, but treatable, cause of sensorineural hearing loss.

Audiometry, Pure-Tone↗
PubMed1992

Amino acid neurotransmitter release in the preoptic area of rats during the positive feedback actions of estradiol on LH release.

To investigate the role of amino acid neurotransmitters in the regulation of LH secretion in ovariectomized (ovx) rats with or without estrogen substitution, we measured the release rates of gamma-aminobutyric acid (GABA), taurine, glycine, aspartate, glutamate, homocysteic acid, and also of the neurally inactive amino acids serine and glutamine in push-pull perfusate samples of the preoptic/anterior hypothalamic area (PO/AH) collected at 30-min intervals. To achieve this we had to develop a highly sensitive assay utilizing phenylisothiocyanate prederivatization which was followed by HPLC chromatography. In confirmation of our earlier results we observed again a conspicuous drop of preoptic GABA release prior to and during the time of estrogen-induced LH surge. In addition, the release rates of the excitatory amino acid neurotransmitters aspartate and glutamate in the PO/AH increased during this time. Interestingly, also secretion of taurine and glycine was increased during the LH surge, whereas preoptic release rates of serine and glutamine and of homocysteic acid, the putative endogenous ligand of the so-called N-methyl-D-aspartate receptor, remained unchanged. No such changes of amino acid neurotransmitters release rates were observed in ovx rats. This finding underlines that the changes of amino acid secretion in ovx estrogen-primed rats are likely due to the influence of the steroid rather than due to a diurnal rhythm. We conclude that GnRH neurons are under a tonic inhibitory tone exerted by GABA which is relieved during the time of the estrogen-induced LH surge. During this time, aspartate and glutamate may have additional stimulatory effects on GnRH neurons.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1992

Facial nerve repair by interposition nerve graft: results in 22 patients.

Resection of tumors of the posterior cranial base may incorporate a segment of the facial nerve because of tumor infiltration, or may result in unplanned nerve injury. Immediate repair of the facial nerve by resuture or with an autogenous nerve graft is highly desirable to ensure optimal recovery of facial function. Twenty-four patients who underwent extensive surgery of the posterior skull base and facial nerve reconstruction were studied. Of these, 12 patients had preoperative facial weakness and 3 had facial palsy. All patients underwent graft reconstruction from the subarachnoid or labyrinthine portion of the facial nerve to the fallopian or extracranial segment. The greater auricular nerve was used as a graft in 14 patients, and the sural nerve in 10. Two patients died of their disease soon after surgery, and, therefore, were excluded from our follow-up. In the remaining 22 patients, the median follow-up time was 20 months. As evaluated by the House-Brackmann grading system, 45% (10/22) of the surviving patients achieved a good recovery of facial function, 36% (8/22) attained a fair recovery, and 18% (4/22) had minimal or no recovery. There was no statistical correlation between the length of the graft used and the degree or timing of clinical recovery. The surgical result obtained in all patients with complete preoperative facial palsy and in one patient with dense facial paresis was poor.

Adolescent↗
PubMed1992

Temporal bone neoplasms: a report on 20 surgically treated cases.

The surgical resection of neoplasms involving the petrous bone and surrounding areas in 20 patients is reported. Technical advances described include the total resection of several tumors previously considered inoperable due to involvement of dura and brain, petrous internal carotid artery (ICA), the vein of Labbé, and adjacent areas such as the clivus and the cavernous sinus. Areas of reconstruction after resection included the ICA, the seventh and 11th cranial nerves, and the cranial base, often requiring the use of vascularized flaps. There were no intraoperative deaths. Many patients experienced significant temporary morbidity related primarily to wound healing and to lower cranial nerve palsy; however, all but three patients (all with fast-growing malignancies) returned to their preoperative functional status. During a median follow-up period of 30 months (range 17 to 63 months), the 10 patients with benign tumors and slow-growing malignancies fared well, seven being alive and disease-free. The 10 patients with fast-growing malignancies fared poorly, only two being alive without disease. This outcome appeared to be related to tumor pathology and extent of invasion; both survivors harbored tumors confined to the petrous bone. An anatomical classification system of tumor spread is introduced, which should be considered concomitantly with tumor pathology.

Adolescent↗
PubMed1992

Late course of preserved hearing and tinnitus after acoustic neurilemoma surgery.

The late course of preserved hearing and tinnitus following retrosigmoid transmeatal surgery for acoustic neurilemoma is reported. Over a period of 5 years, useful hearing was preserved in 15 patients after preservation was attempted in 42 patients. In five patients the hearing was better than the preoperative level; in three it was worse. Three patients developed delayed worsening and fluctuations of hearing in the surgically treated ear during a median follow-up period of 2 1/2 years. While the exact reason for such worsening was not clear in two patients, in one patient it appeared that the muscle graft placed in the internal auditory canal after tumor resection resulted in fibrosis and compromise of the cochlear nerve. The causes of delayed worsening of hearing in the absence of tumor recurrence are analyzed, and possible treatment and methods of prevention of worsening are suggested. In six patients, tinnitus persisted after surgery in the ear with successful preservation of hearing, but hearing was not worsened and the tinnitus was not bothersome to the patient. In one patient with preoperative tinnitus, hearing was not preserved and tinnitus persisted sufficiently to necessitate reexploration and cochlear nerve section.

Adult↗
PubMed1991

Sister chromatid exchanges are preferentially induced at expressed and nonexpressed common fragile sites.

To investigate the relationship between common fragile sites and sister chromatid exchange (SCE), lymphocyte cultures were treated with aphidicolin and bromodeoxyuridine (BrdU) and analyzed using a sequential G----SCE staining protocol. A total of 1,163 SCEs were mapped to their corresponding G-band sites, which were assigned to one of the following four categories: fragile sites expressed; fragile sites nonexpressed; nonfragile sites with breaks; or nonfragile sites with no breaks. The designated common fragile sites were found to be preferred locations for SCE formation, not only when these sites were "expressed" as visible gaps or breaks, but even when they were "nonexpressed" in the cell. SCEs were also more likely to occur at nonfragile sites with breaks than at nonfragile with no break sites. Further, SCEs were found to be distributed nonrandomly across fragile sites and nonfragile sites, and among the fragile sites, the high frequency SCE sites were highly correlated with the high frequency breakage sites. These data support the hypothesis of common steps in the mechanism of aphidicolin-induced SCE formation and common fragile site expression.

Adult↗
PubMed1991

Odontoma of the middle ear cleft.

Odontoma of the middle ear cleft is an unusual cause of conductive hearing loss. We report two cases and discuss the developmental mechanism by which this anomaly may occur. The differential diagnosis of calcified masses in the middle ear is also discussed.

Adult↗
PubMed1990

The three phases of time-limited day-hospital treatment.

The course of treatment in a time-limited day-hospital setting can be usefully understood in terms of three phases. Close examination of the treatment goals, difficulties, benefits, and tasks for both patients and staff for each phase provides a greater understanding of the curative process. These observations are based upon clinical work in a Veteran Administration Day Hospital and are reinforced with clinical examples from that work. Identification of these phases of treatment can be put to practical use. Knowing in which phase a patient is working helps staff members focus their thinking. Such an awareness can also help staff members cope with "burnout" over the frustrations that come with a particular phase. Information about these phases has been valuable to patients and their families in helping them understand the course of their treatment.

Adaptation, Psychological↗
PubMed1989

Development of an educational module for surgical training: a case study.

This paper describes the design of software that will be used as part of an interactive video programme for the training of otolaryngologists. Although the construction of the programme is still in progress, some insight is given into the process by which the ideas were first developed and the production and evaluation of the prototype software. The procedure chosen was stapedectomy.

Education, Medical, Continuing↗
PubMed1987

Sequential G- to R-banding for high resolution chromosome analysis.

A sequential staining protocol for revealing first G- and then R-bands on early metaphase chromosomes is presented. Lymphocyte cultures are synchronized with methotrexate, and released from the S-phase block with bromodeoxyuridine. The resulting early metaphase cells are initially G-banded with Wright's stain and then R-banded by the fluorescence plus Giemsa (FPG) technique.

Cells, Cultured↗
PubMed1987

Perilymph fistula resulting from microfissures.

Perilymphatic fistulas are well documented in the otolaryngologic literature as a cause for both auditory and vestibular symptoms. The anatomic location of fistulas has been clinically confirmed in both the oval and round windows. Furthermore, membranous tears within the cochlea have been described post mortem and may be the cause of the remaining fistulas which are suspected but not confirmed surgically. A fourth source of perilymph fistula has previously been suggested by Okano and Harada. During the past several years, surgical confirmation of perilymph leakage from two microfissure areas has been observed. These cases will be briefly discussed along with their clinical implications. Speculation as to the type of hearing loss caused by fistulas will be offered. Hypotheses concerning the various symptoms encountered in patients and the location of the defect will also be addressed.

Adult↗
PubMed1985

[Aqueous humor outflow capacity after argon laser trabeculoplasty. Preliminary report].

In a prospective study of 44 eyes with open angle-glaucoma and 27 with pseudocapsular glaucoma, the aqueous humor outflow facility was controlled for up to 12 months following argon laser trabeculoplasty (ALT). The average increase in the facility of outflow, which was 70% in open-angle glaucoma, was 25% higher in pseudocapsular glaucoma. In successful ALT, this increase in outflow facility was established within the first 20 hours after coagulation and did not decrease during the following year. There were no major complications such as transitory elevations of intraocular pressure, hyphema, or severe uveitis; this fact is interpreted as a result of the authors' technique, in which only the light-pigmented trabecular meshwork is coagulated.

Aqueous Humor↗
PubMed1984

Characterization of the distribution of sister chromatid exchange frequencies: implications for research design.

Mitoses from 21 individuals were examined to characterize the within and between subjects distributions of sister chromatid exchange (SCE) frequencies. The importance of accounting for both the within subjects and between subjects variability in the design and interpretation of research is demonstrated. A computer simulation study was performed to evaluate the estimate of an individual's mean SCE rate. A power analysis was performed using our transformed descriptive data to determine the percentage difference in SCE which could be detected between two groups (with 95% probability) as a function of both the number of mitoses per individual and the number of individuals in each group. Tables are provided as guidelines. Conclusions from our work include: (1) The empirical distribution of SCEs within an individual is best described by a negative binomial distribution; (2) The predominant source of variability in baseline SCE rates is between cells within a given individual rather than between individuals and can be accounted for in experiments by counting adequate numbers of mitoses per individual; and (3) There is a systematic relationship between the mean and SD for SCEs which should be removed prior to hypothesis testing by taking either a logarithmic transformation or square root transformation of the data.

Analysis of Variance↗