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Biomedical subjects

J Hahn

Publications and source records attributed to J Hahn.

At least 19 recordsLinked to original sources
PubMed1992

Frontal sinusitis with chronic epidural abscess: a case presentation.

The incidence of intracranial complications from acute frontal sinusitis has decreased with improved antimicrobial and surgical therapy. However, the physician must maintain a keen awareness and thoroughly investigate any possible signs of intracranial spread. This article discusses a case in which a chronic epidural abscess developed after inadequate therapy was rendered. It also reviews the presentation of and the factors leading to the development of intracranial complications. The treatment required is to eradicate the disease present and prevent future sinusitis.

Adolescent↗
PubMed1991

Immunological characterization of canine hematopoietic progenitor cells.

Canine hematopoietic progenitor cells were characterized by separation with monoclonal antibodies. Depleted and enriched fractions were studied for growth of CFU-GM in semisolid agar and for repopulating capacity of lethally irradiated dogs. CFU growth was not reduced by depletion of marrow using monoclonal antibodies F 3-20-7 (anti-dog Thy-1), MT606 (anti-human CD 6), and IOT2a (anti-human DR). CFU growth was variable following treatment with the anti-canine T-cell antibody MdT-P 1 and immunomagnetic bead separation. It was regularly enriched when MdT-P 1 treatment was followed by immunorosetting with staphylococcal protein A-loaded sheep red blood cells and density gradient separation. Lethally irradiated dogs were reconstituted by autologous marrow depleted of MdT-P 1-positive cells using immunorosetting and density gradient centrifugation, whereas immunomagnetic bead-depleted marrow was ineffective. Fluorescence-activated cell sorting showed enrichment of hematopoietic progenitor cells in the weakly MdT-P 1-positive fraction.

Animals↗
PubMed1991

Functional characterization of canine lymphocyte subsets.

Functional characterization of subsets of T lymphocytes is essential for transplantation studies in dogs, as it is in other species. We studied the function of T cells separated by two mouse monoclonal antibodies recognizing complementary subsets--an antibody directed to canine T cells (MdT-P1) with an up-regulating function, and an antibody directed to human CD 8 (MT811) that cross-reacts with down-regulating canine T cells. Immunorosetting with sheep red blood cells and Percoll gradient allowed us to study depleted and enriched fractions. Their function was tested in mixed lymphocyte culture (MLC), cell-mediated cytotoxicity (CML), and coculture with B cells in a hemolytic plaque assay (PFC). In MLC, MdT-P1-positive cells showed a high proliferative response, and MT811-positive cells responded poorly to allogeneic cells. Vice versa, MT811- negative cells responded strongly, and MdT-P1-negative cells were poor responders but strong stimulators. Effector cells of CML were separated following 8 days of culture and prior to mixing with target cells. Enriched and depleted fractions with either antibody showed low cytotoxic activity as compared with unseparated cells. When added to unseparated effector cells MT 811-positive cells suppressed cytotoxicity. B cells were obtained by rosetting with staphylococcal protein A (SPA). Their immunoglobulin production was studied following 6 days of culture stimulated by pokeweed mitogen in a reverse hemolytic plaque assay. Again, MT 811-positive cells added to the culture suppressed, and MT 811-negative cells enhanced immunoglobulin production. In conclusion, immunorosetting with two monoclonal antibodies allowed us to distinguish subpopulations of canine T cells with up-regulating (helper/inducer) from those with down-regulating (suppressor) activity.

Animals↗
PubMed1991

Cell-specific, developmentally and hormonally regulated expression of the rabbit uteroglobin transgene and the endogenous mouse uteroglobin gene in transgenic mice.

We have generated a transgenic mouse line by introducing the rabbit uteroglobin gene with 4 kb of 5'-flanking DNA and 1 kb of 3'-flanking DNA into the mouse germ line via microinjection into fertilized oocytes. Expression of the rabbit uteroglobin transgene was examined and compared with the endogenous mouse uteroglobin gene. Both genes are expressed in the lung, male genital tract and uterus. In the lung, mRNA expression is enhanced by glucocorticoids and restricted to the Clara cells that line terminal and respiratory bronchioli. During embryonic lung development, transcripts are first detected at day 17. Expression in the uterus is restricted to the glandular epithelium and can be induced by sequential treatment with estrogens and progesterone. In the uterus of these pseudopregnant mice the level of rabbit uteroglobin transcripts is higher than that of the mouse endogenous uteroglobin transcripts. In the male genital tract, expression of both genes is restricted to the epithelial layers of the vesicular gland, vas deferens and epididymis. Our results indicate that the rabbit uteroglobin gene together with 4 kb of 5'-flanking DNA and 1 kb of 3'-flanking DNA contains the information required for cell type-specific, developmentally, and hormonally regulated expression.

Animals↗
PubMed1991

Basal temporal language area.

Language interference was elicited by electrical stimulation of the dominant basal temporal region in 8 out of 22 cases and in none of 7 cases with subdural electrodes implanted over the nondominant temporal lobe. Language interference was elicited by stimulation of electrodes placed over the fusiform gyrus 3-7 cm from the tip of the temporal lobe. Electrical stimulation of the basal temporal language area produced a global receptive and expressive aphasia with speech arrest at high stimulus intensities. Other higher cortical function, for example copying complex designs or memory of nonverbal information was intact, in spite of the total inability to process verbal information. At lower stimulus intensities partial aphasias with a predominant receptive component occurred. Surgical resection of the basal temporal language area produces no lasting language deficit.

Adolescent↗
PubMed1991

Growth stage signal transduction and the requirements for srfA induction in development of competence.

srfA is an operon needed for the development of genetic competence in Bacillus subtilis. This operon is normally expressed at a low level during growth, and its transcription increases sharply just before the transition to stationary phase. The genetic requirements for the full expression of srfA were previously examined in several laboratories and shown to include spo0A, spo0H, spo0K, comQ, and comA. In the present study these results were confirmed with an isogenic set of strains. We have also shown that comP is needed for srfA expression but that other regulatory genes required for competence (degU, sin, and abrB) are not needed for the expression of srfA. We have used the expression of srfA under control of the regulatable Pspac promoter to study the kinetics of competence development and to determine whether the genes ordinarily required for expression of srfA are needed for any additional roles during the development of competence. When expression of srfA was driven from Pspac, competence was expressed constitutively throughout growth. Furthermore, when srfA was expressed from Pspac, the spo0K, comQ, comP, and comA determinants were no longer required for the expression of competence. We conclude therefore that the multiple signals which trigger the initiation of competence development in relation to growth stage are ordinarily received prior to the increase in srfA expression. We propose that these signals are mediated by the products of spo0K, comQ, comP, and comA, resulting in the phosphorylation of ComA by ComP. This in turn would enable ComA to function as a positive transcription factor for srfA, leading to the elaboration of the srfA product(s) and the consequent initiation of competence. We also propose that this is the major, and possibly the only, role for the spo0K, comQ, comP, and comA products during competence development.

Bacillus subtilis↗
PubMed1991

[Plinius and Greek physicians in Rome: the concept of nature and medical critique in Naturalis Historia].

Pliny's historical outline of the development of medicine, in Natural History 29.1-27, is our primary source concerning the reception of scientific medicine at Rome during the later Republic and early Empire. Here, as elsewhere, Pliny handles Greek doctors and their medical practices with vehement disapproval. But this attitude, at first glance anti-Hellene, traditionalistic, and critical of his coevals, arises from more deeply rooted notions: a specific conception of nature which can be shown to be the basis of Pliny's critique of medicine and his own times. Reconstruction of this "Plinean" conception reveals a view of nature marked by Stoic terminology and categories, though in fact derivate from various sources, idiosyncratic and characterized by a genuine love of and respect for nature and her creations. True comprehension of the lessons offered by nature, resulting in concrete mores of behaviour and moral categories, as opposed to theory and speculation, is the proper modus operandi for Pliny. And thus, with regard to the human process of self-discovery in the natural world, medicine plays a decisive role--for providential nature displays herself most clearly in the production of healing substances. Pliny notes among the proponents of scientific medicine, a general disregard for nature and her rules, while he finds just the opposite in traditional medicine. His own accomplishment resides not only in the safeguarding of numberless recipies from the world of folk medicine, but also in the facts that he under-pins these traditional methods of healing, and their basic principles, with a specific conception of nature, and that he marks out an exceptionally important place for traditional methods of healing in the canon of general knowledge.

Greece, Ancient↗
PubMed1990

Primary closure of infected spinal wounds.

Although postoperative infections of spinal wounds are uncommon, when they occur, they cause considerable morbidity. The classic treatment for deep infected wounds of the spine involves opening the wound, packing it, and permitting secondary closure to occur through granulation. A combined total of 10 patients with infected postoperative spinal wounds (two cervical and eight lumbar) from the Lahey Clinic and the Cleveland Clinic were treated by primary closure. Infection was diagnosed, usually within 2 weeks of operation (average, 10.9 days), by increasing back pain, purulent drainage from the incision, cultures, and subfacial extension of the process. In one patient, an associated disk space infection was observed. Causative organisms were Staphylococcus aureus in five patients and Staphylococcus epidermidis in five patients. At the second operation, the wounds were opened and radically debrided, irrigated, and closed primarily over one or two large drains. Treatment with intravenously administered antibiotics was continued postoperatively; the duration of treatment varied from 10 days to 6 weeks, depending on the presence or absence of involvement of bone or disks. Complete resolution of the infections and primary healing of the wounds occurred in all patients. This technique offers advantages over the traditional technique of secondary wound closure by decreasing the amount of wound care and length of hospitalization and is recommended as the treatment of choice for patients with postoperative spinal wound infections.

Adult↗
PubMed1990

Suppression of early competence mutations in Bacillus subtilis by mec mutations.

Although competence normally develops only in glucose-minimal salts media, mecA and mecB mutations permit the expression of competence and of late competence genes in complex media as well (D. Dubnau and M. Roggiani, J. Bacteriol. 172:4048-4055, 1990). The expression of late competence genes is dependent on the products of the regulatory genes comA, comB, comP, sin, abrB, spo0H, and spo0A. We show here that this list must be extended to include degU, csh-293, and spo0K. mecA and -B mutations bypass most of these requirements, making the expression of late competence genes and of competence itself independent of all of these regulatory genes, with the exceptions of spo0A and spo0K (in the case of mecB). The expression of late competence genes in mec mutants that are deficient for each of the bypassed regulatory functions is still under growth stage-specific regulation. The implications of these findings are discussed, and a provisional scheme for the flow of information during the development of competence is proposed.

Bacillus subtilis↗
PubMed1990

Decompression of the brain stem and superior cervical spine for congenital/acquired craniovertebral invagination: an interdisciplinary approach.

A transoropharyngeal/transpalatal approach to the clivus and anterior cervical spine in association with a midline labiomandibular glossotomy has proved successful in the treatment of craniovertebral instability. Nine cases at this institution between 1978 and 1986 were retrospectively reviewed. A head-and-neck surgeon, along with a neurosurgeon and/or orthopedic surgeon collaborated on these procedures. The indications, methods, operative techniques, results and postoperative complications are presented.

Adolescent↗
PubMed1990

Embryo transfer techniques.

At present, embryo transfer can be performed successfully in most of the mammalian species. There is a high degree of similarity concerning the reproductive functions in these species. In all species there are strong scientific and also practical reasons for the applications of embryo transfer and the associated techniques which will gain more importance in the future.

Animals↗
PubMed1990

[Histochemical and histomorphometric studies on growth fractions in human breast carcinoma].

Nucleolar organizer regions (NOR) can easily be recognized on paraffin sections of bioptic material with an argyrophilic stain. NORs are meant to to correlate with mitotic activity of proliferating cells. This study examine wether NOR-activity corresponds with the proliferations marker KI-67. 10 fibroadenomas and 40 invasive ductal breast carcinomas were studied. For objective tumor grading the size of the nuclei was determined morphometrically. NORs, KI-67 and nuclei sizes correlate closely in fibroadenomas. In carcinomas, however, a correlation between NORs, KI-67, and the size of the nuclei could not be found. NORs and KI-67 evidently mark different cell activities. For prognostic evaluation of malignant tumors they should therefore not be used alternatively but complementarily.

Breast Neoplasms↗