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Biomedical subjects

M Peterson

Publications and source records attributed to M Peterson.

At least 91 records · Page 5Linked to original sources
PubMed1995

Combined spinal-epidural anesthesia for outpatient surgery. Dose-response characteristics of intrathecal isobaric lidocaine using a 27-gauge Whitacre spinal needle.

BACKGROUND: Combined spinal-epidural anesthesia (CSE) may offer theoretic advantages for outpatient surgery, because it produces the rapid onset of spinal anesthesia, with the option to extend the blockade with an epidural catheter. In this study, the authors attempted to determine an appropriate initial dose of a short-acting local anesthetic, 2% lidocaine, to administer for outpatient knee arthroscopy using CSE. METHODS: Data were collected from 90 patients undergoing outpatient knee arthroscopy. Using a double-blinded, prospective study design, patients were randomly assigned to receive CSE with an initial dose of intrathecal 2% lidocaine of 40, 60, or 80 mg. A 27-G 4 11/16-inch Whitacre needle was placed through a 17-G Weiss needle. Onset and regression of sensory anesthesia and motor blockade were measured by a blinded observer at frequent intervals. RESULTS: All 90 patients had adequate anesthesia. Durations of thoracic and lumbar sensory and lower limb motor blockade were significantly shorter in the 40-mg group compared with the 60- or 80-mg groups (P < 0.0002 Mantel-Cox, Survivorship Analysis). Indices of neural blockade resolved 30-40 min more rapidly in the 40-mg group than in either the 60- or 80-mg group. Times to urinate, site upright in a chair, take oral fluids, and be discharged were all significantly shorter (between 30 and 60 min) in the 40-mg group compared with the 60- and 80-mg groups (P < 0.01). Seven patients required intraoperative epidural supplementation: three in the 40-mg group, three in the 60-mg group, and one in the 80-mg group. CONCLUSIONS: Combined spinal-epidural anesthesia with a 40-mg initial intrathecal dose of lidocaine provided reliable anesthesia for knee arthroscopy. Duration of spinal anesthesia with lidocaine was dose related.

Adolescent↗
PubMed1995

Temporal regulation of the Xenopus FGF receptor in development: a translation inhibitory element in the 3' untranslated region.

Early frog embryogenesis depends on a maternal pool of mRNA to execute critical intercellular signalling events. FGF receptor-1, which is required for normal development, is stored as a stable, untranslated maternal mRNA transcript in the fully grown immature oocyte, but is translationally activated at meiotic maturation. We have identified a short cis-acting element in the FGF receptor 3' untranslated region that inhibits translation of synthetic mRNA. This inhibitory element is sufficient to inhibit translation of heterologous reporter mRNA in the immature oocyte without changing RNA stability. Deletion of the poly(A) tract or polyadenylation signal sequences does not affect translational inhibition by this element. At meiotic maturation, we observe the reversal of translational repression mediated by the inhibitory element, mimicking that seen with endogenous maternal FGF receptor mRNA at meiosis. In addition, the activation of synthetic transcripts at maturation does not appear to require poly(A) lengthening. We also show that an oocyte cytoplasmic protein specifically binds the 3' inhibitory element, suggesting that translational repression of Xenopus FGF receptor-1 maternal mRNA in the oocytes is mediated by RNA-protein interactions. These data describe a mechanism of translational control that appears to be independent of poly(A) changes.

Animals↗
PubMed1994

Genomic sequence sampling: a strategy for high resolution sequence-based physical mapping of complex genomes.

We present a simple and efficient method for constructing high resolution physical maps of large regions of genomic DNA based upon sampled sequencing. The physical map is constructed by ordering high density cosmid contigs and determining a sequence fragment from each end of every clone. The resulting map, which contains 30-50% of the complete DNA sequence, allows the identification of many genes and makes possible PCR amplification of virtually any part of the genome. We apply this strategy to the automated analysis of the genome of the primitive eukaryote Giardia lamblia and evaluate its applicability to the physical mapping and DNA sequencing of the human genome.

Amino Acid Sequence↗
PubMed1994

Pathogenesis of pulmonary fibrosis: platelet-derived growth factor precedes structural alterations in the Hermansky-Pudlak syndrome.

Peptides that modulate mesenchymal cell function have been detected in the fibrotic lung disorders once physiologic dysfunction is present. Despite this close association with manifest disease, their role in initiating alveolar remodeling remains unknown. We examined the hypothesis that one potent peptide, platelet-derived growth factor (PDGF), would be present at the alveolar surface before the onset of physiologic dysfunction in patients in whom pulmonary fibrosis subsequently develops. Bronchoalveolar lavage and physiologic assessment were performed in asymptomatic patients with the Hermansky-Pudlak syndrome (n = 30), obligate heterozygous (n = 9), and normal volunteers (control group). Lavage cell number and profile were normal, but alveolar macrophages demonstrated characteristic autofluorescence and ultrastructural features of ceroid. Lavage fluid from physiologically normal patients with Hermansky-Pudlak syndrome and from those with occult restrictive disease demonstrated two PDGF-related peptides (14 kd and 38 kd). Radioligand binding and fibroblast proliferation assay demonstrated that the peptides were functional. By immunoassay the concentration of PDGF in lavage fluid was six times greater than control values (p < 0.01). In situ hybridization together with bioassay indicated that alveolar macrophages were one cellular source of PDGF. Similar results were obtained for heterozygotes. These data identify macrophage-derived PDGF peptides as important candidate molecules in the initiation of alveolar remodeling in the fibrotic lung disorders.

Adolescent↗
PubMed1994

Successful aging: how to help your patients cope with change.

Collaborative work between physicians and social workers can be very valuable in helping patients to "age successfully." For many patients, the medical consequences of chronic disease are compounded by social problems, such as isolation and loss of self esteem. Social workers attempt to help people cope with the stresses of aging by gaining some degree of control over their lives. Keys to successful aging include being flexible and adaptable in the face of change, being connected in a confidante relationship with at least one other person, and feeling that life has a purpose beyond mere survival. Social workers provide such mental health services as counseling, support, and conflict resolution. They can also assist in the time-consuming work of finding needed community resources.

Adaptation, Psychological↗
PubMed1994

Physical aspects of aging: is there such a thing as 'normal'?

Traditional thinking about the process of aging is changing as the distinction blurs between normal aging and disease. One of the myths about aging is that all older people are alike. However, one of the maxims of geriatrics is that as people get older they become less alike. Several models have been proposed for the interactions between aging and disease. Although the issue of distinguishing normal aging from disease poses challenges in the clinical setting, the inclusion of aging into the equation can also make the care of older persons more intellectually stimulating.

Aged↗
PubMed1993

The chondroitin sulfate form of invariant chain can enhance stimulation of T cell responses through interaction with CD44.

Invariant chain (Ii) is a nonpolymorphic glycoprotein that associates with major histocompatibility complex class II molecules and has been shown to mediate several functions in class II-restricted antigen presentation. A small proportion of Ii is modified by the addition of chondroitin sulfate (Ii-CS), and this form of Ii is associated with class II on the surface of antigen-presenting cells. In this report we show that expression of Ii-CS dramatically enhanced the ability of class II-positive EL4 transfectants to stimulate class II-dependent allogeneic and mitogenic T cell responses. Antibody blocking studies and the ability of CD44 to bind directly to Ii-CS suggest that Ii-CS can function as an accessory molecule during T cell responses through interactions with CD44.

Animals↗
PubMed1993

Adrenalectomy and castration in the genetically obese (ob/ob) mouse.

The present studies have tested the hypothesis that adrenalectomy could modify the phenotypic expression of genetic obesity by examining the effects of adrenalectomy on the function of the gonadal system in lean and ob/ob mice. Corticosterone concentrations were undetectable in the adrenalectomized animals. Adrenalectomy significantly slowed the weight gain of obese mice in comparison to sham-adrenalectomized controls. Gonadectomy had no independent effect on weight gain. The testes, prostate, and seminal vesicles in the ob/ob mice were significantly smaller than in the lean animals. Castration lowered the weights of the prostate and seminal vesicles in the lean mice to weights close to those observed in the castrated ob/ob mice. Castration significantly increased the concentrations of LH and FSH in both ob/ob and lean mice, but the absolute concentrations were higher in the lean mice in both conditions. Adrenalectomy per se had no effect on the concentration of LH, FSH, or testosterone or on the weights of the prostate or seminal vesicles. These data indicate that adrenalectomy has no effect on the physiologic control of the reproductive system in genetically obese mice, and are consistent with the hypothesis that the defect in the ob/ob mouse is a modulator of steroid action which over expresses glucocorticoid effects and under expresses gonadal steroid effects.

Adrenal Glands↗
PubMed1993

Validity of register data on acute myocardial infarction and acute stroke: the Skaraborg Hypertension Project.

In the evaluation of a hypertension treatment program, the end-point surveillance included incidence of acute myocardial infarction and acute stroke identified from hospital in-patient registers and the national mortality register. To ascertain the validity, in-patient records containing the ICD-codes 410-411 and 430-438 were validated. First event of acute myocardial infarction and acute stroke suggested in the in-patient register could be confirmed in 96% and 94%, respectively. In-patient diagnoses of suspected acute myocardial infarction or other acute or subacute ischemic heart diseases, transient ischemic attack and unspecified heart diseases, transient ischemic attack and unspecified cerebrovascular disease revealed high proportions of what in fact turned out to be definite events (11%, 24% and 53% respectively). It is concluded that disease ascertainment for this cohort study claims validation of register data with hospital records.

Acute Disease↗
PubMed1993

Factors influencing deep vein thrombosis following total hip arthroplasty under epidural anesthesia.

To determine intraoperative factors which may influence deep vein thrombosis rate, we studied surgeries performed by one surgeon on 441 consecutive patients undergoing primary total hip arthroplasty under epidural anesthesia. Operative limb venography was performed on the fourth or fifth postoperative day in 381 patients, who received 650 mg of aspirin daily as the only postoperative thromboprophylaxis. Of 381 (15%) patients, 58 had a positive venogram; 13 (3%) had proximal thrombi. Of 178 patients (9.5%) with surgery lasting less than 70 min, 17 developed deep vein thrombosis whereas 41 of 203 patients (20.3%) with surgery lasting more than 70 min developed deep vein thrombosis (P < 0.05). Corresponding proximal deep vein thrombosis rates increased from 1.7% to 4.9%. Deep vein thrombosis was observed in 12.5% of patients receiving intravenous low-dose epinephrine, 10.3% receiving intravenous sodium nitroprusside, 14.5% receiving both low-dose epinephrine and sodium nitroprusside concurrently, and 25% receiving intravenous fluid alone. Proximal deep vein thrombosis rates were 2.4%, 0%, 1.45%, and 9.3% in these groups, respectively. These data suggest that the intraoperative management of both surgery and anesthesia influence rates of deep vein thrombosis following total hip arthroplasty.

Adolescent↗
PubMed1993

Macrophage production of basic fibroblast growth factor in the fibroproliferative disorder of alveolar fibrosis after lung injury.

In organ repair following injury, macrophages accumulate and granulation tissue, comprised of fibroblasts and endothelial cells, develops in the injured area. Basic fibroblast growth factor (bFGF), a potent stimulator of fibroblast and endothelial cell growth, has been linked to the fibroproliferative process. Macrophages are thought to play a central role in the fibroproliferative response, and prior studies indicate that they produce bFGF. Whereas it is plausible that macrophages produce bFGF in a fibroproliferative process, currently no data exists that directly identifies the macrophage as a source of bFGF in a fibroproliferative disorder. We used the model of acute intraalveolar granulation tissue formation following lung injury to determine if the macrophage was a cellular source of bFGF in a naturally occurring fibroproliferative process. To examine this hypothesis, patients with severe acute lung injury underwent bronchoalveolar lavage during the phase of lung repair. Polymerase chain reaction and Northern analysis of macrophage RNA revealed the presence of two species of bFGF messenger RNA (4.4 kb and 1.9 kb). Metabolic labeling studies of recovered macrophages revealed a newly synthesized 18-kd protein with antigenic similarity to bFGF. Immunohistochemical evaluation of lung tissue from patients who died following acute lung injury, showed numerous bFGF immunoreactive macrophages present within airspaces containing fibroblastic and vascular tissue proliferation. This investigation has identified the alveolar macrophage as a cellular source of bFGF in the fibroproliferative disorder of intraalveolar fibrosis following acute lung injury.

Autoradiography↗
PubMed1992

Antigen presentation enhanced by the alternatively spliced invariant chain gene product p41.

During biosynthesis, class II molecules of the major histocompatibility complex are associated with a nonpolymorphic protein called invariant chain, Ii, which facilitates folding of class II molecules and their exit from the endoplasmic reticulum, interferes with their association with peptide and directs their post-Golgi transport (refs 7-9). If Ii blocks class II loading with endogenous antigens in the endoplasmic reticulum and/or directs class II molecules to the exogenous antigen-loading compartment, then the co-expression of Ii should enhance the ability of class II molecules to present exogenous antigens to T cells. But data supporting a role for Ii in class II-restricted antigen presentation are controversial. Here we show that Ii can facilitate exogenous antigen presentation for a subset of antigens. Although all known functions of Ii have been ascribed to the principal form of Ii, p31, we find that in most cases antigen presentation is facilitated only by the alternatively spliced, minor form of Ii, p41.

Animals↗
PubMed1992

The voluntary dissemination of performance information by health care organizations.

This paper examines the factors that influence the voluntary dissemination of performance information by health care organizations. A model of information dissemination is developed and tested using data on Health Maintenance Organizations. The empirical findings suggest that health care organizations disseminate information on their performance because there are collective-good benefits resulting from dissemination, particularly when the product or organizational innovation is unfamiliar to some purchasers. The findings also suggest that the competitive structure of the local health care market influences the dissemination decision, with health care organizations more likely to disseminate information about their performance in relatively competitive markets.

Catchment Area, Health↗
PubMed1992

Topical indomethacin in the treatment of chronic cystoid macular edema.

Eighty percent of 30 eyes with chronic cystoid macular edema (CME) after cataract extraction achieved improved visual acuity of three or more lines when treated with 1% indomethacin eye drops. Of these patients 53% demonstrated an "on/off" phenomenon induced by the initiation and cessation of treatment documented by visual acuity measurements and fluorescein angiography. This "on/off" phenomenon suggests that there is a direct relationship between the use of 1% indomethacin eye drops and the resolution of chronic CME after cataract extraction. Previous studies on the treatment of CME with indomethacin have not addressed the use of indomethacin eye drops for chronic CME.

Administration, Topical↗
PubMed1992

A screening and counseling program for prevention of osteoporosis.

Prevention of osteoporosis is an increasingly salient public health concern as our society ages. This report describes the procedures used at an osteoporosis center to which people come for screening and counseling. The patients on whom this report is based were 53 non-smoking women, 1-10 years postmenopausal at the time of their first visit to the center, who chose not to undertake estrogen therapy, and who returned for a second visit in 12-18 months. They were classified as to adequacy of calcium intake (at least 750 mg/day) and exercise (at least 3 h/week of weight-bearing exercise) at both visits; complete data on calcium intake and exercise were available on 46 of the women. Bone densities were measured at the femoral neck and lumbar spine with dual energy X-ray absorptiometry, and at the distal radius with single photon absorptiometry. At the first visit, 67% of the women reported adequate exercise and 43% reported adequate calcium intake. At the second visit, the percentages in the adequate categories had increased to 74% for exercise (p = 0.06) and 70% for calcium intake (p = 0.02). Age at the first visit was inversely correlated with femoral (r = -0.40, p = 0.003) and spinal (r = -0.36, p = 0.009) bone densities; the correlation with radial bone density did not achieve significance (r = -0.27, p = 0.55). Rather than declining, as would be expected in early postmenopausal women, bone density rose slightly, but not significantly, between visits for all three sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1992

Mesenchymal cells isolated after acute lung injury manifest an enhanced proliferative phenotype.

After acute lung injury, mesenchymal cells migrate into the alveolar airspace where they proliferate and deposit connective tissue macromolecules. Early in the disease process, inflammatory cell-derived trophic factors modulate these mesenchymal cell functions. However, in those patients who die, even as the inflammatory response abates, the fibroproliferative response continues, resulting in extensive intraalveolar fibrosis. We therefore hypothesized that lung mesenchymal cells obtained from individuals dying with acute alveolar fibrosis would manifest an enhanced proliferative capacity that was independent of persistent exogenous signals. To examine this hypothesis, the in vitro growth properties of mesenchymal cells prepared from patients dying with acute lung injury (n = 3) were analyzed in defined medium and compared with those of mesenchymal cells similarly prepared from patients dying with histologically normal lungs (n = 3). Isolates were characterized as mesenchymal cells by using morphological and immunohistochemical criteria. In accord with the hypothesis, mesenchymal cells isolated from lung-injured patients doubled within 3 d in the complete absence of exogenous peptide growth factors, reaching a saturation density of approximately 15 x 10(3) cells/cm2. As expected, lung mesenchymal cells from normal individuals failed to significantly increase in number. Consistent with this proliferative phenotype, the immediate early cell division cycle genes c-fos and c-jun were constitutively expressed in each cell strain prepared from injured lungs, but not in those from control lungs. The observed proliferative phenotype was stable through the fifth subcultivation of the cells. Despite these proliferative properties, three separate criteria indicated the mesenchymal cells from injured lungs were not transformed: normal karyotype; finite lifespan in vitro (9-10 subcultivations); and inability to disseminate in mice with severe combined immunodeficiency. These data support the hypothesis that mesenchymal cells manifest an enhanced proliferative state after acute lung injury.

Acute Disease↗
PubMed1992

Induction of azoospermia in normal men with combined Nal-Glu gonadotropin-releasing hormone antagonist and testosterone enanthate.

The effects of a combined GnRH antagonist and testosterone (T) replacement regimen on gonadotropins and spermatogenesis were examined to assess its potential as a male contraceptive regimen. The potent Nal-Glu GnRH antagonist ([Ac-D2-Nal1,D4-Cl-Phe2,D3-Pal3,Arg5, D4-p-methoxybenzoyl-2-amino butyric acid6,D-Ala10]GnRH) was administered daily (7.5 mg, sc) to eight normal men for 16 weeks. T enanthate was given im starting at week 2 and every 2 weeks thereafter through week 14 of the treatment phase. Serum LH, FSH, T, and estradiol concentrations were measured frequently during the 5-week control period, the 16-week treatment phase, and the 14-week recovery phase. Semen analyses were performed every week during the control phase and every 2 weeks during the treatment and recovery phases. Seven of eight subjects became azoospermic by 6-10 weeks of treatment; the eighth subject, who failed to achieve azoospermia, suppressed his sperm count to 7 million/mL by week 14 (from a mean baseline of 42 million/mL) before treatment was prematurely terminated because of localized swelling at each of his injection sites. Sperm counts returned to baseline 10-14 weeks after the end of Nal-Glu administration. Seven of the eight subjects showed suppression of LH to the limit of assay detection (less than 0.2 U/L), whereas the eighth subject showed incomplete suppression. Serum bioactive and immunoreactive LH concentrations showed concordant responses. Mean serum FSH concentrations were also markedly suppressed. Serum T and estradiol concentrations declined dramatically during the first 2 weeks of Nal-Glu GnRH treatment, but returned to the normal physiological range after T enanthate replacement was initiated. Libido and sexual potency were maintained. No systemic side-effects, other than erythema and induration at injection sites, were observed. These data demonstrate that combined GnRH antagonist plus T treatment can predictably and reversibly induce azoospermia in most men and has potential as a male contraceptive regimen.

Adult↗