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Biomedical subjects

H A Miller

Publications and source records attributed to H A Miller.

At least 19 recordsLinked to original sources
PubMed1992

Dexamethasone stimulates release of an ANP-like substance from rainbow trout cardiocytes.

A substance that cross-reacts with antiserum to human atrial natriuretic peptide (ANP) is found in fish hearts. This ANP-like material increases sodium output from the gill and kidney while inhibiting sodium uptake in the gut. Mammalian ANP secretion is stimulated by glucocorticoids, and cortisol injection increases sodium output in salt-loaded fish. Therefore, we wanted to determine if the release of ANP in fish is sensitive to dexamethasone. Ventricle cardiocytes from the rainbow trout Oncorhynchus mykiss were treated with various doses of dexamethasone for 18 or 72 h. Single ventricle cells were then assayed for ANP release using a reverse hemolytic plaque assay and antiserum to human alpha-ANP. Incubation with 100 microM dexamethasone almost doubled the population of ventricle cells committed to ANP release (basal, 15.0 +/- 0.3% vs. Dexamethasone, 28.3 +/- 1.4%; values are percent plaque formation +/- SE). Stimulation of ANP secretion was dependent on dose and time of exposure to dexamethasone. These results suggest that ANP secretion in fish is regulated by glucocorticoids.

Animals↗
PubMed1990

Release of atrial natriuretic peptide from individual rat cardiocytes.

Atrial natriuretic peptide (ANP) is released from the atria and acts to regulate blood volume and pressure. The release of ANP appears to be stimulated by atrial distension, initiated by stretch on the cardiocytes. The purpose of the present study was to develop an assay that would allow for the detection of ANP release from single, isolated cells in the absence of distension. Using the reverse hemolytic plaque assay and antibody raised against human-alpha ANP, the release of ANP was detected from trypsin dissociated rat atrial cells. The specificity of the assay was demonstrated by a 67% reduction in ANP plaque forming cells detected following preabsorption of the anti-sera with rat-alpha ANP. The assay also proved efficient in monitoring changes in ANP secreting cell populations, where an acute treatment with dexamethasone resulted in a doubling of the percentage of atrial cardiocytes detected within a 4 hour antibody incubation. Finally, the assay established that about 52% of the dispersed atrial cardiocytes release ANP. The establishment of a plaque assay for ANP release should assist in addressing questions concerning what hormones may regulate ANP secretion directly and also allow for the determination of ANP secreting cell population dynamics.

Animals↗
PubMed1989

Ontogeny of prolactin secretion in the neonatal rat is regulated posttranscriptionally.

PRL-secreting cells first appear in appreciable numbers on day 4 of neonatal life in rats. In the present study, we attempted to ascertain whether the ontogenic appearance of PRL mRNA and hormone release were temporally coordinated or discordant. Our results show that the PRL gene is expressed at least 3 days before the onset of secretion in newborn rats. Moreover, steady state levels of PRL mRNA in neonates are at least as high as those found in 10-day-old rats, in which 15-17% of all pituitary cells secret the hormone. This apparent blockage of translation is attributable to a lack of association of PRL message with ribosomes in the neonate. Taken together, these data indicate that the ontogeny of PRL secretion in rats is regulated translationally as well as transcriptionally.

Animals↗
PubMed1988

Attenuation of growth hormone gene expression in desensitized somatotropes.

The effects of GRF-induced desensitization of somatotropes on GH gene expression were investigated on pituitary cells derived from male rats. Pretreatment of monodispersed cells for 18 hr with GRF abolished both the acute release of GH and the stimulation of GH gene expression in response to a subsequent 4 hr challenge with GRF. Concomitant preincubation with GRF and SS resulted in restoration of the ability of GRF to stimulate release of GH but not to augment GH gene expression. These results demonstrate that desensitization by GRF affects both the release of GH and GH gene expression, whereas the resensitizing effects of SS appear to be directed exclusively at the release mechanism.

Animals↗
PubMed1988

Evidence for a cAMP-dependent nuclear factor capable of interacting with a specific region of a eukaryotic gene.

Nuclear extracts prepared from the livers of rats treated with or without 8-bromo-cAMP were tested for their ability to bind to various fragments from the flanking region of the gene encoding phosphoenolpyruvate carboxykinase (GTP) [GTP: oxaloacetate carboxy-lyase (transphosphorylating), EC 4.1.1.32] known to contain the element that confers transcriptional regulation by cAMP. Using the nitrocellulose-filtration method, concentration-dependent, apparently saturable binding was seen that is both specific and cAMP dependent. Analysis of various fragments pinpointed the active binding region to positions within the -67 to -111 region, which coincides with the functional regulatory element as shown by recent transfection studies. Formation of an apparently single complex between a synthetic oligomer containing the region from -67 to -111 of the phosphoenolpyruvate carboxykinase gene and a factor in nuclear extracts from cAMP-treated rat liver was visualized by the gel-retardation method. Complex formation is both concentration and cAMP dependent and can be prevented by excess specific but not nonspecific competitor DNA. The congruity of the results with the two different methods suggests that the factor we have detected has properties consistent with a possible role as mediator of the transcriptional control exerted by cAMP in eukaryotic cells.

1-Methyl-3-isobutylxanthine↗
PubMed1988

Liver tissue from lactating rats produces a factor that stimulates prolactin release and gene expression.

Liver tissue from nursing rats produces a substance, termed liver lactogenic factor (LLF), that potently stimulates casein release from isolated mammary cells. Inasmuch as the production of LLF is dependent on PRL, we decided to determine whether it could influence the release of the hormone by dissociated pituitary cells in culture. This was accomplished by measuring PRL release with a reverse hemolytic plaque assay and PRL gene expression with a DNA probe complementary to PRL mRNA. Treatment of pituitary cells from day 10 lactating rats with liver slice incubates from the same type of animal caused a 35.3 +/- 4.3% increase in PRL release during a 3-h incubation. Likewise, the same dose of LLF activity markedly increased (3.5-fold) the steady state levels of PRL mRNA. The responses were reasonably specific for PRL, since neither GH plaque development nor gene expression was affected by identical treatment. Taken together these results demonstrate that LLF can act directly at the pituitary level to exert positive feedback effects on both PRL release and gene expression.

Animals↗
PubMed1987

Blunt liver trauma at Sunnybrook Medical Centre.

Between 1 June 1976 and 30 June 1985 Sunnybrook Medical Centre Regional Trauma Unit admitted 2,016 patients of whom 220 (11%) sustained liver injury. Of these 220 patients, 211 (96%) sustained blunt liver trauma; 175 of 176 patients who underwent open peritoneal lavage had a true positive lavage. Resuscitation was successful in 212 patients, of whom 209 underwent laparotomy and three were treated nonoperatively: 129 of 209 patients (62%) required only minor surgical treatment; the remaining 80 patients (38%) required major surgical procedures. The overall mortality was 29% (64/220). Eight patients died during resuscitation, one of them of liver hemorrhage. Of the 56 patients who died after admission, the cause of death was head injury in 31, liver hemorrhage in 11 (five intraoperatively) and 14 died of other causes. Overall, liver hemorrhage was the cause of death in 12 of 64 deaths (19%). In other words, 12 of the total of 220 patients (6%) died from liver-related mortality.

Accidents↗
PubMed1987

Abdominopelvic computerized tomography and open peritoneal lavage in patients with blunt abdominal trauma: a prospective study.

This prospective trial compares abdominopelvic computerized tomography and open peritoneal lavage in the diagnosis of blunt abdominal trauma. Fifteen patients (group 1) were evaluated by both methods. Another 15 patients (group 2) had only computerized tomography. Criteria for a "positive" scan were hemoperitoneum and evidence of solid organ injury. Criteria for "positive" lavage were a grossly bloody return, erythrocyte count greater than 20.0 X 10(9)/L and leukocyte count greater than 0.5 X 10(9)/L. At laparotomy, only injuries requiring repair or excision were considered "true positive". Patients who did not have laparotomy and had an uncomplicated clinical course were considered "true negative". With tomographic criteria alone for diagnosis there would have been one false-positive and three false-negative results, compared with three false positive and no false negatives for open peritoneal lavage alone. None of the three patients who had negative findings on laparotomy suffered any morbidity or died. Results of computerized tomography and open peritoneal lavage agreed in 8 of 15 patients (kappa value = 0.52), indicating a low level of agreement between the two. The authors believe that open peritoneal lavage remains the diagnostic procedure of choice in blunt abdominal trauma.

Abdominal Injuries↗
PubMed1986

Elastofibroma: chest wall pseudotumor.

A 68-year-old man had a painless, nontender lump in the right infrascapular region. An unenhanced computed tomography (CT) scan showed a soft-tissue mass attached to the scapula, causing muscular displacement. A similar, smaller mass was found on the left side. The appearance of the masses on CT scans was suggestive of infiltrating malignancy, but pathologic examination disclosed findings typical of elastofibroma. Biopsy is recommended in similar cases to exclude sarcoma.

Aged↗
PubMed1985

Analysis of peritoneal lavage parameters in blunt abdominal trauma.

Peritoneal lavage is the most valuable diagnostic modality presently available for the evaluation of patients with blunt abdominal trauma. A retrospective review of 523 patients who underwent open peritoneal lavage for blunt abdominal trauma over a 3 1/2-year period revealed serious intra-abdominal pathology in 83% of patients undergoing laparotomy with RBC lavage counts in the range of 20,000 to 100,000 cells/mm3, a level considered by many authors to be negative or indeterminate. Two patients with isolated small bowel perforations had an elevated amylase level as the only measured abnormality. The data indicate that the standard guidelines for RBC positivity (positive count greater than 100,000 cells/mm3 and indeterminate count 50,000 to 100,000 cells/mm3) result in missed intraperitoneal injuries in a large percentage of patients and therefore require reevaluation. Lavage amylase determinations, previously stated to be costly and of insignificant yield, should be performed on patients whose lavage would otherwise be considered negative by RBC and WBC counts.

Abdominal Injuries↗
PubMed1985

Blunt liver trauma at the Sunnybrook Regional Trauma Unit.

Between June 1, 1976 and Mar. 31, 1983, the Sunnybrook Medical Centre Regional Trauma Unit in Toronto, Ont., admitted 145 patients with liver trauma; of these, 141 (97%) had sustained blunt liver trauma. Of 113 patients who underwent open peritoneal lavage, 112 had a true-positive lavage. Resuscitation was successful in 137 patients and 134 of these underwent laparotomy. Seventy-nine (59%) of the 134 patients required only minor surgical treatment; the other 55 (41%) required major surgical procedures. The overall mortality was 32% (47 of 145). Eight patients died during resuscitation but only one of them died of liver hemorrhage. Of the 39 patients who died after admission, the cause of death was head injury in 22, while 6 died of liver hemorrhage and 11 of other causes. Overall, liver hemorrhage was the cause of death in 15% of cases (7 of 47).

Female↗
PubMed1979

Therapy for septic shock.

To adequately appraoch the therapeutics of such a diffuse disorder as sepsis, a firm grasp of the multiple pathophysiologic subsets is imperative. With this as a basis, therapy comes as close to applied physiology as is possible in medicine today.

Acid-Base Equilibrium↗
PubMed1977

Echocardiography in cystic fibrosis.

Echocardiograms were obtained for 25 patients with cystic fibrosis (CF) and 20 controls to evaluate this technique as a means of assessment of right ventricular changes in patients with CF. Right ventricular anterior wall thickness per square meter of body surface (RVAW/sq m) and right ventricular internal dimension per square meter of body surface (RVID/sq m) were compared with other techniques for detection of cor pulmonale. Significant correlations existed between both RVAW/sq m and RVID/sq m and the forced vital capacity, forced expiratory volume in one second, midmaximal expiratory flow rate, clinical score of severity of disease, and roentgenographic score of pulmonary involvement. The RVAW/sq m was slightly more sensitive than RVID/sq m; RVAW/sq m thickness on echocardiogram in vivo compared well with actual measurements at autopsy in five patients. No correlations were found between echocardiography and electrocardiograms, vectorcardiograms, thoracic index, or cardiothoracic ratio.

Adolescent↗
PubMed1977

[Reliability of electrophysiologic examinations for cataract surgery in cases of suspected retinal detachment].

Justification for cataract surgery obviously depends on retinal efficiency. The study of light projections makes it sometimes possible to suspect a retinal detachment. We are, therefore, trying to check for retinal detachment by means of the various exploration processes now available. Results of echography, electroretinography, electro-oculography, and visual evoked potentials are discussed according to the exper-ence gained.

Cataract↗