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Biomedical subjects

R H Miller

Publications and source records attributed to R H Miller.

At least 199 records · Page 11Linked to original sources
PubMed1991

Immunohistochemical properties of human optic nerve glioma. Evidence of type 1 astrocyte origin.

The peroxidase-antiperoxidase method was used to study ten surgically obtained human optic nerve gliomas (pilocytic astrocytomas). All tissues were formalin fixed and paraffin embedded. Primary antisera included glial fibrillary acidic protein (GFAP), HNK-1 (type 1 astrocyte precursor marker), A2B5 (type 2 astrocyte precursor marker), S-100, vimentin, myelin basic protein (MBP), laminin, keratin, cytokeratin, epithelial membrane antigen (EMA), and neuron-specific enolase (NSE). Neoplastic astrocytes in optic nerve gliomas stained with GFAP, HNK-1, S-100, and vimentin. Oligodendrocytes and myelin sheaths stained for MBP, and NSE stained surviving axons in the tumors. Neoplastic astrocytes did not stain for A2B5, keratin, cytokeratin, EMA, or laminin. These results suggest that human optic nerve gliomas (pilocytic astrocytomas) arise from type 1 astrocytes.

Astrocytes↗
PubMed1991

Subglottic stenosis.

Subglottic stenosis, a laryngeal narrowing, can be either congenital or acquired. There are various anatomic abnormalities of the cricoid that explain the congenital types. The acquired type is due to prolonged intubation in 90% of cases. Anterior cricoid split can obviate the need for a tracheotomy in the neonate with minimal nonfibrotic subglottic stenosis. Laryngotracheal reconstruction allows correction of the more severely stenotic children. Both of these procedures strive to provide an adequate airway and a satisfactory voice.

Child↗
PubMed1991

Nasopharyngeal carcinoma.

Carcinoma of the nasopharynx is a rare disease that presents the physician with a difficult diagnostic and therapeutic challenge. The purpose of this report is to review the natural history, clinical evaluation, and treatment of carcinoma of the nasopharynx.

Carcinoma↗
PubMed1991

Treatment options in spasmodic dysphonia.

Options in the treatment of spasmodic dysphonia include surgical interruption of the recurrent laryngeal nerve, anterior laryngoplasty, voice therapy, and Botulinum toxin injection. Although none of these treatments is ideal, Botulinum toxin injection appears to have the greatest potential to benefit the greatest number of patients.

Diagnosis, Differential↗
PubMed1991

Pediatric sinusitis: diagnosis and management with endoscopic techniques.

Sinusitis in children has recently received more attention as a possible etiology in chronic or persistent cough, chronic nasal congestion, purulent rhinorrhea, and generalized malaise. Its association with upper respiratory infections and allergy is still sometimes overlooked, however, resulting in prolonged but often inadequate treatment for the young patient. An attempt to better define the anatomy and physiology of the paranasal sinuses, along with a discussion of etiologies and diagnostic and therapeutic techniques, will provide some useful information in the management of this problem.

Bacterial Infections↗
PubMed1991

Evidence for the ventral origin of oligodendrocyte precursors in the rat spinal cord.

The neuroepithelial cells of the mammalian neural tube are thought to give rise to all classes of differentiated neurons and macroglial cells in the adult CNS. In most cases, the regulation and timing of commitment of neuroepithelial cells to specific differentiative pathways are unknown. It has been proposed that in developing spinal cord, the macroglial cells--astrocytes and oligodendrocytes--arise either by the direct transformation of radial glial cells in the developing cord or, alternatively, by the differentiation of distinct precursor cells which migrate to presumptive white matter from the region of the central canal during development. In this study, the timing of oligodendrocyte differentiation in different levels of the spinal cord and the capacity of specific regions of the spinal cord to give rise to oligodendrocytes at various ages was tested in vitro. At embryonic day 14, all complete segments, as well as all ventral regions along the rostral-caudal axis of the spinal cord, have the capacity for oligodendrogenesis. By contrast, dorsal regions of the thoracic and lumbar spinal cord do not develop the capacity for oligodendrogenesis until later in development. The capacity of dorsal rat spinal cord to give rise to oligodendrocytes appears to be associated with the ventral-to-dorsal migration of oligodendrocyte precursors. These observations suggest that commitment to an oligodendrocyte differentiative pathway appears to occur in a distinct population of ventrally located glial precursors in the embryonic rat spinal cord.

Animals↗
PubMed1991

Flow cytometric study of oxidative burst activity in bovine neutrophils.

A flow cytometric procedure was evaluated to measure the oxidative burst activity (hydrogen peroxide formation) of bovine neutrophils. The method involves measuring the oxidation of intracellular dichlorofluorescein to fluorescent dichlorofluorescein (DCF). Phorbol myristate acetate (PMA) was used to perturb the neutrophil plasma membrane. The sources of variation introduced into the DCF assay were also examined. The sources of variation were attributable to the isolation of neutrophils from blood, variation between duplicate assays and duplicate flow cytometric determinations of oxidative product formation, variation in neutrophil oxidative product formation among cows, and the variation (over repeated daily and weekly neutrophil isolations) in neutrophil oxidative product formation. A final objective was to determine effects of dexamethasone on oxidative product formation, and whether differences existed between blood and mammary neutrophils in oxidative product formation. There was an increasing trend in the formation of DCF with increasing time of incubation and with increasing PMA concentration. Increasing the concentration of PMA decreased lag time and increased the rate of oxidative product formation. The increase in DCF formation was statistically significant up to a PMA concentration of 10 ng/ml. This concentration was considered optimal for bovine neutrophils.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Pharmacologic enhancement or suppression of phagocytosis by bovine neutrophils.

Sixty-three drugs, belonging to 10 chemical classes, were tested in vitro to determine effects on phagocytosis of 32P-labeled Staphylococcus aureus by neutrophils isolated from milk. Within each class, the number of antibiotics tested were: nonsteroidal anti-inflammatory drugs (NSAID; 8), peptolids (2), aminoglycosides (8), tetracyclines and fusidic acid (4), beta-lactam antibiotics (25), secretolytic agents (2), macrolides (5), polypeptides (2), and antibacterial quinolones (8). Percentage of phagocytosis was determined after incubating (2 hours at 37 C) 12.5 x 10(6) viable neutrophils, 200 x 10(6) 32P-labeled S aureus with antibiotics and 5% skimmed milk. Concentrations of antibiotics tested were 1,000, 500, and 10 micrograms/ml of incubation media. When compared with nonantibiotic controls at the highest drug concentration, the NSAID acetylsalicylic acid and centrophenoxine increased phagocytosis 23.2 and 8.8%, respectively, and benzydamine, indomethacin, phenylbutazone, ibuprofen, and acetominophen decreased phagocytosis 22.8, 14.2, 9.8, 27.0, and 18.2%, respectively. The peptolids novobiocin and pristinamycin decreased phagocytosis 24.5 and 22.0%, respectively. The aminoglycosides tobramycin, amikacin, and gentamicin decreased phagocytosis 21.1, 15.4, and 19.2%, respectively. For the tetracyclines and fusidic acid, minocycline and doxycycline decreased phagocytosis 39.8 and 54.2%, respectively. The beta-lactam antibiotics carfecillin, cephapirin sodium, and cephacetrile sodium decreased phagocytosis 11.2, 12.8, and 23.8%, respectively. The secretolytic agent, bromhexin, increased phagocytosis 10.8%. These data indicate that the potential for enhanced phagocytosis exists through use of some NSAID, and for depressed phagocytosis through use of aminoglycosides, peptolids, tetracyclines, and beta-lactams, as well as certain other NSAID.

Animals↗
PubMed1991

Penetrating wounds of the neck.

The management of penetrating wounds of the neck provides several decision-making steps that remain controversial. The two basic concepts of management include the idea that all wounds deep to the platysma should be explored and (the more conservative concept) that selective neck exploration should be based on a battery of tests to identify traumatic injuries. The areas of agreement within these two schools of thought include exploration of wounds with obvious injury, exploration of wounds in which patients cannot be stabilized satisfactorily for further testing, and the idea that all patients with wounds deep to the platysma should be admitted to the hospital. The remaining issues, including the need for angiography, barium swallow, or endoscopy, still are contested. Mandatory exploration of neck wounds became popular during World War II. The weapons used, the lack of accurate testing, and delays in treatment caused by transport problems played significant roles in the development of this policy. Proponents of mandatory exploration of neck wounds contend that delays in treatment result in increased mortality rates. Also delays caused by lengthy diagnostic testing have resulted in rapid exsanguination of patients who might otherwise have been surgically salvageable. These factors, along with the potential for undetected injuries and the associated complications (including false aneurysms and mediastinitis) favor mandatory exploration. Advocates of routine neck explorations also note the low morbidity rates associated with a neck exploration. Reported rates of negative exploration are high, however, approaching 45%, and mortality rates vary from 2% to 9%. Selective neck exploration has gained popularity in some centers because of the lower negative exploration rates associated with this treatment, while comparable mortality rates are achieved. May found a negative exploration rate of 12% in his series of selective neck explorations and a mortality rate of approximately 3%. Furthermore, Noyes found that the hospital stay for patients with selective observation management not requiring a neck exploration was 2.8 days, compared with 4.2 days for patients with mandatory but negative neck explorations. A summary of diagnostic techniques and their indications in selecting patients with penetrating neck wounds for surgery is presented in Table 5. It has become apparent that both selective and mandatory explorations of neck wounds play important roles in treatment.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1991

Use of flow cytometry for determination of differential leukocyte counts in bovine blood.

A flow cytometric method was developed to perform differential leukocyte counts on bovine blood. Blood specimens from 50 healthy Holstein cows were analyzed by use of a flow cytometer. The method entailed diluting blood with phosphate-buffered, hypotonic saline solution containing acridine orange, and performing a step-wise, 3-parameter analysis on the bases of cell size, cellular granularity, and granulocyte fluorescence. Initially, proportions of monocytes, granulocytes, and lymphocytes were determined by creating appropriate windows on dot plots of cell size (determined by forward light scatter) vs cellular granularity (determined by the logarithm of side light scatter). Eosinophils were resolved by analysis of granulocytes as dot plots of logarithms of green vs red fluorescence ascribed to acridine orange. Proportions of eosinophils and neutrophils were computed from data so generated. Microclumps of platelets spuriously affected counts of some granulocytes, particularly eosinophils. Differential leukocyte counts determined by flow cytometry generally compared favorably with those obtained by use of the conventional microscopic method, using Wright-stained blood films. Mean neutrophil and eosinophil counts determined by the 2 methods did not differ significantly, but lymphocyte counts determined by flow cytometry were significantly higher than those determined by microscopy (P less than 0.01). Correlation coefficients for counts of neutrophils, eosinophils, and lymphocytes determined by the 2 methods ranged from 0.519 to 0.833. Correlation between monocyte counts was low (r = 0.147), although mean monocyte counts determined by the 2 methods did not differ significantly.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Detection of hepatitis B virus DNA using the polymerase chain reaction technique.

The polymerase chain reaction (PCR) technique has been utilized for the detection of hepatitis B virus (HBV) DNA, and several factors related to the selection of primer pairs for the PCR amplification have been demonstrated. The sensitivity of the PCR assay was compared with that of slot-blot hybridization for detecting HBV-DNA. Analysis by the PCR technique with Southern blot hybridization provided a greater than 10(4)-fold increase in sensitivity over the slot-blot hybridization analysis. Also, a rapid and sensitive PCR method for the detection of serum HBV-DNA was developed: HBV-DNA is released from virions by incubating serum with NaOH followed by neutralization with HCl. HBV-DNA sequences are then detected by agarose gel electrophoresis and ethidium bromide staining after PCR amplification with successive sets of primer pairs. In testing serial samples from chimpanzees experimentally infected with HBV, HBV-DNA was detected 2-3 wk before the appearance of hepatitis surface antigen (HBsAg) and continued to be detectable for a short period after the production of antibody to HBsAg. Results from testing of human serum demonstrated that the majority of patients with HBsAg in serum had HBV-DNA as well and that some patients had HBV-DNA in serum in the absence of HBsAg.

DNA, Viral↗
PubMed1990

Neovascularization occurs in response to crush lesions of adult frog optic nerves.

The capacity of the adult frog optic nerve to regenerate following a crush lesion is well established and is in contrast to the lack of regeneration of mammalian optic nerves after similar lesions. One factor which may contribute to the enhanced regenerative capacity of amphibian optic nerves is the rapid removal of cellular debris from the nerve after injury. In this study the morphology of normal and crushed frog optic nerves has been compared. Although the intraorbital region of the normal adult frog optic nerve is avascular, new intraparenchymal blood vessels appear central to the crush site 24 h after the nerve lesion. The appearance of these blood vessels is coincident with the appearance of granulocytes and macrophages in the nerve. Successful regeneration of the adult frog optic nerve may depend on this neovascularization to facilitate the rapid removal of cellular debris and to supply regenerating axons with trophic substances.

Animals↗
PubMed1990

Organization of the X gene region of the hepatitis B virus genome.

In the hepatitis B virus (HBV) genome four long open reading frames (ORFs) have been found that encode the virus core, surface and polymerase proteins as well as a protein that appears to be involved in virus gene expression (X). However, all HBV genomes examined contain two addition ORFs designated ORF5 and ORF6. ORF5 is located on the same strand as the four known viral genes and is 70-100 codons in size. ORF6 is located on the DNA strand complementary to the one that encodes the other virus genes, and is approximately 210 codons in length. Both ORFs are located in the X gene region which corresponds to the 3' terminus of the linear RNA genome. Northern blot analysis identified an X region specific transcript of approximately 0.7 kb. Although this transcript may be the template for the translation of the X gene protein it may also be involved in the expression of the protein encoded by ORF5. The promoter for this transcript may consist, in part, of the 15 residue sequence GCYTGYYTTGCYCGC because this sequence is near the 5' end of the transcript, it is highly conserved among hepadnaviruses, and it contains sequences involved in RNA polymerase binding. Also, the nucleotides within this region of the hepadnavirus genome are capable of forming a stable (G = -18 kcal/mole) hairpin structure. Understanding the organization and gene expression of the X region may be crucial in expanding our knowledge on the biology of HBV.

Base Sequence↗
PubMed1990

Hepatitis B virus DNA detection and comparison with hepatitis B surface antigen.

Hepatitis B surface antigen (HBsAg) has been used for the detection of hepatitis B virus (HBV). Recently, HBV detection using the polymerase chain reaction (PCR) has been shown to be a direct measure of complete virions and to be potentially a very sensitive method. Therefore, we attempted to analyze the relationship between HBsAg detection and HBV DNA assay by PCR. We tested HBV DNA by a modification of the PCR technique in serial sera from five chimpanzees experimentally infected with HBV and 29 human sera. Our new method of PCR analysis is as sensitive as former methods but is more simple and rapid than existing procedures. In chimpanzee studies, HBV DNA was detected 2-3 weeks before the appearance of HBsAg, and continued to be detectable 2 weeks after the production of antibody to HBsAg. Also, 3 of 11 chronic hepatitis B patients who lost HBsAg were positive for HBV DNA in serum, while all of patients who recovered from acute viral infection were negative for HBV DNA in serum. These results indicate that HBV DNA detection by PCR analysis is the most sensitive method currently available to detect the presence of complete virions in serum.

Animals↗
PubMed1990

Maturation of astrocytes in vitro alters the extent and molecular basis of neurite outgrowth.

In the developing mammalian central nervous system astrocytes have been proposed as an important substrate for axon growth. In the adult central nervous system following injury, astrocytes are a major component of the gliotic response which has been proposed to block axon growth. Experimental transplantation studies using cultured astrocytes have suggested that immature but not mature cultured astrocytes have the capacity to support axon outgrowth when transplanted into the adult rodent CNS. These observations suggest that astrocyte maturation is accompanied by changes in the functional capacity of these cells to support axon outgrowth. To determine whether this functional change reflects an intrisic astrocyte property, the extent and molecular bases of neurite outgrowth from embryonic rat cortical and chick retinal neurons on cultures of purified immature and mature astrocytes have been compared in vitro. The rate and extent of neurite outgrowth from both neuronal populations are consistently greater over the surface of immature than over the surface of mature astrocytes. Furthermore, antibodies to NCAM and G4/L1 significantly reduce neurite outgrowth on immature but not mature astrocytes, while antibodies to the integrin B1 receptor reduced outgrowth on both immature and, to a lesser extent, mature astrocytes. These results suggest that in vitro mature astrocytes have a reduced capacity and different molecular bases for supporting neurite outgrowth compared to immature astrocytes and are consistent with the proposal that functional changes during astrocyte maturation may partially contribute to regulating axon growth in the mammalian CNS.

Animals↗
PubMed1990

Detection of hepatitis B virus DNA in serum by polymerase chain reaction. Application for clinical diagnosis.

Standard methods of virus DNA detection using the polymerase chain reaction can be time consuming and can involve multiple steps in which contamination with exogenous DNA can occur. Therefore, we developed a simplified method for detecting hepatitis B virus DNA in serum. The main advantages of this method are that it can be performed rapidly, consists of only several steps, and has a false positive rate of less than 0.1% in our laboratory. In testing serial samples from five chimpanzees experimentally infected with hepatitis B virus, we found that hepatitis B virus DNA was detected 2-3 weeks before the appearance of hepatitis B surface antigen, and it continued to be detectable 1-3 weeks after the production of antibody to hepatitis B surface antigen. In testing serum from 84 human patients, we found hepatitis B virus DNA in all patients who had hepatitis B surface antigen and hepatitis B e antigen in serum and in 64% of the patients with hepatitis B surface antigen with antibody to hepatitis B e antigen in serum. Also, 3 out of 11 patients who were chronic hepatitis B carriers and who subsequently lost hepatitis B surface antigen were found to test positive for hepatitis B virus in serum. In contrast, all patients who lost hepatitis B surface antigen after acute hepatitis B virus infection or those classified as having non-A, non-B hepatitis tested negative for hepatitis B virus DNA. Thus, the modified PCR technique is a sensitive and rapid method for detecting hepatitis B virus DNA-containing virions in serum.

Animals↗