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Biomedical subjects

J M Miller

Publications and source records attributed to J M Miller.

At least 325 records · Page 18Linked to original sources
PubMed1993

Molecular technology for hospital epidemiology.

Hospital-acquired infections in the United States contribute to approximately 80,000 deaths per year, with an associated cost of > $4 billion. Some of these infections are associated with outbreaks and clusters occurring within the hospital. The hospital infection control team must respond quickly and decisively to recognize and curtail these outbreaks, but their response often depends on critical laboratory data that characterize or "fingerprint" suspected microbial isolates. This presentation summarizes the simple, easily performed tests and the more molecular approaches that a hospital laboratory may take in support of infection control efforts. In addition to phenotypic data, such as biotype and antibiograms, hospitals that elect to incorporate molecular protocols should limit their first experiences to plasmid analysis and plasmid restriction endonuclease profiles.

Cross Infection↗
PubMed1993

Polymorphic ventricular tachycardia induced by programmed stimulation: response to procainamide.

OBJECTIVES: This study was designed to evaluate the effects of procainamide on polymorphic ventricular tachycardia induced by programmed stimulation and to correlate the responses with heart disease, left ventricular endocardial activation abnormalities and the signal-averaged electrocardiogram (ECG). BACKGROUND: Polymorphic ventricular tachycardia is induced frequently during electrophysiologic studies. In many patients this response is an artifact of programmed stimulation; in others, it appears to be clinically relevant. Previous observations have suggested that in some patients type IA antiarrhythmic agents can change the response to programmed stimulation from polymorphic to uniform ventricular tachycardia. METHODS: Programmed right ventricular stimulation was performed in the absence of antiarrhythmic drugs and after procainamide. Signal-averaged ECGs and left ventricular maps were performed during sinus rhythm in the absence of antiarrhythmic drugs. RESULTS: We evaluated 79 consecutive patients undergoing clinical electrophysiologic studies, in whom polymorphic ventricular tachycardia was the only arrhythmia induced in the absence of antiarrhythmic drugs. After procainamide administration, uniform monomorphic ventricular tachycardia was induced in 24 patients (Group 1), inducible polymorphic ventricular tachycardia persisted in 30 patients (Group 2) and no ventricular tachycardia could be induced in the remaining 25 patients (Group 3). Twenty-three (96%) of 24 patients developing uniform ventricular tachycardia after procainamide administration had coronary artery disease compared with 63% of Group 2 and 48% of Group 3 patients (p = 0.003). Left ventricular aneurysms were also found more frequently (46%) in the patients developing uniform ventricular tachycardia after procainamide than in either Group 2 or Group 3 (13% and 0%, respectively, p < 0.008). Abnormalities of the signal-averaged ECG typically seen in patients with spontaneous reentrant sustained ventricular tachycardia were significantly more frequent in patients who developed inducible uniform ventricular tachycardia after procainamide than in those who did not. Similarly, patients developing uniform ventricular tachycardia after procainamide had more extensive abnormalities of left ventricular endocardial activation revealed by catheter maps during sinus rhythm. CONCLUSIONS: The conversion of inducible polymorphic ventricular tachycardia to uniform ventricular tachycardia after procainamide administration occurs almost exclusively in patients with coronary disease, previous myocardial infarction and abnormal left ventricular function. This response may permit activation mapping of tachycardias, allowing the application of surgical or catheter ablation techniques that would otherwise not be possible in such patients.

Cardiac Pacing, Artificial↗
PubMed1993

Effect of transposition surgery on rectus muscle paths by magnetic resonance imaging.

PURPOSE: To evaluate effects of transposition on extraocular rectus muscle paths in middle and deep orbit. METHODS: The effect of various transposition procedures was assessed in five patients, using surface coil magnetic resonance imaging (MRI), performed with controlled gaze before and after surgery. Path changes were compared with those expected under conventional concepts of functional orbital anatomy, quantified by biomechanical modeling. RESULTS: Vertical rectus transpositions of 6 to 10 mm produced changes in muscle paths of 3 mm or less, assessed posterior to the equator of the globe. Lateral rectus transpositions as large as 10 mm resulted in almost no movement of muscle bellies. Conventional modeling predicted much larger changes. CONCLUSION: The authors observed less movement of rectus muscle bellies relative to orbital walls than would be expected under the traditional assumption that transposed muscles follow the shortest path from origin to insertion. This implies that middle and deep orbital tissues (connective tissues and compartmentalized orbital fat) constrain the paths of rectus muscle bellies, preventing them from sliding freely to follow their transposed insertions. The authors propose that these tissues function as "pulleys" elastically coupled to the orbital wall, and that they are important determinants of extraocular muscle function.

Adipose Tissue↗
PubMed1993

Atrioventricular nodal reentry: evidence supporting an intranodal location.

The exact site of the reentrant circuit in AV nodal reentry remains controversial. While recent ablative techniques have yielded information, the interpretation of which suggests that the atrium is required, other explanations for these interpretations are available. Prior pathophysiological studies with three-dimensional reconstruction of the node suggest that it is a highly anisotropic structure and extends through Koch's Triangle. Data from humans suggesting the atria are not necessary include the presence of AV dissociation during supraventricular tachycardia (SVT), depolarization of atrial tissue surrounding the node without affecting SVT, pacing induced AH intervals exceeding those during SVT, and site dependency of a critical AH interval (exceeding atrial refractoriness) that is required for initiation of AV nodal reentry.

Animals↗
PubMed1993

Parallel comparison of accuracy of API 20E, Vitek GNI, MicroScan Walk/Away Rapid ID, and Becton Dickinson Cobas Micro ID-E/NF for identification of members of the family Enterobacteriaceae and common gram-negative, non-glucose-fermenting bacilli.

We compared the API 20E (21 h) (API; bioMérieux Vitek, Hazelwood, Mo.), the Vitek GNI card (4 to 18 h) (Vitek; bioMérieux Vitek), the identification portion of the MicroScan Walk/Away Rapid Neg Combo 3 panel (2 h) (W/A; Baxter Diagnostics, Inc., West Sacramento, Calif.), and the Becton Dickinson Cobas Micro ID-E/NF rotor (21 h) (Cobas; Becton Dickinson Diagnostic Instrument Systems, Sparks, Md.), versus conventional biochemicals for their abilities to identify accurately 252 strains of biochemically typical and atypical members of the family Enterobacteriaceae and common non-glucose-fermenting gram-negative bacilli. All strains used were included in the data base of each product. At the end of the initial incubation, 194 (77.0%), 213 (84.5%), 198 (78.6%), and 192 (76.2%) strains were correct to the genus and species levels with the API, Vitek, W/A, and Cobas systems, respectively. After additional biochemical tests were performed, as directed by each manufacturer's protocol, the numbers of strains correctly identified to the genus and species levels were 241 (95.6%), 234 (92.8%), 243 (96.4%), and 230 (91.3%) with the four systems, respectively. The errors were random in all systems, with the exception of two atypical Salmonella enteritidis strains, each of which was misidentified by three systems. After the initial recommended incubation period, both API and Cobas were significantly less accurate than Vitek (Yates' corrected P < 0.05). No significant differences were noted between the results of Vitek and W/A or between the results of API and W/A. After additional tests were completed, Cobas was significantly less accurate than W/A (P < 0.05) but was equal in accuracy to Vitek and API. API, Vitek, and W/A were equal in accuracy after these same additional tests. All four systems were significantly more accurate after additional biochemical testing than after the initial reporting period (194 of 252 versus 241 of 252 for API, 213 of 252 versus 234 of 252 for Vitek, 198 of 252 versus 243 or 252 for W/A, and 192 of 252 versus 230 of 252 for Cobas [P<0.05]).

Bacteriological Techniques↗
PubMed1993

Evaluation of Biolog for identification of members of the family Micrococcaceae.

The Biolog Identification System (Biolog, Inc., Hayward, Calif.) was challenged at two separate laboratories with 113 coded isolates, including 33 type strains of staphylococci, 5 strains of Micrococcus spp., and 1 strain of Stomatococcus mucilaginosus. Test parameters between the sites were controlled as much as possible. Discrepancies were arbitrated by using conventional biochemicals. Overall accuracies (correct to the species level) upon initial testing were 47.7 and 59.3%, respectively, at the two laboratories. After repeat testing of isolates generating "no identification" responses or errors, the overall accuracies increased to 69.0 and 74.3% at the two sites, respectively, revealing no significant difference in the final results at the two laboratories (78 of 113 versus 84 of 113; P > 0.05). Error rates were 7.1% at one site and 9.7% at the other. The Biolog is not yet accurate enough to serve as a primary method for identifying staphylococci.

Bacteriological Techniques↗
PubMed1993

Numerical approach to reference identification of Staphylococcus, Stomatococcus, and Micrococcus spp.

A numerical-code system for the reference identification of Staphylococcus species, Stomatococcus mucilaginosus, and Micrococcus species was established by using a selected panel of conventional biochemicals. Results from 824 cultures (289 eye isolate cultures, 147 reference strains, and 388 known control strains) were used to generate a list of 354 identification code numbers. Each six-digit code number was based on results from 18 conventional biochemical reactions. Seven milliliters of purple agar base with 1% sterile carbohydrate solution added was poured into 60-mm-diameter agar plates. All biochemical tests were inoculated with 1 drop of a heavy broth suspension, incubated at 35 degrees C, and read daily for 3 days. All reactions were read and interpreted by the method of Kloos et al. (G. A. Hebert, C. G. Crowder, G. A. Hancock, W. R. Jarvis, and C. Thornsberry, J. Clin. Microbiol. 26:1939-1949, 1988; W. E. Kloos and D. W. Lambe, Jr., P. 222-237, in A. Balows, W. J. Hansler, Jr., K. L. Herrmann, H. D. Isenberg, and H. J. Shadomy, ed., Manual of Clinical Microbiology, 5th ed., 1991). This modified reference identification method was 96 to 98% accurate and could have value in reference and public health laboratory settings.

Bacterial Typing Techniques↗
PubMed1993

Collaborative evaluation of the Radiometer Sensititre AP80 for identification of gram-negative bacilli.

A multicenter trial of the Sensititre AP80 panel read on the Sensititre AutoReader (Radiometer America, Westlake, Ohio) for the automated identification of gram-negative bacilli was conducted with 1,023 clinical isolates (879 members of the family Enterobacteriaceae plus 144 nonenteric organisms). Assignment of taxa was based on the computer-assisted interpretation of the results of a series of reactions with fluorogenic enzyme substrates after 5 h of incubation, with an incubation interval of approximately 18 h used when indicated. Accuracy was determined initially by comparison with the results obtained with the API 20E or Rapid NFT system (Analytab Products, Plainview, N.Y.). Isolates showing discrepancies were identified by using conventional biochemical profiles. Identifications were available after 5 h of incubation for 918 isolates (90%). Agreements with reference results for members of the family Enterobacteriaceae were 95.3 and 92.5% at the genus and species levels, respectively, and for the nonmembers of the family Enterobacteriaceae, the agreements with reference results were 95.1 and 84.7%, respectively. The Sensititre AP80 panel was found to be simple and convenient to use, allowed for the testing of three isolates per panel, required minimal supplementary testing for completion of identification, performed in a reproducible fashion, and demonstrated an accuracy of same-day identification comparable to that reported for other automated systems. The AP80 panel appears well suited for routine use in the clinical microbiology laboratory as an automated means of identifying both members of the family Enterobacteriaceae and nonenteric gram-negative bacilli.

Bacterial Typing Techniques↗
PubMed1993

Effects of stellate ganglion stimulation on bilateral cochlear blood flow.

The effect of intraneural electrical stimulation of the stellate ganglion (SG) on bilateral cochlear blood flow (CBF) was investigated with laser-Doppler flowmetry. The SG of 15 anesthetized guinea pigs was exposed by a novel surgical approach and stimulated with a specially designed intraneural bipolar platinum-iridium electrode. Bilateral CBF was continuously monitored. Stimulation of 0.25 mA caused a detectable increase of the systemic blood pressure (BP) and a bilateral decrease of the cochlear vascular conductance (R, defined as the ratio CBF/BP). A stimulus of 0.5 mA elicited a statistically significant ipsilateral CBF (CBFi) decrease of 3.6% +/- 5.1% from the baseline and a contralateral CBF (CBFc) decrease of 3.1% +/- 5.5%. That no statistical difference was found between CBFi and CBFc indicates that a unilateral sympathetic stimulation of the SG can cause equal bilateral responses. These responses were accompanied by a significantly increased BP (8.7% +/- 5.2% of baseline) and consequently a greatly decreased R (12.2% +/- 6.5%) of the ipsilateral cochlea. Bilateral sections of the cervical sympathetic trunk below the level of the superior cervical ganglion did not alter the evoked changes in CBF, BP, and R. It is concluded that SG stimulation can decrease the conductivity of the cochlear vessels or the supplying vessels of the cochlea. Additionally, the SG nerve fibers that cause these effects do not pass through the superior cervical ganglion.

Animals↗
PubMed1993

Immunohistochemical detection of prion protein in sheep with scrapie.

Prion protein (PrP), which is involved in the pathogenesis of scrapie, occurs in 2 forms. The form extracted from scrapie brain is protease resistant (PrP-res), whereas PrP from normal brain is protease sensitive (PrP-sen). This study examined whether PrP-res could be detected in brains of sheep with scrapie by immunohistochemistry (IHC). A suitable IHC procedure was developed using brain tissue from hamsters that had been inoculated with the transmissible mink encephalopathy agent. Tissue samples were fixed in PLP (periodate, lysine, paraformaldehyde) that contained paraformaldehyde at a concentration of 0.125%. Before application of the IHC technique, tissue sections were deparaffinized and treated with formic acid to simultaneously enhance PrP-res immunoreactivity and degrade PrP-sen. Primary antibody was obtained from a rabbit immunized to PrP-res extracted from brains of mice with experimentally induced scrapie. Brain from 21 sheep with histopathologically confirmed scrapie were examined by IHC. In all 21 brains, PrP-res was widely distributed throughout the brain stem. Staining was particularly intense in neuronal cell bodies and around blood vessels. The IHC technique successfully detected PrP-res in brain samples that had been frozen or that were severely autolyzed before fixation in PLP. Brains from 11 scrapie-suspect sheep that were not considered histologically positive were also examined by IHC. PrP-res was found in 4 of these brains. Sections of brains from 14 clinically normal sheep did not have detectable PrP-res. Results of this study indicate that IHC detection of PrP-res is equivalent, and perhaps superior, to histopathology for the diagnosis of scrapie in sheep. Furthermore, IHC is applicable to tissues that have autolytic changes or processing artifacts that prevent satisfactory histopathologic evaluation for lesions of scrapie.

Animals↗
PubMed1993

Wegener's granulomatosis presenting as a primary seizure disorder with brain lesions demonstrated by magnetic resonance imaging.

Since the earliest attempt by Klinger in 1931 to describe the systemic vasculitis subsequently characterized in 1936 by Wegener as Wegener's granulomatosis, this disorder has been reported to present in a number of differing fashions. No previous description relates Wegener's presenting as a seizure disorder, and no reports of MRI of the brain in such patients exists. We relate such a case, along with MRI findings, prior to and after treatment, with a review of neurologic manifestations of the disorder.

Adult↗
PubMed1993

Effects of electrical stimulation of the superior cervical ganglion on cochlear blood flow in guinea pig.

It has been proposed that cochlear blood flow (CBF) is controlled in part by the sympathetic nervous system. In the present study the effect of electrical stimulation of the superior cervical ganglion (SCG) on CBF in guinea pigs was investigated using laser Doppler flowmetry (LDF). Animals were anesthetized with diazepam and fentanyl and the SCG was exposed. A custom-designed bipolar cuff electrode was fixed around the ganglion and 1 ms biphasic current pulses were injected at 0.15 mA to 1.5 mA, 6 Hz. Bilateral CBF was monitored, while the ganglion was stimulated for 3 or 5 min before and after the ascending sympathetic trunk and nerve branches from SCG were sectioned. Electrical stimulation of 0.5 mA caused the ipsilateral CBF (CBFi) to decrease 11.7% +/- 1.3 from the baseline (BL), while the contralateral CBF (CBFc) increased slightly due to the change in systemic blood pressure (BP). A linear relation was observed between the level of current stimulation and evoked reduction in CBF. Cervical sympathetic trunk section (between the SCG and the middle cervical ganglion) did not influence the pattern or the amplitude of CBF change in response to electrical stimulation of SCG. Sectioning the efferent fibers of the medial inferior and medial superior branch of the SCG only minimally reduced the amplitude of the CBF decrease evoked by electrical stimulation. However, sectioning the superior lateral branch abolished this decrease.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Provoked flux motion of cochlear blood flow measured with laser Doppler flowmetry in guinea pig.

Although progress has been made in the study of cochlear blood flow (CBF) regulation since laser Doppler flowmetry (LDF) was introduced, cochlear vasomotion has not been investigated. Therefore, the primary objective of this study was to determine if oscillatory fluctuations of CBF could be provoked. Guinea pigs were anesthetized with diazepam (5 mg/kg) and fentanyl (0.32 mg/kg). Blood pressure (BP) was recorded from a carotid artery cannula. The cochlea and pons cerebellum were ventrally exposed; the bilateral CBF and brain blood flow (BBF) or skin blood flow (SBF) were monitored by LDF. After administration of phentolamine (0.25-0.75 mg/kg, i.v.), ipsilateral CBF in 7 of 16 animals showed a 2-5 min episode of oscillation. During artificial hyperventilation, continuous oscillation of CBF was recorded (the flux motion frequency was 3.5 +/- 0.5 cycles per min and its amplitude 25.8 +/- 5.6% from baseline). The time-dependent flux change (the waveform) was the same throughout a single cochlea but different between cochleae of the same animal. Compared to BBF, CBF vasomotion frequency was lower, and amplitude larger. SBF exhibited no such motion. Flux motion could be eliminated by inhalation of pure oxygen or 5% CO2 in oxygen or by the smooth muscle relaxants, papaverine and hydralazine. Phentolamine-induced vasomotion may be due to a hypotensive perfusion pressure, and hyperventilation-enhanced vasomotion may be caused by changing blood gas concentrations and by hormonal or neuronal activity. Oxygen and CO2 inhalation slightly increased BP and this change in perfusion pressure was probably associated with weakened vasomotion.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Neurochemical and histologic characterization of striatal excitotoxic lesions produced by the mitochondrial toxin 3-nitropropionic acid.

An impairment of energy metabolism may underlie slow excitotoxic neuronal death in neurodegenerative diseases. We therefore examined the effects of intrastriatal, subacute systemic, or chronic systemic administration of the mitochondrial toxin 3-nitropropionic acid (3-NP) in rats. Following intrastriatal injection 3-NP produced dose-dependent striatal lesions. Neurochemical and histologic evaluation showed that markers of both spiny projection neurons (GABA, substance P, calbindin) and aspiny interneurons (somatostatin, neuropeptide Y, NADPH-diaphorase) were equally affected. Subacute systemic administration of 3-NP produced age-dependent bilateral striatal lesions with a similar neurochemical profile. However, in contrast to the intrastriatal injections, striatal dopaminergic afferent projections were spared. Both freeze-clamp measurements and chemical shift magnetic resonance spectroscopy showed that 3-NP impairs energy metabolism in the striatum in vivo. Microdialysis showed no increase in extracellular glutamate concentrations after systemic administration of 3-NP. The lesions produced by intrastriatal injection or systemic administration of 3-NP were blocked by prior decortication. However, the NMDA antagonist MK-801 did not block the effects of intrastriatal 3-NP, consistent with a non-NMDA excitotoxic mechanism. In contrast to subacute systemic administration of 3-NP, chronic (1 month) administration produced lesions confined to the striatum in which there was relative sparing of NADPH-diaphorase interneurons, consistent with an NMDA excitotoxic process. Chronic administration showed growth-related proliferative changes in dendrites of spiny neurons similar to changes in Huntington's disease (HD). These results are consistent with in vitro studies showing that mild metabolic compromise can selectively activate NMDA receptors while more severe compromise activates both NMDA and non-NMDA receptors. Chronic administration of 3-NP over 1 month produces selective striatal lesions that replicate many of the characteristic histologic and neurochemical features of HD.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1993

Vignette of medical history: Lazaretto Point.

During the Black Death's reign in the fifteenth century, a number of installations providing care for lepers were converted into quarantine stations. Known as lazarettos or pesthouses, they served as disinfection way stations for travelers and, later, as hospitals for those diagnosed with pestilential diseases (e.g., smallpox, typhus, cholera). Beginning in the late 1700s, quarantine stations and pesthouses were established in the Baltimore area, including Hawkins Point, Lazaretto Point, Fairfield, and Leading Point.

Baltimore↗
PubMed1993

Comparison of morbidity in cesarean section hysterectomy versus cesarean section tubal ligation.

This study was undertaken to compare the morbidity of cesarean section hysterectomy (C-HYST) and cesarean section bilateral tubal ligation (C-BTL) in a nonemergency or elective environment. Charts were reviewed for patients who underwent elective C-HYST or elective C-BTL before the onset of labor, without the use of antibiotics. Demographics, maternal morbidity, operative difficulties and postoperative complications were compared. Statistically significant differences in patient demographics include a higher maternal age in the C-HYST group than for those in the C-BTL group (31.0 +/- 5.8 versus 27.7 +/- 5.4 years; p = 0.002). C-BTL patients had higher gestational ages (39.4 +/- 1.6 versus 38.7 +/- 1.3 years; p = 0.0017). The C-HYST group had a higher estimated blood loss (1,201 +/- 472 versus 718 +/- 364 milliliters; p = 0.001), change in hematocrit level (6.0 +/- 4.4 percent versus 4.5 +/- 3.4 percent; p = 0.013) and operating time (115 +/- 37 versus 74 +/- 26 minutes; p = 0.0001). Blood transfusion was similar in both groups. Febrile morbidity was higher in the C-BTL group (68.0 percent versus 50.0 percent; p = 0.01). Endometritis was the significant determinant of febrile morbidity for the C-BTL group (41.7%) and cuff cellulitis in the C-HYST group (25.6 percent). Intraoperative and postoperative complications between the two groups were rare and not statistically different. Clinical morbidity for C-HYST is not significantly different than C-BTL. Elective C-HYST may be used in place of C-BTL when indications for hysterectomy are present.

Adult↗
PubMed1993

Vignette of medical history: porphyria in royalty.

The porphyrias are a group of uncommon inherited disorders caused by an accumulation of porphyrins in the body. This paper identifies many of the individuals in the royal houses of Stuart, Hanover, and Prussia who were afflicted with this condition, and highlights the impact this disease had on the history of England.

England↗