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Biomedical subjects

M H Reid

Publications and source records attributed to M H Reid.

At least 19 recordsLinked to original sources
PubMed1996

One-year follow-up evaluation of magnetic resonance imaging of the brain in dogs with pituitary-dependent hyperadrenocorticism.

OBJECTIVE: To evaluate magnetic resonance imaging (MRI) brain scans of dogs with pituitary-dependent hyperadrenocorticism (PDH) and no signs of CNS dysfunction 1 year after diagnosis and initial MRI. DESIGN: Prospective study of surviving dogs from a previous study. ANIMALS: 13 dogs underwent MRI of the brain at the time that PDH was diagnosed and prior to treatment. At that time, none of the dogs had clinical signs suggestive of an intracranial mass. Approximately 1 year after diagnosis and MRI, the brain was again evaluated by MRI. RESULTS: On the initial MRI scan, 5 of the 13 dogs had normal findings, and 8 had evidence of a mass (tumor) in the area of the pituitary gland. Of the 5 dogs that had no visible pituitary mass on the initial MRI scan, 3 had a normal MRI brain scan 1 year later. Of the 5 dogs that had no visible pituitary mass on initial MRI scan, 2 had a visible pituitary mass at 1 year. The 8 dogs that had a visible mass on the initial MRI brain scan had easily identified pituitary masses on the second MRI scan. Of these 8 dogs, 4 had no apparent change in pituitary mass size, and 4 had obvious increase in vertical height of the pituitary mass. Of the 4 dogs, 2 developed signs of neurologic dysfunction within 1 year after diagnosis of PDH, presumably attributable to that mass. Of the 13 dogs, 12 were treated with mitotane soon after completion of the initial MRI scan. Sensitivity to mitotane and initial pituitary mass size or growth were not correlated. Of the 13 dogs evaluated initially and 1 year after diagnosis, 10 had pituitary masses identified on MRI brain scans. CLINICAL IMPLICATIONS: The incidence of visible pituitary masses among dogs with PDH at the time of or within a year of diagnosis was > 75%. In 2 dogs, signs of CNS dysfunction developed within 1 year of PDH diagnosis when pituitary masses were > or = 10 mm.

Adrenocortical Hyperfunction↗
PubMed1995

Magnetic resonance imaging of the brain in dogs with recently diagnosed but untreated pituitary-dependent hyperadrenocorticism.

Magnetic resonance imaging was used to determine the prevalence of visible pituitary masses in 21 dogs with recently diagnosed and untreated pituitary-dependent hyperadrenocorticism. All dogs had clinical signs and routine database values (CBC, serum biochemical panel, and urinalysis) consistent with a diagnosis of hyperadrenocorticism, and none had clinical signs suggestive of an intracranial mass. Each dog had plasma cortisol concentrations after adrenocorticotropic hormone administration or low-dose dexamethasone administration consistent with hyperadrenocorticism. Pituitary-dependent hyperadrenocorticism was confirmed by the finding of 2 equal-size adrenal glands on abdominal ultrasonography and by results of plasma endogenous adrenocorticotropic hormone concentration and high-dose dexamethasone suppression testing. Sagittal and transverse T1-weighted magnetic resonance images of the brain were obtained before and after IV administration of gadopentenate dimeglumine. Eleven dogs had visible masses, ranging in size from 4 to 12 mm at greatest vertical height. Mean age and body weight of dogs with a visible pituitary mass was not significantly different from dogs without a visible mass. There was no significant difference in endocrine test results when comparing dogs with a visible pituitary mass to dogs without. The prevalence of visible pituitary masses in dogs with pituitary-dependent hyperadrenocorticism was greater than suggested by the prevalence of clinical neurologic signs.

Adrenal Cortex Diseases↗
PubMed1995

Magnetic resonance imaging for diagnosis of pituitary macrotumors in dogs.

The value of magnetic resonance imaging (MRI) for the evaluation of dogs with pituitary-dependent hyperadrenocorticism (PDH) and CNS signs was assessed. Magnetic resonance imaging of the brain was performed in 13 dogs with PDH and neurologic signs. The diagnosis of PDH was made on the basis of results of adrenocortical function tests and abdominal ultrasonography, in conjunction with appropriate history, clinical signs, and clinicopathologic alterations. Eight dogs had been treated with the adrenocorticolytic agent, mitotane, for 1 to 30 months before the development of neurologic signs. Prior to MRI, each dog had progressive neurologic signs that could not be attributed to hypocortisolism or mitotane toxicosis. The neurologic signs most frequently detected were disorientation and ataxia. Mean age of dogs at the time neurologic signs developed was 9.5 years. Sex predilection was not detected; however, most were large-breed dogs, with 11 of the 13 dogs weighing more than 20 kg. A large mass in the pituitary gland, suprasellar region, or both was easily identified on the magnetic resonance images of each dog. The masses ranged from 8 to 24 mm in size. Expansion of tumors into the suprasellar region and compression of structures adjacent to the pituitary gland were readily detected by MRI. Contrast enhancement did not improve tumor identification, but did enable better delineation between tumor and surrounding structures. After the diagnosis of a macrotumor was made by MRI, radiotherapy was initiated in 9 dogs and was successfully completed in 6. Three dogs had a relapse of neurologic signs 8, 11, and 26 months after radiotherapy was completed.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Epidemic aluminum intoxication in hemodialysis patients traced to use of an aluminum pump.

This study was designed to identify the source, risk factors, and clinical consequences of an outbreak of aluminum intoxication in hemodialysis patients using case-control and cohort studies. In 1991, a dialysis center in Pennsylvania [Dialysis Center A (DCA)] identified a number of patients with elevated serum aluminum levels. All patients receiving dialysis at DCA during January 1, 1987 to March 26, 1992 were involved in the study. A case-patient was defined as any patient with a serum aluminum level > or = 100 micrograms/liter after > or = 5 dialysis sessions at DCA. Fifty-nine case-patients were identified. Risk factors for elevated serum aluminum levels were receipt of bicarbonate- (rather than acetate-) based dialysate, higher number of sessions using bicarbonate dialysis, receipt of acid concentrate (used in bicarbonate dialysis) passed through one of two electric pumps, and a greater number of sessions using this concentrate. The electric pumps had an aluminum casing, casing cover, and impeller. Elevated levels of aluminum were found in acid concentrate after passing through a pump. Seizures and mental status changes requiring hospitalization were associated with aluminum exposure. We found that epidemic aluminum intoxication was caused by the use of an electric pump with aluminum housing to deliver acid concentrate used in bicarbonate dialysis. This outbreak demonstrates why it is essential to insure that all fluid pathways, storage tanks, central delivery systems, and pumps are compatible with low pH fluids before converting from acetate to bicarbonate dialysis.

Aluminum↗
PubMed1990

Epidemic hypotension in a dialysis center caused by sodium azide.

The water used for dialysate (dialysis fluid) in hemodialysis centers is produced by water treatment systems (WTS), which require careful and frequent monitoring. On November 3, 1988, nine patients receiving hemodialysis treatments at a single dialysis center suddenly developed hypotension within 30 minutes of onset of dialysis. Eight patients exhibited symptoms and two experienced syncopal episodes; there were no deaths. The incidence of dialysis-associated hypotension occurring within 30 minutes after dialysis onset for these patients was significantly higher during outbreak treatments than during preoutbreak (September 1 through November 2, 1988) treatments, (9 of 9 vs. 0 of 238, P less than 0.00001, Fisher's t-test). Sodium azide, a potent hypotensive agent, was identified as the probable contaminant within the WTS of the dialysis center at the time of the outbreak because: 1) it was mixed with glycerine as the preservative solution of each of the four ultrafilters that were put on-line in the WTS without rinsing, 12 hours before the outbreak; and 2) high levels of total organic carbons were detected from dialysis water collected at point-of-use sites at the time of the outbreak, suggesting contamination of the WTS with the sodium azide-glycerine preservative solution. To prevent similar occurrences, we recommend that ultrafilters (and other components of the WTS) be rinsed free of potentially toxic chemicals prior to use. Dialysis center personnel need to be aware of the potential affects that each modification of disinfection of the WTS may have upon the product water used to prepare dialysate for patient treatments.

Aged↗
PubMed1989

Design for an ultrasound-based instrument for measurement of tissue blood flow.

Quantitative measurement of tissue blood flow is of importance for many reasons: detection of capillary flow disturbances, evaluating indications for amputation, investigating vasospastic conditions, and evaluating vasoactive drugs or the effect of sympathectomy. Methods of investigating tissue blood flows include skin thermometry, thermal conductance or clearance, transcutaneous PO2, laser doppler flux, and photoplethysmographic techniques. A major reason that ultrasound has not previously been applied to this problem is that at the very low blood velocities in the capillaries (0.1 to 1 mm/sec) the Doppler shift is small (on the order of 1 Hz/MHz of carrier signal). Advantages of ultrasound are a noninvasive procedure and penetration depths greater than that possible with optical techniques. This paper discusses the development of a Doppler ultrasound instrument which allows spectral resolution of the velocities in tissue blood flow. Briefly, a low phase noise oscillator at 7.5 Mhz is used with two transducers to obtain the shifted signal. After mixing with the fundamental, the resulting low frequency signal is fed into a high resolution spectrum analyzer for analysis.

Biomedical Engineering↗
PubMed1984

Outpatient low-dose computed tomography metrizamide myelography and evaluation of lumbar disk disease.

Outpatient low-dose computed tomography metrizamide myelography (CTMM) for the evaluation of lumbar disk disease is described in 55 patients. Ten individuals (group 1) were studied using 3.5 ml of 150 mg I/ml (525 mg I total) of metrizamide. Forty-five additional patients (group 2) were examined with 5 ml of 110 mg I/ml (550 mg I total) concentration of metrizamide. Group 2 experienced less post-procedure headache (6.6%) and nausea (2.2%) than did group 1 (30% and 10%, respectively). Group 2 demonstrated a lowered rate of headache (p less than .01) and showed a trend to less nausea (p less than .09) than a recently published study describing full-dose lumbar myelography. In addition, CTMM in group 2 produced more uniform mixing of metrizamide than in group 1. Overall, low-dose CTMM increased accuracy and reduced morbidity, patient cost, and inconvenience as compared with routine full-dose lumbar myelography.

Adult↗
PubMed1984

Laryngeal carcinoma: high-resolution computed tomography and thick anatomic sections.

High-resolution 2-mm thick sequential CT scans of 23 patients with primary laryngeal carcinoma were reviewed to judge the value of CT in early tumor detection and the ability of CT to establish tumor extent reliably, particularly early cartilage invasion. False-negative results were likely when superficial lesions were confined to the true vocal cord mucosa. False-positive examinations occurred with vocal cord polyps and with acute and chronic granulomatous reaction of the vocal cords. In tumors large enough to be imaged, there were no false negatives. False-positive results for clearly identified tumors were related to the interpretation of tumor on CT where only edema was present at surgery. Both early and gross cartilage invasion were well correlated with surgically resected specimen sections. Early cartilage involvement by tumor can be detected by the development of a fenestrated chondral margin. Other benign expansive cartilage processes, such as occur with chondromas, have calcified cartilage fragment distributions that are out of proportion to any soft-tissue mass present.

Aged↗
PubMed1983

Organ and lesion volume measurements with computed tomography.

Useful clinical information will often result from determinations of organ and lesion tissue volumes from measurements of computed tomographic (CT) cross sections. This paper discusses simple applications of stereology to volume estimations of organs and disease processes. The method is applied to CT sections and, for equivalent accuracy, is less time consuming than planimeter or CT scanner region of interest outlining and measurements.

Adult↗
PubMed1983

The value of computed tomographic metrizamide myelography in the neuroradiological evaluation of the spine.

The diagnostic value of plain film metrizamide myelography (PFMM) was compared with computed tomographic metrizamide myelography (CTMM) in a study of 106 individuals who had undergone high-resolution computed tomographic scanning of the spine. CTMM provided more significant information than PFMM in 42 of 106 cases (40%), but showed no advantage over PFMM in 63 of 106 cases (59%). In 19 of the 42 cases (45%), PFMM was useful in directing the CT analysis to the appropriate region of pathology. In one patient, PFMM revealed a mobile herniated disc that had not been visualized with CTMM. In 30 of 106 cases in which plain CT scans of the spine were also obtained, the addition of intrathecal metrizamide demonstrated additional pathology in ten individuals. In general, CTMM was useful in the delineation of a variety of pathologic entities, especially neoplasms and congenital abnormalities. Low-dose CTMM (3 ml of a 150 ml/mg concentration) was performed as an outpatient procedure and found to be a useful adjunct to plain CT in two patients. A schema for the radiological evaluation of pathology of the spine is presented.

Adolescent↗
PubMed1983

Sonographic evaluation of hydatidiform mole and its look-alikes.

Seventeen proven cases of complete hydatidiform mole and 14 sonographically similar nonmolar cases were studied in detail with a variety of ultrasound transducers. Complete hydatidiform moles can be reliably differentiated from other lesions with similar sonographic appearances by using a highly focused ultrasound transducer to image the near field of the intrauterine contents.

Abortion, Incomplete↗
PubMed1982

Sonographic spectrum of retroplacental hemorrhage.

Retroplacental hemorrhage (RPH), or abruptio placentae, usually occurs in the third trimester of pregnancy and may or may not be clinically significant. Sonographic criteria necessary for diagnosis of RPH include visualization of a linear or biconcave, and usually well-marginated mixed echogenic or anechoic region posterior to the placenta. Large areas of hemorrhage may cause bulging of the chorionic plate while small areas may be difficult to discern with routine scanning. Secondary signs of RPH include associated intraplacental anechoic regions secondary to bleeding or infarction and visualization of intra-amniotic hemorrhage. In this report, nine cases of pathologically confirmed RPH are reviewed. Also reviewed are normal and other pathological conditions of the placenta which may mimic RPH but should not be confused with the sonographic diagnosis.

Abruptio Placentae↗
PubMed1981

Mammography- misunderstood and underutilized.

A mammography screening program for breast cancer carried out in Sacramento by the University of California Davis School of Medicine, Davis, was canceled because of negative public reaction to sensationalized reports in the lay press on the potential carcinogenic risks of the radiation exposure, along with passivity on the part of the medical community in defending the procedure and the program. Disappointment in this occurrence spurred us to explore physician's knowledge of and attitudes toward breast cancer and mammography. The results confirmed our suspicions that a significant number of physicians lack accurate knowledge of breast cancer and of the extremely high benefit-to-risk ratio of mammography as a means of early detection.

Attitude of Health Personnel↗