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Biomedical subjects

J R Mernagh

Publications and source records attributed to J R Mernagh.

13 recordsLinked to original sources
PubMed2001

Use of heparin in the investigation of obscure gastrointestinal bleeding.

OBJECTIVE: To determine if the administration of heparin improves the predictive value of angiography in the investigation of obscure gastrointestinal (GI) bleeding. METHODS: 18 patients with a history of chronic GI bleeding were investigated with angiography. For 6 patients, the cause of GI bleeding was established with angiography; the 12 patients who had negative results were given heparin for 24 h and were reassessed with angiography. RESULTS: After heparin administration, the source of GI bleeding was determined with angiography for 6 of the remaining 12 patients. Thus, heparinization increased diagnostic yield from 33% (6 of 18) to 67% (12 of 18). No significant complications, such as uncontrolled GI bleeding, occurred. CONCLUSION: Heparinization improves the diagnostic yield of angiography when obscure GI bleeding is being investigated.

Angiography↗
PubMed2000

Antenatal and postnatal findings in encephalocraniocutaneous lipomatosis.

Encephalocraniocutaneous lipomatosis (ECCL) is a congenital neurocutaneous syndrome that comprises unilateral porencephalic cysts with cortical atrophy; ipsilateral hamartomas of scalp, eyelid, and outer part of the eye; lipomas of the central nervous system (CNS); cranial asymmetry; and characteristic cutaneous lesions. We report on the antenatal and postnatal sonographic and radiologic, and on the postnatal pathologic findings of an infant diagnosed with ECCL at birth. The antenatal sonogram at 28 weeks of gestation showed normal intracranial structures; the sonogram at 38 weeks of gestation showed asymmetry of the cerebral hemispheres and ventriculomegaly. Magnetic resonance imaging at age 6 weeks demonstrated a porencephalic cyst on the left, hemiatrophy of the left cerebrum with cortical dystrophy, and a lipoma in the middle cranial fossa. Histologic findings of the resected cutaneous lesion confirmed the presence of fibrolipoma hamartoma. This case offers a unique insight into the antenatal and postnatal development of the hamartoneoplastic lesions of ECCL, and it highlights the difficulties inherent in the antenatal sonographic diagnosis of hamartoneoplastic syndromes.

Brain Diseases↗
PubMed1999

Prenatal sonographic diagnosis of hypochondroplasia in a high-risk fetus.

Hypochondroplasia (HCH) is caused by mutations in the fibroblast growth factor receptor type 3 (FGFR 3). Prenatal diagnosis of HCH based exclusively on the sonographic measurements of the fetal skeleton is difficult and has not been reported. We describe a newborn infant with HCH who was born to a mother with achondroplasia (ACH) and a father with HCH. Serial sonographic measurements were recorded from 16 weeks of gestation. All measurements remained normal up to 22 weeks of gestation. At 25 weeks of gestation, the long bones began to appear shorter than expected for gestational age, while the head measurements (biparietal diameter and head circumference) remained normal. The measurements were sufficiently different to distinguish from findings in normal and achondroplastic fetuses. Our findings suggest that it is possible to distinguish the normal fetus from a fetus affected with HCH and to distinguish HCH and ACH from each other based on the sonographic measurements alone. To our knowledge, this is the first report of longitudinal sonographic measurements of HCH in the second and third trimesters.

Achondroplasia↗
PubMed1999

US assessment of the fetal head and neck: a state-of-the-art pictorial review.

When attention is paid to the details of normal and abnormal fetal head and neck anatomy, abnormalities that normally would be missed at prenatal ultrasonography can routinely be diagnosed. Five basic views are used to assess the fetal head and neck: a transverse view of the head in the plane of the cavum septum pellucidum and cerebellum, a sagittal and a coronal view of the face to visualize the nose and lips, a sagittal view of the cervical spine, and a transverse view of the orbits to measure the biorbital and interorbital distances. Thickened nuchal fold, a common sign of Down syndrome, can be assessed with transverse images of the head. Transverse views are also useful to demonstrate cystic hygroma, occipital meningocele, and encephalocele, all of which can be associated with other severe anomalies. Micrognathia, cleft lip and palate, and macroglossia, which are best depicted with sagittal and coronal views of the face, are also associated with other fetal abnormalities. Visualization of these entities should prompt further search and amniocentesis. Lymphangioma of the tongue appears similar to macroglossia but is an isolated anomaly. Transverse views through the orbits are helpful for demonstrating orbital teratoma, orbital encephalocele, and hypo- and hypertelorism (the latter two being associated with other abnormalities). Sagittal views of the neck can demonstrate cystic hygroma, teratoma, and an enlarged thyroid.

Congenital Abnormalities↗
PubMed1990

Improved clinical facility for in vivo nitrogen measurement.

The design and construction of a hospital clinical facility for in vivo prompt gamma neutron activation analysis for total body nitrogen (TBN) measurement is described. The use of 252Cf neutron sources gives a better signal-to-background ratio compared with 238Pu-Be sources of equal strength, thus yielding better reproducibility of measurements. By measuring the hydrogen and nitrogen signals separately using appropriate gating circuits, signal-to-background ratio is further improved. Measurements using a urea phantom (5.63 kg nitrogen as urea in 34.53 kg of water) show that 2 x 6 micrograms 252Cf sources gives a nitrogen signal-to-background ratio of 5.6 (compared with 3.4 in the case of a 2 x 10 Ci 238Pu-Be source) and a reproducibility for nitrogen signal of +/- 1.1% (CV) and for hydrogen signal (internal standard) of +/- 2.33% (CV). Approximately 30 minutes of patient's time is required for each TBN measurement with an estimated reproducibility of +/- 3.8% (CV). The radiation dose to the patient is about 0.2 mSv (effective dose equivalent; QF = 10) per 20 min measurement. A report for the clinician is produced within a few minutes after the measurement by a dedicated IBM-PC computer. The entire facility is clean, comfortable and the electronics and computer processing are simple and economical.

Body Composition↗
PubMed1979

In vivo measurements of body protein based on the determination of nitrogen by prompt gamma analysis.

Measurement of nitrogen in the human body gives a measure of total protein in the body. Nitrogen (N) may be measured in vivo by a nuclear technique in which the characteristic nitrogen gamma rays emitted after capture of neutrons are detected and counted. The accuracy (as determined by comparison of the measurement of nitrogen in a pig by nuclear and chemical methods) is better than 10%. The reproducibility is less than 6%. The radiation dose is about 5 millirads. This method had been used with 43 patients and 23 normal volunteers and the results are reported. The data are presented in the from of total N content, percentage N by weight, and as a comparison of N and potassium (K) in the body. It is found that the mean percentage of N in the normal males is 2.5%, giving a value of 1.75 kg in the 70-kg standard man. The mean percentage values are not greatly different between normal volunteers and malnourished patients. Taking all subjects, N/K ratios ranged from 7.5 to 20 g/g. Thus K cannot be used as a predictor of N. Nitrogen content of normals correlates well (r = 0.68) with height squared; for malnourished patients there is again a good correlation (r = 0.81) but the regression line for patients is approximately 34% below that for the volunteers consistent with their depleted state.

Animals↗
PubMed1977

In vivo determination of nitrogen using Pu-Be sources.

A mehtod of measuring body nitrogen by neutron capture gamma analysis is described. The neutron flux is provided by four collimated 5 Ci Pu-Be sources, placed to give a bilateral irradiation of the subject. The 10-83 MeV thermal neutron capture gamma rays from 14N are detected by two heavily shielded 5 in X 4 in NaI(Tl) detectors. Results indicate a reproducibility +/-3% (1 SD) for a 10 min irradiation of the chest area, while giving a radiation dose equivalent of 50 mREM.

Activation Analysis↗
PubMedDate not supplied

Recent developments in in vivo neutron activation analysis facilities.

Two new facilities for in vivo activation analysis of patients have been designed, developed, and constructed at Toronto General Hospital. One of these is for the determination of body calcium for the diagnosis of osteoporosis and other diseases associated with bone loss. The other is for the measurement of total body nitrogen for the determination of protein status. These facilities replace old university facilities and take into account the comfort and management of patients. In addition, in the case of the calcium facility, the precision of the measurements has been improved because of larger detector volume and increased neutron source strength. Both the facilities are now in routine hospital clinical use.

Bone Density↗
PubMedDate not supplied

MR imaging of anorectal Crohn disease: a pictorial essay.

Magnetic resonance (MR) imaging has proved useful in the evaluation of perianal and perirectal lesions resulting from Crohn disease. On T1-weighted MR images, sinus tracts and fistulas are hypointense due to their fluid content; on T2-weighted images, their signal intensity depends on their fluid content and the degree of surrounding fibrosis. Other pathologic entities, such as abscesses in the ischioanal fossa, may become evident at MR imaging even though they remain hidden at digital examination. Rectal wall thickening and perirectal inflammatory changes are often seen at MR imaging of the pelvis. The multiplanar capability of MR imaging greatly facilitates the detection of fistulous tracts that extend into the supralevator space. MR imaging can be helpful to both the surgeon and the gastroenterologist in the assessment of perianal and perirectal complications arising from Crohn disease and, when necessary, in the planning of surgical intervention. MR imaging also recommends itself to the patient because it is noninvasive and does not cause discomfort.

Anal Canal↗
PubMedDate not supplied

Changes in body protein, body potassium, and lean body mass during total parenteral nutrition.

Lean body mass by anthropometry (AMLBM), total body potassium (TBK), and total body nitrogen (TBN) by prompt gamma analysis, are reported in 38 malnourished patients during total parenteral nutrition. Over long periods (greater than 2 months) TBN increased 32% while AMLBM and TBK rose only by 9.2 and 9.5%, respectively. Changes in AMLBM and in K were significantly correlated, but changes in nitrogen were not correlated with either. From short-term studies, the same conclusions can be obtained; although there are changes in lean body mass and in potassium, there is no correlation with such changes in nitrogen. With repletion, changes in body protein are not necessarily related to changes in AMLBM or to TBK: the latter two reflecting total and intracellular water, respectively, but not protein content.

Anthropometry↗