Biomedical subjects
Publications and source records attributed to J Watts.
A patient is described with recurrent cholangitis and longstanding alcoholic cirrhosis. The cause of the cholangitis was found to be intraductal biliary tract invasion by hepatocellular carcinoma. A review of the literature suggests that this is an unusual manifestation of a common malignancy.
Fifteen enterally fed preterm infants not receiving additional trace element supplements and 22 preterm infants receiving total or partial parenteral nutrition supplemented with zinc at 350 micrograms/kg/day and copper at 20 micrograms/kg/day were examined 1, 7, 14, 21, and 28 days after birth. Mean serum Zn concentrations in the parenteral group remained relatively constant and were significantly higher (P less than 0.01) at day 21 than the value for the enteral group. In contrast, a significant decline in mean serum Zn concentrations occurred between days 1 and 21 in the enteral group. The mean serum Cu concentrations in the parenteral group rose during the first week, and were significantly higher at days 14 and 21 than corresponding values in the enteral group. This trend did not result from copper supplementation alone but was also attributed to the presence of ceruloplasmin in blood transfusions. Mean serum Se concentrations did not change significantly, either between or within the two groups, except during the first week, at which time levels rose in the parenteral group. The addition of Zn, Cu, and probably of Se to parenteral infusates, allows the maintenance of appropriate serum values.
In magnetic resonance (MR) imaging manipulating spatial resolution, contrast resolution, and imaging time separately results in improvement in some parameters without degradation of others. The authors have found that MR imaging of the head with a repetition time TR = 2.0 seconds produces images with high signal-to-noise levels and excellent sensitivity to demyelinating disease and brain water content. In the body, a long TR yields large signal levels that permit delineation of low-intensity structures such as patent vessels and bone. The long TR technique can be used in a high-resolution mode (256 X 256 data acquisition elements, each 0.8 X 0.8 mm) while maintaining image times of 50 or 100 sec/section. For normal resolution (1.7 X 1.7 mm), imaging time is 25 or 50 sec/section. It is concluded that the combination of slow-imaging techniques with simultaneous multisection imaging will prove practical for clinical MR.
Magnetic resonance images of the head, abdomen, and pelvis of normal adult men were obtained using varying magnetic field strength, and measurements of T1 and T2 relaxations and of signal-to-noise (SN) ratios were determined. The T1 relaxation of gray matter, white matter, and muscle increases and T2 decreases with field strength, while T1 of fat remains relatively constant and T2 increases. As a consequence, for any one spin echo sequence, gray/white matter contrast decreases and muscle/fat contrast increases with field. SN levels rise rapidly up to 3.0 kgauss and then change more slowly, actually dropping for muscle. The optimum field for magnetic resonance imaging depends on tissue type, body part, and imaging sequence, so that it does not have a unique value. Magnetic resonance systems that operate in the 3.0-5.0 kgauss range achieve most or all of the gains that can be achieved by higher magnetic fields.
The authors describe a new method for magnetic resonance (MR) imaging of flowing protons which can illustrate relative blood velocity in the arteries supplying the brain. The magnetic gradient pulse sequence was synchronized to the cardiac cycle at 100-msec. increments to track pulsatile blood flow perpendicular to the image plane. The magnitude of the signal increased with the velocity of blood in major arteries flowing in the direction of the spatially offset refocusing plane. The blood velocity in the vertebral and internal carotid arteries varied as a function of the phase of the cardiac cycle, and the velocity profiles across the vascular lumina were compatible with laminar flow.
A prospective study of premature infants admitted to an intensive care neonatal unit was undertaken to evaluate the relative role of blood transfusions and maternal exposure in infections caused by cytomegalovirus (CMV), varicella zoster virus (VZV) and herpes simplex virus (HSV). During the first year of life, 13.7%, 4.8% and 4% of the infants became infected with CMV, VZV and HSV, respectively, as determined by virus isolation or seroconversion. Transfusion in the newborn period did not influence the rates of VZV or HSV infections. A higher rate of CMV infections occurred in transfused (18.8%) than in non-transfused (11%) infants but the difference was not statistically significant. A significant correlation was found between maternal antibody titers and the rate of CMV infection in infants whether or not transfusion occurred. An even stronger association was found between breast feeding and CMV infections. The risk of alloimmunization to erythrocyte and leucocyte antigens was also assessed; no evidence of increased alloimmunization to these antigens was associated with transfusion.
A study of 24 rats implanted in the hind leg with mammary adenocarcinomas and five sham-implanted rats, followed from the second to the eight week postimplantation, showed nuclear magnetic resonance imaging capable of detecting all the tumors without yielding any false-positives in the control rats. The T1 relaxation time of tumors overlapped that of muscle, and the T2 times overlapped fat, but the combination was unique when comparing tumors to muscle and fat. Necrotic regions of the tumor and the bladder contents tended to have very long T1 and T2 relaxation times. The difference in relaxation time between tumors and muscle could be accounted for in terms of water content, which was approximately 8% higher for the tumors. The study corroborates data from previous studies indicating that NMR imaging is a highly sensitive modality, although T1 and T2 times are not exclusive indicators of malignancy.
A double-blind randomly controlled trial of one particular laxative, Senokot, used in moderate dosage, was carried out on a group of 40 children with severe and persistent soiling and often with a history of faecal retention. Significant improvement occurred following three months of outpatient treatment using a behavioural approach and either Senokot, placebo or no medication. However, there was no evidence either during the trial or subsequently when Senokot was employed to supplement behavioural treatment in every child who continued with therapy that this laxative contributed in any way to relieving the problem in this group of cases.
Advances in imaging technique have improved the efficiency of clinical nuclear magnetic resonance (NMR) imaging, and will allow total patient examination time that equals or is more favorable than that of x-ray computed tomography (CT). The whole head can be examined with NMR in a 6.5-minute imaging time with a spatial resolution of 1.7 mm. Fifteen sections in the body can be similarly imaged. Quantitative T2 ("spin-spin" relaxation time) information, as well as estimates of T1 ("spin-lattice" relaxation time) can be obtained in this time. Quantitative T1 information requires an additional procedure.
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Nuclear magnetic resonance (NMR) images of live rats with sterile and pyogenic abscesses, hematomas, and various implanted and spontaneous neoplasms demonstrated good contrast differentiation between pathologic and surrounding normal tissues. This differentiation was maximal when both the T1 and T2 tissue relaxation times were used as criteria. Neoplasms have a broad range of T1 and T2 values and may be confused with abscesses or hematomas. Tissue rate constants (1/T1 and 1/T2) are mainly dependent on total water content, the exception being fat, which has a 1/T2 value much shorter than that expected on the basis of water content alone.
NMR imaging is based on the ability to induce and monitor resonance of the magnetic moment of nuclei with an odd number of protons and/or neutrons in the presence of magnetic fields. By the use of magnetic fields whose strength varies with position, it is possible to define both the location and concentration of resonant nuclei, and, thereby, to create images that reflect their distribution in tissue. Hydrogen because it is the most sensitive of the stable nuclei to NMR and because it is also the most abundant nucleus in the body, is ideally suited for NMR imaging.
Live rats were imaged by nuclear magnetic resonance (NMR). These images demonstrated fine detail and high object contrast. Motion artifacts are not apparent in 4-minute images, and major blood vessels are demonstrated as regions of low signal intensity because of blood flow. Selective contrast enhancement is possible by varying NMR imager accumulation parameters.
A nuclear magnetic resonance (NMR) imager with a 6.5-cm aperture is described. Spatial resolution is 0.47 X 2.0 mm with a slice thickness of 8.4 mm. Contrast resolution is 3% for a 4-minute image. Because of the excellent spatial resolution and high contrast between soft tissues, the images provide a great deal of detail and reconstruction artifacts due to motion are avoided. Blood flow can be observed, and selected enhancement of lesions thorough the modification of software-controlled operational parameters is demonstrated.
Spontaneous fatal aspergillosis occurred in several species of parrots imported from Latin America, Australia, Malaya and Ghana for studies on the control of psittacosis. Over a period of 4 years, 655 parrots were imported for use in these studies. All birds that died during these investigations were necropsied, and the internal organs of 45 were found to have macroscopic lesions suggestive of aspergillosis. Of these 45 suspected cases, 32 were confirmed as aspergillosis by both histopathology and culture, and three others by histopathology alone. There was no evidence that the remaining 10 had this disease. Of the 32 culturally confirmed cases, 13 were found to be caused by Aspergillus fumigatus, 16 by A. oryzae, and three by both fungi. In this series, three sets of circumstances appear to have been associated with the development of fatal aspergillosis. Their capture and transport to the United States, the administration of chlortetracycline used in the control of psittacosis, and the administration of cortisone acetate in an attempt to activate existent latent psittacosis infections. The possible causal relationship of these factors are discussed.