The accuracy of low field strength (0.08 Tesla) magnetic resonance imaging (MRI) of bone marrow for the detection of acute leukaemia in adults has been assessed by comparison with bone marrow biopsy results. Spin lattice relaxation time (T1) measurements from patients were compared with those from 90 volunteers. Eighteen patients were studied at the time of diagnosis of leukaemia. Bone marrow T1 was prolonged in all cases. One of two patients with refractory anaemia with excess of blasts in transformation (RAEBt) had prolonged bone marrow T1, the other had normal T1. T1 at the time of diagnosis for patients with acute leukaemia or RAEBt correlated with the cellularity and blast cell count in the marrow. None of the 17 patients who were studied when in long-term remission of leukaemia had prolonged marrow T1. Serial studies were undertaken in five of the newly diagnosed patients. An increase in bone marrow T1 was observed in each of four patients studied seven days after the start of treatment, at a time when they showed a decrease in leukaemic cells on peripheral blood examination. T1 measurements made 3 weeks after the commencement of chemotherapy were similar to pretreatment values and did not reflect the reduction in leukaemic infiltration observed on bone marrow needle aspirate. The implications and possible explanations for these findings are discussed.

Acute Disease↗

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Diagnostic and therapeutic evaluation of bronchoscopy.

The diagnostic and therapeutic efficacy of bronchoscopy was determined in 85 children. The major indications were foreign body removal in younger patients and evaluation of tracheobronchial pathology in older children. Foreign body was commonly isolated in the toddlers and even in the elder age group (19%) as well as in those with suspected ingestion (44%). Groundnut was the predominant foreign body and right bronchus was the most frequent site. Tracheobronchitis (27%), bronchiectasis (13%) endobronchial tuberculosis (9.4%) and mucus plug (3%) were the other frequent findings. Bronchography was performed in 16 patients and it confirmed the diagnosis in 75% of the cases. Minor complications were encountered in 8% of patients. In the present study bronchoscopy yielded definite results in 83% and in many, including those with normal findings it guided further management.

Adolescent↗

PubMedDate not supplied

Maternal biosocial factors affecting low birth weight.

The causes of low birth weight (LBW) are multifactoral with genetic, placental, fetal and maternal factors interplaying with each other. To assess the influence of some of the maternal bio-social factors on the variance of birth weight, this study was undertaken. A total of 984 consecutive live births delivered at an urban hospital were analysed. The rate of LBW was 28.3% and preterms accounted for 3.2%. A strong correlation existed between birth weight and maternal height, weight, age, ANC visits and risk status at pregnancy. A short, malnourished, young, unregistered or primiparous mother was associated with a higher rate of LBW. On multiple regression analysis it was noted that maternal weight, parity and ANC visits independently affected the birthweight of the new born. Therefore emphasis needs to be given to maternal biosocial factors which are amenable to improvement to reduce the incidence of LBW. This can be done by selectively targeting interventions to improve nutrition, and curtailing parity and promoting contraception.

Adolescent↗

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Minor and trace sterols in marine invertebrates. 61. Isolation and structure elucidation of new A-nor sterols from the marine sponge Phakellia aruensis.

An examination of the Australian sponge Phakellia aruensis led to the isolation and identification of sterols with six different nuclei. Eight new sterols were isolated which included three delta 15-A-nor sterols, three delta 7-A-nor sterols, and two saturated A-nor sterols. Their structures were established through mass spectrometry and 1H-NMR spectral studies.

Animals↗

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The action spectra of cone photoreceptors in the turtle (Mauremys caspica) retina.

Cone photoreceptors in the turtle retina are involved in intricate neuronal interactions with other retinal neurons that modify the responses of the cones to photons absorbed in their outer segments. Therefore, the action spectra of cones strongly depend upon the conditions of measurements. This study describes an attempt to derive the action spectra of turtle cones which are the least distorted by neuronal interactions. To achieve this goal, the photoresponses of cones and horizontal cells were recorded from the turtle retina under different conditions of adaptation using different patterns of the stimulating test flashes. The sensitivity action spectra, derived from small-amplitude (<1 mV) photoresponses, were strongly affected by the recording conditions indicating the contributions of multiple neuronal inputs. Action spectra, constructed from large criterion photoresponses, were less distorted by neuronal interactions and better described the spectral properties of the "isolated" cones. The action spectra of the hyperpolarizing inputs to chromaticity-type horizontal cells were derived by stimulating these cells with mixtures of a saturating red light and a monochromatic light of different wavelength and intensity. The action spectra were constructed from the intensity of the addend component needed to "pull down" the depolarizing response to the red component by a fixed criterion. These spectra, measured in red/green and yellow/blue C-type horizontal cells, are suggested to best represent the "isolated" M-cones and S-cones, respectively.

Absorption↗

PubMedDate not supplied

Spectral properties of short-wavelength (blue) cones in the turtle retina.

Long- and medium-wavelength cones in the turtle retina participate in complex neural interactions. They are coupled via excitatory pathways to other cones and receive negative feedback inputs from luminosity-type horizontal cells. Little information has been collected on the S- (short-wavelength or blue) cones because they are scarce in the turtle retina and of smaller dimensions compared to the other cone types. In this paper, flash sensitivity action spectra and photoresponses of seven turtle S-cones were measured in the dark-adapted state and during chromatic background illuminations. The desensitizing action of monochromatic background lights was not uniform across the visible spectrum. A red background was most effective in desensitizing the S-cones to long-wavelength stimuli while a blue background light produced its strongest action on the photoresponses elicited by short-wavelength stimuli. The effects of chromatic adaptation on the S-cone action spectrum and on the kinetics of the small-amplitude photoresponses suggested that the S-cones in the turtle retina were involved in complex neural interactions. These included excitatory inputs probably originating in neighboring L-cones and inhibitory long-wavelength inputs probably mediated by L-type horizontal cells.

Absorption↗

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A comparison of the AAPM "Protocol for the determination of absorbed dose from high-energy photon and electron beams" with currently used protocols.

A comparison of the AAPM "Protocol for the determination of absorbed dose from high-energy photon and electron beams" (TG21) with currently used protocols for electron and photon dosimetry is presented. These protocols are the International Commission on Radiation Units and Measurements Report 21, "Radiation Dosimetry: Electrons with Initial Energies Between 1 and 50 MeV" (ICRU21), and the AAPM "Protocol for the Dosimetry of X- and Gamma Ray Beams with Maximum Energies Between 0.6 and 50 MeV" (SCRAD). Assuming a given radiation exposure and chamber parameters, doses to water at dmax for electron beams and at 5 g/cm2 for photon beams are calculated using the three protocols and then compared. The doses for photon beams calculated using the TG21 and SCRAD protocols are found to differ by 3% or less at energies below 10 MeV. The largest differences occur in photon doses at high energies where the dose calculated with the TG21 protocol is as much as 5.5% greater than that calculated with the SCRAD protocol for a typical thimble ionization chamber. For low electron beam energies, the doses calculated with the ICRU21 protocol are as much as 5% less than TG21 doses when using thimble chambers constructed of tissue-equivalent materials in a water phantom. If dosimetry measurements are performed in polystyrene, the dose calculated using TG21 may be greater than the ICRU21 dose, depending on chamber size and composition. An explanation for some of the differences between the protocols is presented emphasizing the dependence on chamber geometry, chamber composition, and phantom composition.

Electrons↗

PubMedDate not supplied

Calibration and use of the Wisconsin kVp test cassette.

The Ardran-Crooks kVp test cassette is widely used in diagnostic radiology to provide a rapid, simple, noninvasive measurement of x-ray tube potential. A modified version of this cassette called the Wisconsin kVp Test Cassette was introduced commercially in the U. S. in 1972. Since then, the method of calibration of these cassettes has changed significantly. Wisconsin kVp Test Cassettes calibrated by the manufacturer prior to August 1982 may yield underestimates of kVp measurements, particularly when using the 90-110 and 110-130 kVp regions with single-phase units. In August 1982 significant improvements in the calibration methods were implemented. The resultant change in calibration is demonstrated by data from the Centers for Radiological Physics. Present calibration methods are believed to be accurate within the greater of +/- 2 kVp or 2% of actual peak tube potential. Proper use of the cassette is necessary to achieve this level of accuracy.

Biophysical Phenomena↗

PubMedDate not supplied

The anti-cancer activity of tumour necrosis factor.

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Animals↗

PubMedDate not supplied

Clinical expression of myotonic dystrophy: the predictive role of DNA diagnosis.

Myotonic dystrophy (DM), the most common muscular dystrophy of adult life, presents with a variety of clinical and genetic challenges to all involved; patients, their families, and clinicians. The clinical picture is extremely variable and may range from mild adult onset myotonia to severe congenital hypotonia associated with respiratory distress. An infant born to a mother with DM had remarkable hypotonia, expressionless face, respiratory difficulties, and club feet. Direct molecular genetic testing of the newborn and the mother showed trinucleotide repeat expansion mutations. Genetic counseling issues as well as the value of prenatal diagnosis are presented.

Adult↗