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A case of Ivemark's renal-hepatic dysplasia syndrome is presented. The findings are suggestive of a ductal obstructive process anatomically located at the junction of ducts with the parenchyma. The differential diagnosis includes Meckel syndrome, short rib polydactyly syndromes, and glutaric aciduria type 2. The molecular basis for this syndrome remains unknown.
To identify the most important determinants of the optimal timing for the initiation of antenatal fetal testing in a high-risk pregnancy (such as insulin-dependent diabetes mellitus), we performed a decision analysis based on a Markov model. The model incorporated several components: test sensitivity and specificity and week-specific probability estimates for fetal death, delivery, and neonatal morbidity and mortality. The analysis demonstrated that the optimal time in gestation to begin testing (from the combined standpoint of both maximizing neonatal survival and minimizing fetal death) was highly dependent on test specificity, the cumulative risk of fetal death (and its distribution throughout gestation), and the week-specific probabilities of neonatal death. For example, even with the increased risk of fetal death associated with insulin-dependent diabetes, very high test specificity (> 99%) is required to recommend testing before 30 weeks. If tests of lower specificity (higher false-positive rates) are used, neonatal deaths will increase and will not be offset by a corresponding decrease in fetal deaths. By performing sensitivity analyses, we demonstrated the effect and relative importance of the model components for determining the optimal gestational age to initiate fetal testing.
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This paper addresses the need to make evaluation part of the nurse's expanded role within the Primary Health Care system. In a social policy and decision-making context, the nurse is an intermediary between political authorities and community groups. This requires diverse, but complementary, evaluation skills. The author proposes a dual method of evaluation for community health programs. The approach incorporates an objective-stance Logical Framework Analysis Model, to meet agencies' needs for program effectiveness and impact data, and a Participatory Evaluation approach, to recognize the ability of communities to judge whether health services are responsive to their needs. The nature and application of both methods within an International Primary Health Care context are explored. The paper concludes that access to a wide spectrum of evaluation data places the nursing profession in a challenging position to influence policy decisions related to health services.
The ability of bone to adapt to its mechanical environment is well recognized, although the specific mechanical parameters initiating or maintaining the adaptive responses have yet to be identified. Recently introduced mathematical models offer the potential to aid in the identification of such parameters, although these models have not been well validated experimentally or clinically. We formulated a complementary experimental/analytic approach, using an animal model with a well-controlled mechanical environment combined with finite element modeling (FEM). We selected the functionally isolated turkey ulna, since the loading could be completely characterized and the periosteal adaptive responses subsequently monitored and quantified after four and eight weeks of loading. Known loads input into a three-dimensional, linearly elastic FEM of the ulna then permitted full-field mechanical characterization of the ulna. The FEM was validated against a normal strain-gaged turkey ulna, loaded in vivo in an identical fashion to the experimental ulnae. Twenty-four candidate mechanical parameters were then compared to the quantified adaptive responses, using statistical techniques. The data supported strain energy density, longitudinal shear stress, and tensile principal stress/strain as the mechanical parameters most likely related to the initiation of the remodeling response. Model predictions can now suggest new experiments, against which the predictions can be supported or falsified.
An analysis of a series of data providing a comprehensive impression of the effect of radiation on the induction of translocations in the spermatogonia of the mouse is presented. It is assumed that the spermatogonial stem-cell population is made up of a sensitive and resistant compartment, that the same type of basic lesion can lead to either translocation induction or cell inactivation, and that the basic lesion has a linear-quadratic dose relationship. The same set of parameter values is used to provide a quantitative description of the acute dose--response relationship and the effects of dose-rate and short-term, 24-h and long-term fractionation. The unusual effect of 24-h fractionation can be explained by proposing that the first dose blocks the progression of sensitive cells into the resistant compartment whilst the progression of the resistant cells into the sensitive compartment is unaffected. The analysis indicates that (1) the majority of the spermatogonial stem cells in the mouse are in the sensitive compartment; (2) that the yield of translocations is proportional to accumulated dose for chronic radiation schedules; (3) the biology of spermatogenesis should be taken into account when extrapolations are made from one animal species to another.
Aberrant transients in the cortical electroencephalogram of rats of the epileptic WAG/Rij strain were studied by means of spectral analysis. The EEG of rats of this strain contains, besides normal sleep spindles, high-voltage spiky phenomena, epileptic spike-wave discharges, and deviant intermediate stage. Spectral analysis of these transient phenomena shows that some features, like their peak frequency, are alike, but that they differ in other spectral characteristics, as in the first harmonic of the peak frequency and in the domain of the high frequencies. The results provide arguments for the view that spike-wave discharges might be considered as unique aberrant phenomena, presumably related but dissimilar to the high-voltage spiky phenomena and intermediate stage. Next to this, spectral analysis was used to study the intraphenomenal dynamics of spike-wave discharges. The peak frequency was found to decrease monotonously from about 10 Hz at the beginning of the spike-wave discharge to about 8 Hz at the end. Other spike-wave discharge frequency bands showed an intraphenomenal increase followed by a decrease. These time-variant EEG dynamics in spike-wave discharges might correlate with the cognitive disturbances during absence seizures in man.
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Despite agreement that chronic schizophrenia is clinically heterogeneous, no system of subclassification has received general acceptance. Most methods for defining subgroups have relied either on course or symptom type alone. Using cluster analysis on patients rated on a broad range of items derived from commonly employed explicit diagnostic criteria, we were able to define two reasonably distinct groups. The first and larger group was characterized by later onset, good premorbid adjustment, and well-organized delusions; the second by poor premorbid adjustment, early onset, family history of schizophrenia, and symptoms such as bizarre behavior, incoherent speech, and blunted effect. Two different clustering programs yielded similar profiles. Analysis of computer-simulated data indicated that such good agreement would occur by chance less than one time in a hundred. Furthermore, the groupings remained stable when extra cases were added to the sample, and affected family members showed a significant tendency to occur in the same cluster. Although an etiological distinction between the subtypes cannot be inferred, we suggest that this form of classification provides a potentially useful starting point for further biological and genetic research.
We report on the cluster analysis of 416 subjects from Montgomery County, Maryland, USA, who responded to lay interviewers using a telephone version of the Seasonal Pattern Assessment Questionnaire (SPAQ). Eight clusters are described, the smallest of which is consistent with a pattern comparable to that seen in patients with winter seasonal affective disorder (SAD). A larger group of individuals seems to demonstrate patterns equivalent to that of subsyndromal winter SAD patients. Furthermore, it was apparent that a large percentage of the study group seems to be affected to some degree by the characteristics of the seasons. It was observed, perhaps for the first time, that feeling worse when there is a high pollen count appears to be associated with the symptom pattern seen in winter SAD patients. There is also evidence for the existence of a group of summer subsyndromal SAD subjects.
In a mailed survey conducted at four centers--Nashua, NH; New York, NY; Washington, DC; and Sarasota, FL--1,671 respondents provided information on monthly variations in 10 behavioral categories representing extremes in the areas of mood, socializing, appetite, weight gain/loss, and sleep length. A 10-factor solution revealed the following factors: (1) a winter weight gain factor; (2) a winter depression factor; (3) a winter hypersomnia factor; (4) a summer weight gain factor; (5) a summer hypersomnia factor; (6) a summer depression factor; (7) a winter socializing factor; (8) a winter weight loss factor; (9) a fall depression factor; and (10) a possibly mixed factor. Factors consistent with winter seasonal affective disorder were positively correlated with latitude, while those consistent with summer seasonal affective disorder were negatively correlated with latitude.
Decision analysis was used to evaluate the results of treatment of T2N0M0 glottic carcinoma as presented in the literature. Based on mean values for recurrence, salvage eligibility after recurrence and salvage success, the 5-year survival after radiotherapy and surgery proved to be almost identical, 85 and 86%. If the recurrence rates and the salvage rates were varied, a marginal advantage for surgery in small tumours (T2a) and a major advantage in more extended (T2b) tumours was seen if only survival is considered. To take the quality of speech into account, a utility analysis was performed. A utility scale was defined ranging from 0.0 as the value for death, to 1.0 for a successfully irradiated patient with preservation of normal speech. A utility of 0.99 or less for the laryngectomized patient would favour radiotherapy over surgery for all T2 tumours. In patients with T2b tumours and in extreme circumstances, e.g. if failure rates of radiotherapy are extremely high or if recurrence rates after surgery are extremely low, an exact assessment of patient utilities may be pivotal. Under normal circumstances radiotherapy is preferred for T2N0M0 glottic carcinoma if both survival and the quality of speech are taken into account.
We model the non-local mechanisms of genomic evolution and propose methods for studying the evolutionary divergence of species based on these models. Mechanisms include the movement of segments of genomes within a single chromosome (transpositions), the reciprocal translocation of segments between two chromosomes, and the inversion of segments. Each of these is studied in the context of a different type of genomic data. We introduce the theory of phylogenetic invariants for evolutionary inference based on very long macromolecular sequences.
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The introduction of an attenuating medium into a photon beam serves both to reduce the intensity of the primary beam and to create secondary radiation due to scatter. When retracted missing tissue compensators are employed to compensate for irregular surface contour or internal inhomogeneities, they are often fabricated without regard to the scattered radiation that they introduce into the system. The study of a mathematically describable conical geometry has clearly demonstrated the need for improved compensator design. Experimental results obtained with this geometry can be reproduced with good agreement, using theoretical calculations based on primary and first order scattered radiation. This method of analysis may be extended to predict the shape of a compensator which will produce an optimized dose distribution at a given depth in a phantom, equivalent to that which would be obtained when an irregular surface is filled with unit density material (bolus), producing a flat surface. An optimized compensator was constructed based on these theoretical considerations and excellent agreement was observed between theory and experiment. Dramatic improvement in the restoration of bolus dose is obtained with this optimized compensator. Finally, an anthropomorphic phantom of the neck region has been constructed and the performance of a compensator designed according to current clinical methods for this geometry has been evaluated. The performance of an optimized compensator specific to this geometry is presented and good agreement between theoretical predictions and experimental results is observed. Dramatic improvement in bolus dose restoration over that obtained with the clinically designed compensator is realized.
The diagnostic utility of functional analyses has been demonstrated with a variety of behaviors including tics. Whereas previous analyses have focused on the discovery of maintaining variables to aid in treatment prescription, we employed a functional analysis to confirm a clinical diagnosis. An 11 year old male student, who had not been previously diagnosed with a tic disorder, exhibited multiple vocal tic-like behaviors which had persisted over a period of time. Teacher reports conflicted regarding the possible etiology of these behaviors. Hence, a functional analysis was conducted in the classroom to determine if the behaviors were maintained by operant variables. Our hypothesis stated that the occurrence of vocal behaviors across experimental conditions would strongly indicate the presence of a tic disorder. The functional analysis included the following conditions: attention, escape, alone, freeplay, and high sensory stimulation. We used a multi-element design to evaluate the effects of the different stimulus conditions on vocal-behavior frequency. Data indicated the student exhibited vocal behaviors in all conditions. However, the behaviors were partially exacerbated in the attention and escape conditions. Results supported the diagnosis of a transient tic disorder affected by operant variables.