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M Knapp

Publications and source records attributed to M Knapp.

At least 181 records · Page 10Linked to original sources
PubMed1993

Mapping of the gene for X-chromosomal split-hand/split-foot anomaly to Xq26-q26.1.

A large inbred kindred from Pakistan in which an isolated type of split-hand/split-foot anomaly is transmitted as an X-chromosomal trait has previously been described. An X/autosomal translocation and an X-chromosomal rearrangement have been excluded by cytogenetic studies. In order to map the gene responsible for this disorder, linkage analysis has been performed by using 14 highly polymorphic DNA markers distributed over the whole X chromosome. Two-point linkage analysis between the disease locus and X-chromosomal marker loci gives maximal lod scores at theta = 0.00 with the loci DXS294 (Zmax = 5.13) and HPRT (Zmax = 4.43), respectively, suggesting that the gene for the X-chromosomal split-hand/split-foot anomaly is localized at Xq26-q26.1.

Chromosome Mapping↗
PubMed1993

The haplotype-relative-risk (HRR) method for analysis of association in nuclear families.

One major problem in studying an association between a marker locus and a disease is the selection of an appropriate group of controls. However, this problem of population stratification can be circumvented in a quite elegant manner by family-based methods. The haplotype-relative-risk (HRR) method, which samples nuclear families with a single affected child and uses the parental haplotypes not transmitted to that child as a control individual, represents such a method for estimating the relative risk of a marker phenotype. In the special case of a recessive disease, it was already known that the equivalence of the HRR method with the classical relative risk (RR) obtained from independent samples holds only if the probability theta of a recombination between marker and disease locus is zero. We extend this result to an arbitrary mode of inheritance. Furthermore, we compare the distribution of the estimators for HRR and RR and show that, in the case of a positive linkage disequilibrium between a marker and disease allele, the distribution of the estimator for HRR is (stochastically) smaller than that for RR, irrespective of the recombination fraction. The practical implication of this result is that, for the HRR method, there is no tendency to give unduly high risk estimators, even for theta > 0. Finally, we give an expression for the standard error of the estimator for HRR by taking into account the nonindependence of transmitted and nontransmitted parental marker alleles in the case of theta > 0.

Alleles↗
PubMed1991

Testing for association in SLE families.

Systemic lupus erythematosus (SLE) is a complex disease which is partly determined by genetic factors which influence susceptibility to the disease phenotype. In this association study we try to define the high risk haplotypes which are responsible for this disease, together with other environmental factors. In many other association studies a set of SLE patients is compared to a set of controls. The basic assumption about the underlying population is that the disease and control sample should originate from the same genetic population, which is not always completely satisfied in many studies. Therefore, we analyse our family data by applying the Haplotype Frequency Difference (HFD) Method, which constructs its internal control group from those haplotypes not transmitted to the affected individual. Results partially conform with other studies, showing that the haplotypes B8 DR3 as well as B7 DR2 have a high positive association with SLE. When the DR locus was analyzed alone, we found besides the alleles DR2 and DR3 a negative association for DR1, DR5, and DR6.

Adult↗
PubMed1991

Costs, needs, and outcomes.

There is a tendency in discussions of mental health policy and psychiatric practice to talk of the cost of a treatment, facility, or policy and to ignore variations. These variations can be considerable, which alone suggests they should not be overlooked, and they can be explored and perhaps exploited to improve the delivery of services. This article describes a theoretical framework for the examination of cost differences, applies it to a particularly rich data base on people with long-term mental health problems moving from hospital to the community, and uses the empirical evidence to address four key policy questions. The study finds encouragingly strong positive associations between costs, needs, and outcomes. It also uncovers significant cost-effectiveness differences between the public and private sectors and between community accommodation types.

Adult↗
PubMed1991

Ontogeny of the benzodiazepine receptor in human brain: fluorographic, immunochemical, and reversible binding studies.

The prenatal and postnatal human ontogeny of the central benzodiazepine receptor was investigated in six different brain regions between week 24 postconception and age 14 years. Binding studies, which were performed with [3H]flunitrazepam [( 3H]FNZ), revealed a steep increase in receptor density postnatally in frontal cortex and cerebellum. Bmax values were higher in medulla oblongata, pons, and thalamus than in cortex and cerebellum up to week 26. After that, receptor densities declined significantly in medulla and olive. The same tendency was apparent in pons, whereas receptor density remained unchanged in thalamus. The early ontogeny of the benzodiazepine receptor was also evaluated in fluorographs [( 3H]FNZ) and immunoblots using the alpha 1-subunit-specific monoclonal antibody (mAb) bd-24. Specific radiolabeled proteins with molecular weights of 53K and 59K were visible in cortical membranes from gestational week 8, the earliest time investigated. During further development, the intensity of the 53K band increased without changes in the 59K band. As in other species, postmortem proteolysis in human brain led to a specifically labeled peptide of 47K. The mAb bd-24 immunolabeled only the 53K protein and the 47K peptide.

Adolescent↗
PubMed1990

Diagnostic value of body plethysmographic parameters in healthy and asthmatic young children is not influenced by breathing frequency.

In 16 healthy and 16 asymptomatic asthmatic children (age range 5-8 yr; 8 girls, 24 boys) we studied the influence of breathing frequency on the results and the diagnostic value of body plethysmographic measurements. Airway resistance (Raw), specific airway resistance (SRaw), and thoracic gas volume (TGV) were measured during breathing (or breathing efforts against a closed shutter) at 0.4, 1, and 2 Hz. SRaw was computed by a simplified procedure directly from flow at the mouth vs. box volume-curves. The diagnostic value of each parameter was assessed as the percentage of correctly classified healthy and asthmatic subjects by means of discriminant analysis. When frequency was increased from 0.4 to 1 and 2 Hz mean TGV rose by 5 and 14% in healthy children and by 11 and 21% in asthmatic children, respectively. From 0.4 to 1 Hz mean Raw decreased by 16% (P = 0.002) in healthy children and by 25% (P = 0.0004) in asthmatic children. The differences in Raw between both groups decreased with frequency (3.5, 1.8, and 1.5 cm H2O.L-1.s at 0.4, 1, and 2 Hz, respectively) and those of TGV increased (0.13, 0.21, and 0.23 L). SRaw showed similar frequency characteristics as Raw. As intra-group variability changed in parallel with the differences the diagnostic value of the parameters remained constant with frequency. Simplified SRaw alone and TGV combined with Raw exhibited no differences in their diagnostic values (81-84% correctly classified).(ABSTRACT TRUNCATED AT 250 WORDS)

Airway Resistance↗
PubMed1990

Costing mental health services.

In this paper four principal topics are addressed: (a) the policy and political contexts in which demands arise for cost information; (b) the nature and phasing of those demands; (c) the basic rules of empirical costs research for meeting those demands; and (d) concomitant implications for the design, execution and interpretation of their research. Mental health care policy or practice changes which ignore costs, or which embody cost information without obeying or recognizing the four basic rules, can only be of dubious validity, or can only be used to answer a limited range of questions. But, as the illustrative studies show, it need not be an horrendous, or ideologically compromising or scientifically complex task to add a cost dimension to the evaluation of mental health services. There are enough examples in the literature of bad costs research to demonstrate that it is not as simple as some people think, but there are also enough examples of good research to encourage further attempts.

Community Mental Health Services↗
PubMed1990

The TAPS project. 3: Predicting the community costs of closing psychiatric hospitals.

The planning of long-term care in the community as an alternative to in-patient care requires accurate information on the likely expense of altering the balance of provision. Unfortunately, as very few long-stay psychiatric hospitals have yet closed, the planning of these resource requirements has had to proceed in a vacuum. By examining the costs of community reprovision for the first 136 people to leave Claybury and Friern Hospitals, a prediction equation has been estimated from existing data which links the hospital-assessed characteristics (including psychiatric symptoms and behavioural problems) of these people to the subsequent cost of community care. About a third of the observed variation in these costs can be explained statistically by these 'baseline' characteristics. However, the first cohorts exhibit fewer behavioural problems and other symptoms of mental illness, they have been in hospital for shorter lengths of time, and they are younger. The prediction equation for the leavers is thus used to extrapolate community costs for those hospital residents yet to leave. It is found that community costs are lower than hospital costs, not just for the first cohorts of leavers, but for the full populations of the two hospitals scheduled to close.

Adult↗
PubMed1990

Gene and haplotype frequencies of HLA antigens in 269 patients with Crohn's disease.

Evidence of strong genetic markers in Crohn's disease (CD) is still absent. Many investigations have focused on HLA antigens, with conflicting results. To obtain more detailed information on the relation of HLA to the disease, we used the HLA data from 269 CD patients to compute the maximum-likelihood estimates of HLA gene and haplotype frequencies. These results provide further evidence that HLA B44 and Cw5 do indeed play a role in the development of CD. Furthermore, it is conceivable from our results that HLA Cw7 may protect against being affected with this disease.

Chi-Square Distribution↗