Hepatic iron and iron absorption in hemochromatosis

The relationship between iron absorption and hepatic iron was studied in 21 patients with hemochromatosis. Iron absorption was studied using 59Fe and total body counting and hepatic iron was measured by atomic absorption spectrophotometry. Iron absorption was inversely related to hepatic iron concentration (r = -0.51, p = 0.009) in this patient population. This observation suggests that iron absorption is regulated by body iron stores even in hemochromatosis, and does not support the hypothesis that the primary metabolic defect in hemochromatosis is a deregulation of iron absorption in relation to iron stores.

Scales to measure perceived control developed specifically for people with tablet-treated diabetes

Scales to measure perceived control of tablet-treated diabetes were adapted from a measure designed previously for insulin users. Development of the new scale is described and the psychometric properties are examined with responses from 187 tablet-treated patients. The scales consist of seven subscales which may be combined to provide three composite scores indicating the extent to which respondents perceive Personal Control, Medical Control, and Situational Control over their diabetes. Relationships between subscales and composite scores were similar to those found previously for insulin users. Patients were significantly more likely (p less than 0.001) to make attributions to Personal Control for their diabetes management rather than to Medical or Situational Control. As before, predictable biases were found in attributions to positive and negative outcomes. Correlations with medical and other psychological variables indicated that, as expected, stronger perceptions of Personal Control were associated with lower HbA1 levels (r = -0.14; p less than 0.05), lower percent ideal body weight (r = -0.24; p less than 0.01), less Anxiety (r = -0.15; p less than 0.05), greater Positive Well-being (r = 0.21; p less than 0.01) and greater Satisfaction with treatment (r = 0.34; p less than 0.001). Complementary relationships were found with the measure of Situational Control. Wallston and Wallston's speculative Locus of Control typology was investigated using the new measures, and the findings provided support for the value of this approach.

Measures of psychological well-being and treatment satisfaction developed from the responses of people with tablet-treated diabetes

Psychological outcome measures of Well-being and Treatment Satisfaction have been designed and developed for people with tablet-treated Type 2 diabetes. The Well-being scale includes three six-item sub-scales to measure Depression, Anxiety, and Positive Well-being. A prime consideration when selecting items for the psychological well-being measures was to minimize the confounding of diabetic symptomatology with the somatic symptoms of depression and anxiety. Cronbach's alpha indicated that each of the Well-being sub-scales and the Treatment Satisfaction scale was internally reliable (alphas ranged from 0.70 to 0.88) and evidence for construct validity was provided by predicted associations with other variables collected at the time of the study. For example, lower Well-being scores were associated with being overweight (Depression: p less than 0.05; Anxiety: p less than 0.001) while greater Satisfaction with Treatment was associated with lower HbA1 levels (p less than 0.001) and lower percent ideal body weight (p less than 0.01). These scales should prove particularly useful where measures of quality of life are required to complement metabolic variables when evaluating new treatments, education programmes, and other interventions, or in the routine auditing of established methods of treatment.

Virucidal activity of disinfectants: studies with the poliovirus

The activity of various disinfectants against poliovirus (Sabin 1 an) was assessed using surface and suspension tests. The surface test showed that 2% glutaraldehyde and high concentrations of hypochlorites (9200 ppm avCl2) were effective (i.e. greater than or equal to 4 log10 reduction) against a dried virus suspension in 1 min. Diluted aldehydes ('Sporicidin' and 'Gigasept'), lower hypochlorite concentrations (1000 ppm avCl2) and peroxides (3%) were less effective while 70% ethanol showed variable results; 70% isopropanol was ineffective in 10 min. In the suspension tests hydrogen peroxide (3% and 6%) and 70% ethanol were ineffective in 1 min.

Health belief scales developed specifically for people with tablet-treated type 2 diabetes

The design and development of scales to measure diabetes-specific health beliefs of patients treated with oral hypoglycaemic agents and diet are described. The scales, which were developed from the responses of 187 tablet-treated patients, measure perceived Benefits of, and Barriers to Treatment, and perceived Severity of, and Vulnerability to Complications of diabetes and other disorders unrelated to diabetes. Cronbach's alpha indicated that each scale was internally reliable (alpha = 0.67 to 0.89) and construct validity was indicated by expected correlations between the scales and other variables including measures of blood glucose control, body weight, and psychological well-being. Thus, patients who were overweight and/or had higher glycosylated haemoglobin (HbA1) levels perceived their treatment to be less 'Cost-effective' (Benefits less Barriers), rated Complications as being more severe, and reported greater Vulnerability for themselves and the 'average person' with diabetes to these Complications (p less than 0.05 to p less than 0.01). Furthermore, respondents with higher Depression and Anxiety scores and lower Positive Well-being and Treatment Satisfaction scores reported greater Vulnerability to Complications for themselves and the 'average person', and also felt that their treatment was less 'Cost-effective' (p less than 0.01 to p less than 0.001). The measures are likely to be particularly useful in studies which assess the efficacy of interventions in modifying health beliefs with a view to achieving desired behaviours. They may also be useful as an instrument of audit if indicators about the suitability of possible interventions are sought.

Relationship between the pharmacokinetics and toxicity of mitozolomide

The cytotoxic drug mitozolomide has been found to cause unpredictably severe thrombocytopenia during phase I and II clinical trials. In an attempt to relate dose and pharmacokinetic parameters to toxicity, we measured plasma concentrations of mitozolomide in 14 patients with a range of malignancies. There were significant correlations (Spearman rank correlation test) between drug clearance and AUC and white blood cell nadir. The pharmacokinetic and toxicity data were not normally distributed; therefore, it was not possible to construct predictive nomograms for toxicity based on linear regression analysis.

Metastatic vipoma arising from colonic primary tumour

We describe a case of a tumour of the sigmoid colon with hepatic metastases in a patient with previously documented ulcerative colitis. A diagnosis of metastatic vipoma was made on the basis of high plasma levels of vasoactive intestinal polypeptide (VIP). Profuse diarrhoea and profound metabolic upset were corrected by the use of a somatostatin analogue SMS 201-995, whilst conventional cytotoxic therapy produced a significant tumour response with return of the plasma VIP level to normal.

Structural characterization of HIV reverse transcriptase: a target for the design of specific virus inhibitors

The reverse transcriptase (RT) of HIV is an important target for chemotherapy as demonstrated by the effective treatment of AIDS patients with zidovudine, a potent inhibitor of RT. Structural studies of HIV RT were therefore undertaken with a view to designing more effective inhibitors. To obtain sufficient quantities of enzyme for these studies the reverse transcriptase gene of HIV was cloned into a high level expression plasmid yielding reverse transcriptase at a level of 10% of the total Escherichia coli proteins. Monoclonal antibodies to RT were raised in mice and have been used to purify the enzyme by immunoaffinity chromatography. Crystallization of the enzyme has been achieved and studies are underway to determine its three-dimensional structure. In addition, carboxy-terminal truncated mutants were prepared by inserting stop codons into the gene at appropriate sites. The proteins expressed were analysed for RT and RNase H activity and used for mapping RT epitopes. This, together with previous data on site-directed mutagenesis of conserved regions of HIV RT has helped to map some of the structural and functional regions of the enzyme.

HIV-1 reverse transcriptase: crystallization and analysis of domain structure by limited proteolysis

Bacterially expressed recombinant HIV-1 reverse transcriptase is active as both a homodimer of Mr 66,000 subunits and a heterodimer of Mr 66,000 and 51,000 subunits. The heterodimer is formed by cleavage of a C-terminal fragment from one Mr 66,000 polypeptide, which occurs during purification and crystallization of reverse transcriptase. Thus, crystals obtained from purified Mr 66,000 polypeptide preparations consisted of an apparently equimolar mixture of Mr 66,000 and 51,000 polypeptides, which were apparently analogous to the Mr 66,000 and 51,000 polypeptides detected in HIV-infected cells and in virions. Limited proteolysis of the homodimer with alpha-chymotrypsin also resulted in cleavage to a stable Mr 66,000/51,000 mixture, and proteolysis with trypsin resulted in the transient formation of some Mr 51,000 polypeptide. These results are consistent with the reverse transcriptase molecule having a protease-sensitive linker region following a structured domain of Mr 51,000. Further digestion with trypsin resulted in cleavage of the Mr 51,000 polypeptide after residue 223, yielding peptides of apparent Mr 29,000 and 30,000. A minor peptide of Mr 40,000 was also produced by cleavage of the Mr 66,000 polypeptide after residue 223. About half the original Mr 66,000 polypeptides remained resistant to proteolysis and existed in complex with the above peptides in solution. During both chymotrypsin and trypsin digestion there was an increase in the reverse transcriptase activity caused by a doubling of Vmax with little change in Km for dTTP.(ABSTRACT TRUNCATED AT 250 WORDS)

Osteogenic sarcoma of the ethmoid sinus

A case of osteogenic sarcoma of the ethmoid sinus is reported in a 45 year old man. The tumour extended superiorly through the frontal sinus and involved the medial wall of the left orbit causing diplopia. Treatment comprised partial excision followed by radiotherapy and chemotherapy with symptomatic improvement, although 13 months later the patient died from progressive local and metastatic disease. A possible relationship to previous radiation exposure is discussed.

Structural studies of the acquired immunodeficiency syndrome virus reverse transcriptase

The clinical success of zidovudine has established the human immunodeficiency virus (HIV) reverse transcriptase (RT) as a valid target for the design of drugs to treat acquired immunodeficiency syndrome. In order to facilitate structural studies of this enzyme, expression systems in Escherichia coli, which allow the production of large amounts of RT, have been established. Using this recombinant material the RT has been purified and crystallized. Crystallographic studies currently underway are aimed at elucidating the three-dimensional structure of HIV RT. The availability of a bacterial expression system has enabled structural/functional studies of the RT by site-directed mutagenesis. These studies have identified amino acid residues that are essential for activity of the enzyme and might be involved in substrate binding. It is hoped that structural information of this nature will allow the rational design of HIV RT inhibitors.

Flavone acetic acid: a nonlinear pharmacokinetic model

Flavone acetic acid pharmacokinetics were studied in 31 patients in a phase I clinical trial. The drug was given by i.v. infusions over 1, 1.5, 3, and 6 h at doses ranging from 0.5 to 6.4 g/m2. The pharmacokinetic parameters were determined according to a nonlinear model including Michaelis-Menten-type kinetics. The mean elimination half-life is 4.8 h and the mean volume of distribution of the central compartment, 7.61. Our model predicted a maximal tolerated dose (MTD) of 11.1 g/m2 on the basis of the "therapeutic window" concept, very close to the clinically observed MTD of 10 g/m2. This model is also operational when different protocols of inoculation are considered, such as a divided-dose schedule vs a unique infusion, and indicates that, at the MTD, injections should be made every 72 h to avoid drug accumulation.

A measure of treatment satisfaction designed specifically for people with insulin-dependent diabetes

The psychometric properties of a diabetes-specific treatment satisfaction scale were examined with responses from 128 adults with insulin-dependent diabetes who had used one of three treatment options for a period of 12 months. The reliability of the seven-item measured was found to be satisfactory (Cronbach's Alpha = 0.76) and factor analyses indicated three useful sub-scales (Perceived General Management; Perceived Compatibility with Lifestyle; Perceived Frequency of Hypo/hyperglycaemia). Use of the treatment satisfaction measure in a feasibility study of continuous subcutaneous insulin infusion (CSII) demonstrated the measure's ability to distinguish between three treatment groups (CSII, intensified conventional therapy and conventional therapy). People choosing to use CSII reported significantly greater improvements in satisfaction than those choosing either from of conventional therapy (F = 36.6; df 2, 125; p less than 0.001). If used in conjunction with measures of blood glucose control, the Treatment Satisfaction measure offers the opportunity for a more holistic appraisal of outcomes in studies evaluating and comparing treatments for insulin-dependent diabetes.

Causal attributions of doctor and patients in a diabetes clinic

This study investigated the level of congruence in causal attributions and diabetes-specific perceived control between doctor and patients during routine diabetes clinic consultations. The effectiveness of a strategy for improving the congruence of doctor and patients' attributions was examined. Fifty-four patients with poorly controlled insulin requiring diabetes mellitus were assigned to one of three forms of consultation: (1) routine consultation, (2) a consultation where doctor and patient explicitly negotiated and agreed the nature of the problem(s) to be discussed, (3) consultation as in (2) but doctor and patient negotiated and agreed not only the problems but also their causal attributions for the problems discussed. Analysis of covariance demonstrated that the experimental manipulations were successful in improving problem and attribution congruence across the groups. Predicted mismatches in perceived control between doctor and patient in Group I were demonstrated, and, as expected, were reduced in Groups II and III. The clinical implications of differing levels of congruence in attributions and perceived control were considered in analyses of glycaemic control and patients' satisfaction with their consultation.

Phase I and pharmacokinetic study of flavone acetic acid

Flavone acetic acid is the second in a series of compounds based on the flavonoid aglycone ring structure to be clinically evaluated in malignant disease. Preclinical studies have indicated that a minimum plasma level of 150 micrograms/ml is required before therapeutic efficacy (in a wide range of experimental tumors) is seen in mice; both in vitro and in vivo studies also suggest that the duration of drug exposure is crucial in determining activity. Thus a Phase I trial has been performed in a total of 54 patients using 3 schedules, i.e., a 1-, 3-, and 6-h infusion. In each case, treatment was given once weekly for a minimum of 3 weeks. The maximum tolerated doses were 6.4, 6.4, and 10.0 g/m2, respectively. Dose limiting toxicity was denoted by an intense feeling of warmth and flushing with a 1-h infusion, hypotension with a 3-h infusion, and hypotension and diarrhea with a 6-h infusion. No objective responses were seen in this Phase I trial. The recommended doses for Phase II trials of flavone acetic acid in Europe are 4.8 g/m2 over 1 h or 8.6 g/m2 over 6 h. At these doses the peak plasma concentrations obtained are 650 and 388 micrograms/ml, respectively. Total drug exposure (assessed by an area under the curve greater than 100 micrograms/ml) was approximately 50% greater for the 6-h schedule. This Phase I trial indicates that peak plasma concentrations associated with experimental activity are achievable in humans, although optimal drug exposure times have not yet been defined.

Duplication 7p in a family with t(7;11): association with anomalies of the anterior cranial base

Duplication 7p has been observed in association with several balanced translocations. Of eight previously recorded cases, only one exhibited duplication of the entire short arm of chromosome 7. We report on a newborn infant with multiple congenital anomalies and an abnormal chromosome constitution: 46,XX,-11,+der(11),t(7;11) (p11.1;p15.5)mat. The proposita appeared to possess an isolated duplication of the entire short arm of 7. The patient died at age 4 days because of respiratory complications of meconium aspiration. Clinical and postmortem findings included craniocerebral asymmetry, craniosynostosis of a lambdoid suture, arhinencephaly, hypertelorism, anomalies of the ethmoidal portion of the cranial base, large anterior fontanelle, low set ears, ventricular septal defect (VSD), dysplastic tricuspid and pulmonic valves, hypoplastic genitalia, bilateral dislocated hips, and other minor limb malformations.