Differential recall as a source of bias in epidemiologic research

Differential recall between compared groups is discussed most often in the context of case-control studies. Cases, compared to controls, are suspected of providing a more complete report of their true exposure to an hypothesized risk factor, thereby biasing upwards the estimate of its effect. The present paper describes how differential recall can arise with any observational design in epidemiology; with any class of study variable, not only exposures; and may inflate or deflate the true value of the estimate of effect size. We list a variety of study designs and questionnaire tactics that aim to remedy these problems. The scope and magnitude of the bias created by differential recall and the efficacy of proposed remedies require further study.

Actinomycosis of the greater omentum

A case of histologically proven actinomycosis of the greater omentum is reported. Computed tomography (CT) showed a mass at the greater omentum near the left flank area; it was hypervascular on angiograms and was supplied by the omental artery originating from the splenic artery. Sonography showed that the echogenecity of the lesion was complex. Actinomycosis of the greater omentum, although rare, should be included in the differential diagnosis of omental mass.

Obesity and breast disease. The role of the female sex hormones

An Australian study of 513 women evaluated associations between obesity and both benign and malignant breast disease, and in particular investigated the role of female sex hormones. Women who gained more than 10 kg from early womanhood had a two-fold increase in risk of developing breast cancer, whereas lean women had a greater risk of being treated for benign breast disease. Obese women with breast cancer were more likely to have Stage II tumors but there was no significant association between obesity and tumor size or estrogen and progesterone receptor status. Obesity was strongly associated with the proportions of nonprotein-bound and albumin-bound estradiol, and inversely associated with sex hormone binding globulin (SHBG) levels and the proportion of SHBG-bound estradiol. In addition, age at menarche was inversely associated, and age at menopause directly associated with recalled weight at those time periods. These data demonstrate weight gain as a risk factor for breast cancer, and suggest a possible mechanism supporting its development.

Primary myxoma of the cranium: CT findings

A case of 17-year-old girl with primary myxoma of the cranium is presented. The lesion ballooned the inner and outer tables of the cranium and expanded intracranially, causing neurologic deficits. The lesion is rare and its radiographic, including CT, features are described.

Genetic analysis of eight loci tightly linked to neurofibromatosis 1

The genetic locus for neurofibromatosis 1 (NF1) has recently been mapped to the pericentromeric region of chromosome 17. We have genotyped eight previously identified RFLP probes on 50 NF1 families to determine the placement of the NF1 locus relative to the RFLP loci. Thirty-eight recombination events in the pericentromeric region were identified, eight involving crossovers between NF1 and loci on either chromosomal arm. Multipoint linkage analysis resulted in the unique placement of six loci at odds greater than 100:1 in the order of pter-A10-41-EW301-NF1-EW207-CRI-L581-CRI-L946 -qter. Owing to insufficient crossovers, three loci--D17Z1, EW206, and EW203--could not be uniquely localized. In this region female recombination rates were significantly higher than those of males. These data were part of a joint study aimed at the localization of both NF1 and tightly linked pericentromeric markers for chromosome 17.

PTCA--the initial 100 cases in the Singapore General Hospital

Percutaneous transluminal coronary angioplasty (PTCA) is an increasingly important technique for the treatment of patients with coronary artery disease. One hundred cases of PTCA were performed in Singapore General Hospital between 1985 to September 1988. 87% were males and 13% were females. The mean age of these patients were 55 +/- 9 SD years (range from 28 to 79 years). 85% had angina pectoris, 43% had a previous myocardial infarction and 12% received intravenous streptokinase previously. One hundred and twenty-nine lesions were dilated. 51% of the cases had single, 40% had double and 9% triple vessel disease. 83% had single, 16% double and 1% triple vessel dilatation. The distribution of the cases by vessel location was 64% for LAD, 19% for RCA and 17% for CX. Overall lesion success was 86%, with an increment in the success rate from 76% in 1987 to 89% in 1988. Similarly, the clinical success rate was 86% for the whole group; it increased from 74% to 90% from 1987 to 1988. The mean diameter stenosis was decreased from 86 +/- 14% SD predilatation to 28 +/- 28% SD postdilatation (p less than 0.005). The mean transtenotic gradient was reduced from 60 +/- 17 mmHg SD predilatation to 18 +/- 11 mmHg SD postdilatation (p less than 0.005). There were 14 failures (14%), the majority of which were due to inability transversing the lesion with a guide wire or balloon catheter. Fourteen complications (14%) occurred in these 100 cases of PTCA. 3% required emergent/semiemergent surgical revascularization. There was no mortality. PTCA is now an established mode of therapy for coronary artery disease in Singapore General Hospital.

Tuberous sclerosis with aortic aneurysm and rib changes: CT demonstration

A 24-year-old man with tuberous sclerosis was found to have an aneurysm arising from the abdominal aorta and rib changes including sclerotic thickening, wavy periosteal new bone formation, and a cortical defect filled with soft tissue density.

Clinical diagnosis of late temporal lobe necrosis following radiation therapy for nasopharyngeal carcinoma

This is a preliminary report of 102 patients with clinical diagnosis of late temporal lobe necrosis after radical radiation therapy for nasopharyngeal carcinoma during 1964 to 1983. Histologic verification was available in 12 cases. All but three patients had been treated in our institute using schedules with doses larger than the conventional 200 cGy per fraction. The incidence rate was 1.03%. In our 80 patients with only one course of external irradiation, the doses to the temporal lobes ranged from 1665 to 2127 ret, or 1286 to 1778 brain tolerance unit (btu). The latent interval ranged from 9 months to 16 years. The median observation period is 33 months. The symptomatology, working diagnosis, treatment, and outcome are described. Surgery was hazardous because of the bilaterality of the involvement and exploration for mere verification of diagnosis was unjustified in typical cases. Treatment with corticosteroid achieved durable objective response in 25 (35%) of 72 patients. The importance of early detection and corticosteroid treatment is discussed.

Clinical diagnosis of late temporal lobe necrosis following radiation therapy for nasopharyngeal carcinoma

This is a preliminary report of 102 patients with clinical diagnosis of late temporal lobe necrosis after radical radiation therapy for nasopharyngeal carcinoma during 1964 to 1983. Histologic verification was available in 12 cases. All but three patients had been treated in our institute using schedules with doses larger than the conventional 200 cGy per fraction. The incidence rate was 1.03%. In our 80 patients with only one course of external irradiation, the doses to the temporal lobes ranged from 1665 to 2127 ret, or 1286 to 1778 brain tolerance unit (btu). The latent interval ranged from 9 months to 16 years. The median observation period is 33 months. The symptomatology, working diagnosis, treatment, and outcome are described. Surgery was hazardous because of the bilaterality of the involvement and exploration for mere verification of diagnosis was unjustified in typical cases. Treatment with corticosteroid achieved durable objective response in 25 (35%) of 72 patients. The importance of early detection and corticosteroid treatment is discussed.

Linkage studies with chromosome 17 DNA markers in 45 neurofibromatosis 1 families

A locus for von Recklinghausen neurofibromatosis (NF1) has recently been mapped near the chromosome 17 centromere. We have extended these linkage studies by genotyping 45 NF1 families with three DNA probes known to be linked to the chromosome 17 centromeric region. Of 34 families informative for NF1 and at least one of the three probes, 28 families show no recombinants with the disease gene. These data provide additional support for genetic homogeneity of NF1 and for a primary NF1 locus linked to the chromosome 17 centromere. Among the informative families were 7 families with apparent new NF1 mutations. Our data suggest that these mutations are probably at the chromosome 17 NF1 locus.

Hercon technology for transdermal delivery of drugs

The Hercon controlled drug delivery technology is based on a multi-layered laminated polymeric structure, in which a layer of vinyl chloride copolymer or terpolymer containing the drug is sandwiched between two or more layers of polymeric films. The drug is released from the device at a controlled rate by a process of diffusion through the reservoir and one of the outer layers, which can function as a rate controlling membrane. This basic technology has been successfully utilized for the development and commercialization of Nitroglycerin Transdermal System (NTS, Bolar Pharmaceutical Co., Inc). In vitro and in vivo investigations of transdermal delivery of different other drugs from the Hercon polymeric devices have indicated the feasibility of using this system to meet a variety of therapeutic needs.

Neurological soft signs. Their relationship to psychiatric disorder and intelligence in childhood and adolescence

Sixty-three male and 27 female adolescents known to have had neurological soft signs at the age of 7 years were compared with controls with no soft signs at age 7. Adolescents with early soft signs had significantly lower IQs and were more likely to have a psychiatric disorder characterized by anxiety, withdrawal, and depression. All the girls and 80% (12/15) of the boys with an anxiety-withdrawal diagnosis showed early soft signs. There was no relationship between early soft signs and attention deficit or conduct disorders. Examination of the relative contributions of anxiety at age 7, IQ, and social and family disadvantage to later diagnosis showed that most of the variance was accounted for by soft signs independently of IQ. Soft signs and anxious dependent behavior at age 7 were strongly predictive of persistent psychiatric disorder characterized by anxiety and withdrawal.

Prolonged outbreak of Norwalk gastroenteritis in an isolated guest house

During November and December 1982, a persistent outbreak of gastroenteritis took place in an isolated guest house. An estimated 26% of the changing population of guests and staff developed symptoms. Laboratory studies implicated Norwalk agent as the cause of illness, although the original source of the outbreak could not be established. Information on clinical features of the illness, its mode of spread, and eventual control is presented.

A pre-set ultraviolet dose meter

The design, construction and performance of an ultraviolet radiation (UVR) pre-set dose meter is described. The meter simultaneously displays irradiance, dose, and elapsed time, and incorporates a calibrated variable gain control to permit use with detectors of varying sensitivity. The meter has been developed to permit the automatic administration of UVR dose in photosensitivity testing. The UVR is generated by a Xenon lamp and delivered to the patient via a monochromator and liquid filled light guide. A beam-splitter in the light guide applicator diverts a small fraction (9%) of the UVR onto a photo-diode detector connected to the meter. When the dose recorded by the meter reaches the pre-set value the meter activates a solenoid which closes the monochromator exit slit shutter. This on-line control of the dose ensures that any fluctuations in irradiance are compensated so that the pre-set test dose is always administered to within the 1% accuracy of the instrument.

Hong Kong married abortion applicants: a comparison with married women who elect to complete their pregnancies

The authors compared 130 married abortion applicants with 100 married pregnant women who were attending the antenatal clinic. The abortion applicants were more likely to have had unhappy childhoods, broken homes, sexual pathology and more children. Their neuroticism scores on the Maudsley Personality Inventory were significantly higher. They tended to use either no contraception or unreliable methods. They were older and tended to report more socioeconomic problems. The characteristics of abortion applicants in this study seem to be similar to those reported from other countries.

Blood pressure in the first 6 weeks of life

Systolic blood pressure was measured at frequent intervals during the first 6 weeks of life in 99 normal neonates. Blood pressure rose from a mean of 70 mmHg at age 2 days, to 93 mmHg at age 6 weeks in babies awake; the majority of this rise (14 mmHg) took place in the first 2 weeks of life. The blood pressure measured when infants were asleep was lower than in those awake, but increased in a similar manner. Blood pressure of infants at 2 days was not significantly affected by method of delivery, or by the anaesthesia or analgesia that the mothers received in labour. It was not related to the Apgar score at one or five minutes.

The irreversible binding of benzo[a]pyrene to rat liver macromolecules in vivo and in vitro: effects of agents that influence benzo[a]pyrene metabolism

The present study was carried out to determine the effects of agents that influence benzo[a]pyrene (BP) metabolism in vitro on the irreversible binding of BP to rat hepatic macromolecules in vivo. The irreversible binding of [3H]BP was found to be both dose and time dependent after its intraperitoneal administration to male Wistar rats. The SKF 525-A, at doses of 50 and 75 mg/kg, ip 3 h before BP, decreased the level of binding from control by 31 and 34%, respectively. At 35 mg/kg, SKF-525-A had no effect. Diethyl maleate (0.6 mL/kg, ip) and cysteine (150 mg/kg, ip), 30 and 5 min before BP, respectively, did not alter the binding of BP from control. Oral methadone treatment, previously shown to increase selectively epoxide hydrase activity in male Wistar rats, also failed to alter the amount of BP bound to hepatic macromolecules. 3-Methylcholanthrene (20 mg/kg per day, ip, for 2 days) administered 24 h before BP, decreased the level of binding from control by 30%. Parallel in vitro studies were carried out with the various agents used in vivo.