[Depressive states and chronic asthenic syndromes in general practice]

It has been shown in Great Britain that general practitioners fail to recognize as many as 50% of the cases of depressive illness that present to them. The diagnosis is missed particularly when it is the physical type of symptom, such as asthenia, that is prominent. The Royal College of Psychiatrists, in association with the Royal College of General Practitioners, has launched the "Defeat Depression" campaign which includes amongst its aims the intention to provide up-to-date educational materials to family doctors on the recognition and treatment of depression. We have held two consensus meetings jointly with psychiatrists and primary care physicians and the results have been published in the British Medical Journal (2). One of our key recommendations is that, when medication is used to treat depressive illness in general practice, the antidepressants should be continued for six months after full remission has taken place. At present patients in general practice take their drugs for a total of three or four weeks. One of the reasons for patients abandoning their medication prematurely has been revealed by surveys that we have carried out on the general public. The lay person has little confidence in the efficacy of antidepressants and, perhaps more importantly, believes that they are addictive. It is therefore no surprise, then, that patients are keen to stop their antidepressants before they become dependent on them.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparative studies of UV-induced DNA cleavage by analogues of iodoHoechst 33258

Following the earlier demonstration that iodo-Hoechst 33258 sensitizes DNA and cells to UVA, presumably mediated by formation of a carbon-centred radical on the ligand upon dehalogenation, three isomeric analogues of iodo-Hoechst 33258 have now been studied. The isomers differ in the location of the iodine atom in the phenyl ring of the ligand, relative to the site of attachment of the bibenzimidazole moiety, and are accordingly denoted ortho-, meta- and para-iodoHoechst. Comparison of the ligands with respect to induction of DNA ssb in pBR322 DNA revealed a wide range of activity; (D37's vary by a factor of 37), decreasing in the order: ortho- > meta- and para- > iodoHoechst 33258. Preliminary dehalogenation studies suggest that the higher activity of the ortho isomer results more from increased cross-section for dehalogenation than from increased efficiency of strand breakage per dehalogenation event. However, the chemistry of strand breakage by the ortho-isomer is distinctive, and tentatively assigned to initial attack at the 1'-deoxyribosyl carbon; the other two isomers, like iodo-Hoechst 33258, attack the 5'-carbon. The results are discussed in terms of the spectrum of DNA strand breakage chemistry associated with ionizing radiation, and the potential of DNA strand breaking agents such as the iodoHoechst compounds to study the chemical and biological consequences of the different subclasses of initial DNA damage.

Androgen suppressive effect of GnRH agonist in ovarian hyperthecosis and virilizing tumours

OBJECTIVE

Recent studies have suggested that androgen secretion by ovarian virilizing tumours may be gonadotrophin dependent. The aim of this study was to investigate the suppressive effect of GnRH agonist administration on androgen secretion in women with such tumours.

DESIGN AND PATIENTS

A single i.m. injection of D-Trp-6-GnRH (GnRHa), 3.75 mg, was given to five unrelated patients referred for clinical symptoms of virilization with plasma testosterone (T) levels greater than 7 nmol/l but with normal dehydroepiandrosterone sulphate (DHEAS) levels. Diagnoses of adrenal tumour or a non-classical 21-hydroxylase deficiency were screened for by the dexamethasone suppression test, ACTH stimulation test and adrenal CT scanning, and were ruled out in all patients. The one premenopausal patient received cyproterone acetate in a dose of 50 mg twice daily for 3 weeks, starting 1 week before GnRHa administration.

MEASUREMENT

Testosterone, androstenedione (A), DHEAS, 17-hydroxyprogesterone (OHP), LH and FSH plasma concentrations were measured by radioimmunoassay of blood samples taken before and 3 weeks after GnRHa.

RESULTS

In each patient, GnRHa suppressed gonadotrophin levels and reduced T and A to the range for normal control women. With these results, and because accurate localization of an ovarian androgen secreting tumour could not be achieved by pelvic ultrasonography and CT scanning, exploratory laparotomy was undertaken. A Sertoli-Leydig cell tumour was found in the premenopausal patient, and granulosa cell tumour, hilus cell tumour and two hyperthecoses in the four post-menopausal patients. After bilateral ovariectomy and hysterectomy in the post-menopausal woman and after unilateral ovariectomy in the premenopausal women, androgen levels were normalized.

CONCLUSIONS

In virilized women, the findings of increased serum testosterone with normal gonadotrophin levels and GnRHa suppression of gonadotrophins leading to normalization of testosterone levels, suggest that various ovarian androgen-secreting tumours, as well as hyperthecosis, are not autonomous but apparently depend upon continuous gonadotrophin stimulation.

Characterization of defined ompR mutants of Salmonella typhi: ompR is involved in the regulation of Vi polysaccharide expression

The ompB operon, comprising the ompR and envZ genes, was cloned from a Salmonella typhi Ty2 cosmid bank and characterized by DNA sequence analysis. The S. typhi ompR and envZ genes contained open reading frames encoding proteins of 240 and 451 amino acids, respectively. Comparison with the Salmonella typhimurium OmpB protein sequences revealed 99.5% homology. The DNA sequence data were used to identify appropriate restriction sites for generating a defined deletion of 517 bp within the open reading frame of the ompR gene. This deletion was introduced by homologous recombination into the chromosomes of two S. typhi strains which already harbored defined deletions in both the aroC and aroD genes. The presence of the deletions within ompR was confirmed by Southern hybridization and sequencing of the DNA fragments surrounding the deleted regions by PCR. The S. typhi ompR mutants displayed a marked decrease in OmpC and OmpF porin expression as demonstrated by examination of outer membrane preparations. It was also found that S. typhi strains harboring the defined ompR deletions no longer agglutinated with Vi antiserum. However, when a functional ompB operon was introduced back into the S. typhi ompR mutants, either on a multicopy plasmid or as a single-copy chromosomal replacement, the Vi+ phenotype was restored. The levels of Vi synthesis were also found to be sensitive to different concentrations of sodium chloride present in the growth medium, although the levels of sensitivity varied between different isolates of S. typhi. It is therefore concluded that the ompR-envZ two component regulatory system plays an important role in the regulation of Vi polysaccharide synthesis in S. typhi and that one of the environmental signals for this regulation may be osmolarity.

Clinical and biochemical characteristics of collapsed ultra-marathon runners

To evaluate the characteristics of runners with exercise-associated collapse (EAC), we studied the time of onset of collapse, rectal temperatures, cardiovascular status, and incidence of readily identifiable medical conditions in 46 male athletes who collapsed during or after a 56-km ultramarathon footrace run on a cool day. Data were compared with 65 control runners who did not collapse in the same race. Weight changes during recovery were studied in a subsample of both groups. The majority (85%) of runners with EAC collapsed after they had completed the race; rectal temperatures (38.5 +/- 1.3 degrees C, mean +/- SD; range 35.5-42.0 degrees C) and supine heart rates (87.5 +/- 17.2 min-1; range 60-138) were only modestly elevated. Postrace serum sodium concentrations, changes in plasma volume, and mass during recovery were not significantly different from values in control runners. We conclude that: (i) most cases of EAC (85%) occur after the finish line; (ii) runners collapsing during the race are more likely to have a readily identifiable medical condition than runners collapsing after the finish line; (iii) runners collapse most frequently near cutoff times for medals and race closure times; and (iv) 16% of EAC casualties and 19% of control runners have identifable biochemical abnormalities.

Arthroscopic lateral ankle stabilization

The indications for arthroscopic stabilization include those patients with isolated ruptures or strains of the ATF. The procedure is particularly convenient for patients with ankle joint pathology that is already most commonly treated arthroscopically, such as chronic instability, in which inflamed synovium or meniscoid bodies are to be excised. Although significant stability can be gained with this technique, injuries that result in damage to the calcaneofibular ligament may require additional open surgery, since this ligament cannot be visualized arthroscopically. However, the anchoring techniques described in this article can still be used when performing open surgery.

Silent exertional myocardial ischemia in the elderly: a quantitative analysis of anginal perceptual threshold and the influence of autonomic function

OBJECTIVE

To assess the perception of angina in the elderly and its relationship to autonomic function.

DESIGN

Prospective cohort study of patients with exertional ischemia.

SETTING

Medical, geriatric and cardiac outpatient clinics in two centers.

PARTICIPANTS

All subjects had ischemic heart disease as evidenced by positive treadmill stress tests and, in some, diagnostic angiography and/or documented Q wave infarction. In the first study (I), 37 older patients (range 70-82 years) and 39 younger patients (range 42-59 years) were studied. In a subsequent study (II), a further 49 patients were divided into 2 groups: those with good perception of angina (Anginal Perception Threshold < 15 seconds, group A, 26 patients) and those with no angina despite ischemia (group B, 23 patients).

MEASUREMENTS

Anginal perceptual threshold (APT), age, cardiovascular autonomic function, and blood pressure were measured. APT was defined as the time between onset of 1 mm ST depression to the onset of angina during treadmill stress testing. Autonomic function was studied using heart rate ratios before and after the valsalva maneuver, heart rate responses to deep breathing, and heart rate and blood pressure responses to standing.

RESULTS

In study I, APT in the older patients was delayed by a median value of 49 seconds [79 (range 15-188) versus 30 (-99 to 97) seconds in the younger patients, P < 0.001]. There was no significant correlation between prolonged APT and autonomic dysfunction when younger and older groups were analyzed independently or together. When, however, the high APT subgroup (APT > 30 seconds) was analyzed separately, there was a significant correlation between APT prolongation and impaired valsalva response (r = -0.4; P < 0.005). In study II, 21 of 23 patients (91.3%) with positive exercise test but with no angina (group B) had at least one abnormal autonomic function test compared with 5 of 26 (19%) patients with good anginal perception (group A). Of note, group A was significantly younger than group B [60 (53-63) years vs 66 (62-70 years, P < 0.001].

CONCLUSION

Elevation of APT in the elderly suggests that warning of critical myocardial ischemia is delayed. Autonomic dysfunction may be one of the underlying mechanisms.

Comparative studies of UV-induced DNA cleavage by structural isomers of an iodinated DNA ligand

PURPOSE

To evaluate the importance of the position of the halogen atom in iodinated DNA-binding bibenzimidazoles, with respect to sensitization of UV-A-induced DNA breakage.

METHODS AND MATERIALS

Three analogues of iodoHoechst 33258, denoted ortho-, meta- and paraiodoHoechst, according to the site of iodine substitution, were synthesized. Plasmid DNA (pBR322) was used to assay UV-A-induced DNA single-strand breaks (ssbs). The location of the sites of strand breakage was determined by DNA sequencing gel analysis, using a 32P-endlabelled oligoDNA with a single binding site for the ligands.

RESULTS

A clear trend in decreasing activity of sensitization of UV-induced DNA ssbs was established: ortho- > meta-, para- > iodoHoechst 33258. The sequencing gel studies showed that orthoiodoHoechst was distinct from the other three compounds, with respect to the sites of DNA strand breakage and the chemistry of the cleavage reaction.

CONCLUSION

The position of iodine substitution in iodinated bibenzimidazoles determines the location of the carbon-centered radical on the ligand in the minor groove of DNA. DNA strand cleavage is mediated by abstraction of a nearby deoxyribosyl H-atom. Hence, the position of the radical species determines: which deoxyribosyl group is attacked (i.e., site of cleavage relative to the ligand binding site); which H-atom is abstracted, more specifically which of the five deoxyribosyl carbons is involved (i.e., the chemistry of the cleavage reaction), and the stereochemistry of the transition state for the H-atom abstraction (and hence the efficiency or extent of strand breakage). The ortho-compound represents the best example to date of iodinated DNA ligands designed as potential radiation sensitizers, as an extension of the well-established sensitization by halogenated DNA precursors.

Phosphate transport in osteoblasts from normal and X-linked hypophosphatemic mice

Human hypophophatemic vitamin D-resistant rickets (X-linked hypophosphatemia-XLH) is characterized by hypophosphatemia, a decreased tubular reabsorption of phosphate (P(i)) and defective skeleton mineralization. Utilizing a mouse model (Hyp) of XLH, which demonstrates biological abnormalities and skeletal defects of XLH, we analyzed sodium-dependent phosphate transport in isolated osteoblasts derived from the calvaria of normophosphatemic and hypophosphatemic mice. Initial rates of phosphate uptake by normal and Hyp osteoblasts showed similar slopes. Osteoblasts from both normal and Hyp mice exhibited saturable, sodium-dependent phosphate transport with apparent Vmax and Km values not significantly different (normal mice, Vmax = 24.30 +/- 3.45 nmol/mg prot. 10 min, Km = 349.49 +/- 95.20 mumol/liter; Hyp mice, Vmax = 23.03 +/- 3.41 nmol/mg prot. 10 min, Km = 453.64 +/- 106.93 mumol/liter, n = 24). No differences were found in the ability of normal and Hyp osteoblasts to respond to P(i) transport after 5 hours of P(i) deprivation. Both cell types exhibited a similar increase in cAMP in response to PTH. The accumulated results demonstrate that P(i) uptake and transport in normal and Hyp mouse osteoblasts is a sodium-dependent saturable process. As osteoblast P(i) uptake and transport is apparently normal in the Hyp mouse model of XLH, the "osteoblastic failure" described for the Hyp mouse should be attributed to other mechanism(s).

HLA class I gene, antigen and haplotype frequencies in New Zealand Maori and Europeans

AIM

To determine class I HLA gene, antigen and haplotype frequencies for New Zealand Maori and Europeans.

METHODS

Statistical analysis was performed using accumulated data from Maori (n = 576) and European (n = 1747) parentage studies.

RESULTS

HLA class I gene, antigen and haplotype frequencies are as tabulated. Significant statistical differences were shown to exist between New Zealand Maori, New Zealand Europeans and Europeans. Gene frequencies of HLA A1, 3, 9, 11, 19 and HLA B7, 8, 12, 16, 22, and 40 differed significantly between New Zealand Maori and New Zealand European data. Gene frequencies of HLA A1 and B12 differed significantly between New Zealand European and European data.

CONCLUSIONS

This HLA frequency data can be used for calculating more reliable indices of paternity or for determining the potential availability of matched organs for transplantation, as well as for anthropological studies. The data may also be useful in forensic investigations.

The pattern of diagnosed HIV infection in Australia, 1984-1992

OBJECTIVE

To describe the pattern of newly diagnosed HIV infection in Australia, between 1984 and 1992.

METHODS

State and Territory health authorities reported cases of newly diagnosed HIV infection to the national HIV surveillance centre. Information sought on each case included the State or Territory of diagnosis, the case identifying number, the sex, date of birth and postcode of residence of the person with newly diagnosed HIV infection, the source of exposure to HIV and the date of specimen collection for the diagnosis of infection.

RESULTS

By the end of December 1992, a total of 16,765 cases of newly diagnosed HIV infection had been reported in Australia. The annual number of cases declined between 1985 and 1992. Most diagnoses were among males, and exposure to HIV was attributed to male homosexual contact for more than 80% of cases for which information on exposure to HIV was available. Cases of HIV infection attributed to heterosexual contact represented an increasing proportion of the annual number of diagnoses over the period 1985-1992, among both men and women.

CONCLUSION

National surveillance for newly diagnosed HIV infection has complemented national surveillance for diagnoses of AIDS as a key mechanism for monitoring the course of the HIV epidemic in Australia. The pattern of newly diagnosed HIV infection was similar to the pattern of AIDS diagnoses, with the overwhelming majority of diagnoses of infection being in adult males whose exposure to HIV was attributed to homosexual contact. Limitations of HIV surveillance include the lack of information on HIV testing patterns, incomplete information on HIV exposure histories and duplication of reported diagnoses.

Serum factor in Miller-Fisher variant of Guillain-Barré syndrome and neurotransmitter release

Serum IgG autoantibodies to GQ1b ganglioside are associated with the acute phase of the Miller-Fisher syndrome (MFS). We investigated the effects of three anti-GQ1b-positive MFS sera in the mouse phrenic-nerve/diaphragm preparation. Miniature endplate potential frequencies increased eight-fold within 25 min, declined rapidly, and ceased altogether after 3 h, when nerve stimulation no longer evoked a response. One MFS convalescent serum (anti-GQ1b negative) and sera from healthy controls and from patients with other neurological diseases were without effect. Thus muscle weakness in MFS may be caused by a serum factor, likely to be GQ1b antibody, that leads to failure of acetylcholine release from motor nerve terminals.

The population dynamics of parasitic helminth communities

This paper describes a mathematical model which allows us to compare the data collected from short-term cross-sectional surveys with the population dynamics of host and parasite populations over longer periods of time. The model extends an earlier framework for two parasite species in one host, to one for an arbitrary number of parasite species. We show that the conditions necessary for the coexistence of two parasite species extend to expressions for the coexistence of three or more parasite species. Furthermore, the model suggests that those species which form the 'core' of the parasite community are those whose high fecundity and transmission efficiency permit them to colonize hosts readily. In contrast, those species which are classified as 'satellite' species of the community are either species with low fecundity, or low transmission efficiencies. This work confirms earlier studies that suggest that increasing degrees of aggregation are crucial in allowing several species of parasites to coexist in the same species of hosts. The properties of the model are compared with patterns observed in data collected for helminth parasites of Anolis lizards, wood mice and eels. This combined theoretical and empirical approach confirms the importance of the life history strategies of the parasite in determining the abundance of each species in the community. It suggests that studies of parasite community structure have to pay more attention to the strategies pursued by each individual species before interactions between species are considered.

Bluff your way in epidemic models

The literature on the mathematical modelling of infectious diseases has grown enormously in recent years, both in quantity and quality. Here, we briefly point to the purposes of these modelling exercises and introduce the main ideas behind compartmental models, to act as a guide to the (bio)mathematical literature that is less directly accessible.

Immunity after treatment of human schistosomiasis: association between cellular responses and resistance to reinfection

Previous studies have demonstrated the development of an age-dependent resistance to reinfection after chemotherapeutic cure of the helminthic parasite Schistosoma mansoni. Here we report on a longitudinal investigation of cell-mediated responses in infected individuals before and after treatment which was designed to outline those parameters important in mediating a protective response. A well-defined study group of 89 individuals with an age range of 9 to 35 years was selected from an area of high S. mansoni transmission in the Machakos district of Kenya. Peripheral blood mononuclear cell proliferation and cytokine production (interleukin-2 [IL-2], gamma interferon IL-5, IL-4, and tumor necrosis factor) in response to different crude life cycle-stage antigens of S. mansoni were assessed longitudinally in vitro before, 3 months after, and 1 year after treatment. Detailed statistical analyses of the results from this study have indicated a clear negative association between the proliferative responses to adult- and schistosomulum-stage antigens and subsequent reinfection intensity in older individuals (14 to 35 years) which was not present in the younger individuals (9 to 13 years). This association was significant even after the effects of age, sex, and exposure had been accounted for in multiple regression analyses. Cytokines were detected predominantly in response to adult worm and egg antigen extracts. An inverse association between the two cytokines gamma interferon and IL-5 was detected in response to all antigens at the three time points investigated, indicating cross-regulation in the production of these two mediators. Differences in antigen-specific cytokine levels between the two age groups were detected, with significantly higher IL-5 levels detected in the older (more resistant) age group. An inverse correlation between this cytokine and reinfection was detected but could not be dissociated from the effects of age and exposure in multiple regression analysis.

Expression of P.69/pertactin from Bordetella pertussis in a baculovirus/insect cell expression system: protective properties of the recombinant protein

The surface antigen P.69/pertactin of Bordetella pertussis has been expressed using the polyhedron promoter of baculovirus in cultured insect cells. Either full-length or truncated prn DNA was used to express P.69 pertactin. The full-length gene gave rise to low levels of P.93 precursor protein, some of which was processed to P.69. The shortened prn expressed P.69 pertactin directly at levels up to 3.5 mg per litre. P.69 vaccinated animals were protected against aerosol challenge with virulent B. pertussis bacteria.