Cerebral critical closing pressure estimation from Finapres and arterial blood pressure measurements in the aorta

Estimates of cerebral critical closing pressure (CrCP) and resistance-area product (RAP) are often derived using noninvasive measurements of arterial blood pressure (ABP) in the finger, but the errors introduced by this approach, in relation to intra-vascular measurements of ABP, are not known. Continuous recordings of ABP (Finapres and solid-state catheter-tip transducer in the ascending aorta), cerebral blood flow velocity (CBFV, bilateral Doppler), ECG and transcutaneous CO(2) were performed following coronary catheterization. CrCP and RAP were calculated for each of 12,784 cardiac cycles from 27 subjects using the classical linear regression (LR) of the instantaneous CBFV-ABP relationship and also the first harmonic (H(1)) of the Fourier transform. There was a better agreement between LR and H(1) for the aortic measurements than for the Finapres (p < 0.000,01). For LR there were no significant differences for either CrCP or RAP due to the source of ABP measurement, but for H(1) the differences were highly significant (p < 0.000,03). The coherence functions between either CrCP or RAP values calculated with aortic pressure (input) or the Finapres (output) were significantly higher for H(1) than for LR for most harmonics below 0.2 Hz. When using the Finapres to estimate CrCP and RAP values, the LR method produces similar results to intra-arterial measurements of ABP for time-averaged values, but H(1) should be preferred in applications analysing beat-to-beat changes in these parameters.

First Occurrence of Panama Disease in Two Banana-Growing Areas of South Africa

Fusarium wilt (Panama disease) of bananas is well established in two of the five banana production regions in South Africa: Kiepersol (near Hazyview) and southern KwaZulu-Natal. The disease is caused by a soilborne fungus, Fusarium oxysporumSchlechtend.: Fr. f. sp. cubense (E.F. Sm.) W.C. Snyd. & H.N. Hans., which is most commonly introduced into an area by infected plant material or in contaminated soil attached to vehicles, farm machinery, or footwear. In September 2000, banana plants were observed dying at an experimental site in a commercial Cavendish plantation in the Tzaneen area of the Northern Province of South Africa. Symptoms included wilting of leaves (starting from the oldest foliage) and yellow-brown discoloration of vascular tissue in the rhizome and pseudostem. These symptoms are typical of those described for Panama disease of bananas (2). Similar symptoms were observed at another experimental site in a banana plantation in the Komatipoort region of the Mpumalanga Province in November 2000. Komatipoort is currently the largest banana production region in South Africa. Panama disease has not previously been reported in the Tzaneen and Komatipoort regions. Both are at least 200 km away from the other banana production areas in South Africa. Fungal isolations were made from four diseased plants in both Tzaneen and Komatipoort, and the discolored tissue of the pseudostem was placed on potato dextrose agar amended with novobiocin (0.2 g/liter). Single-spore cultures made from developing colonies were identified as F. oxysporum based on morphological characteristics. Isolates were sent to the Cooperative Research Centre for Tropical Plant Protection (CRCTPP) in Australia for identification by means of DNA amplification fingerprinting (DAF) analysis (1). Based on DAF analysis, isolates from Tzaneen and Komatipoort were identical to those in vegetative compatibility group 0120 of F. oxysporum f. sp. cubense ("subtropical" race 4), the causal agent of Panama disease in Kiepersol and southern KwaZulu-Natal. Pathogenicity studies were performed in the greenhouse by inoculating 5-cm Cavendish banana plants with two isolates of F. oxysporum f. sp. cubense from Tzaneen and two isolates from Komatipoort. Ten plants per isolate were inoculated by submerging their roots in a suspension of microconidia (10⁵ spores/ml). Roots of control plants were submerged in sterile distilled water. Within 6 weeks, wilting symptoms developed on the lower leaves of inoculated banana plants, and the central cylinder of the rhizomes turned reddish brown. F. oxysporum f. sp. cubense was reisolated from the diseased tissue to complete Koch's postulates. The outbreaks of Panama disease in Komatipoort and Tzaneen do not appear to have spread further. Both of the infected fields were placed under quarantine, and symptomatic plants were destroyed. References: (1) S. Bentley et al. Phytopathology 88:1283, 1998. (2) R. H. Stover. Fusarial Wilt (Panama Disease) of Bananas and Other Musa Species. CMI, Kew, Surrey, UK, 1962.

Characterisation of Australian isolates of Fusarium oxysporum f. sp. cubense by DNA fingerprinting analysis

Genetic variation among Australian isolates of the fungus Fusarium oxysporum f. sp. cubense (Foc), which causes Fusarium wilt in banana, was examined using DNA amplification fingerprinting (DAF). Ninety-four isolates which represented Races 1, 2, 3, and 4, and vegetative compatibility groups (VCGs) 0120, 0124, 0125, 0128, 0129, 01211, 01213/16, and 01220 were analysed. The genetic relatedness among isolates within each VCG, and between the 8 different VCGs of Foc present in Australia was determined. The DNA fingerprint patterns were VCG-specific, with each VCG representing a unique genotype. The genetic similarity among isolates within each VCG ranged from 97% to 100%. Among the different VCGs of Foc, 3 major clusters were distinguished which corresponded with race. All Race 1 and 2 isolates (VCGs 0124, 0125, 0128, and 01220) were closely related and clustered together, the Race 3 isolates from Heliconia clustered separately, and all Race 4 isolates (VCGs 0120, 0129, 01211, and 01213/16) clustered together. Fifteen isolates from Alstonville, NSW, were characterised because although they were classified as Race 2 based on their recovery from cooking banana cultivars, they belonged in VCG 0124, which had previously contained only Race 1 isolates. The occurrence of more than one race within a VCG means that vegetative compatibility grouping cannot be used to assign pathotype to pathogenic race as previously thought. It was possible to distinguish the Race 1 and Race 2 isolates within VCG 0124 using DNA fingerprinting, as each race produced a unique DNA fingerprint pattern. Among the Australian isolates, DNA fingerprinting analysis identified 9 different VCGs and genotypes of Foc.

Genetic Variation Among Vegetative Compatibility Groups of Fusarium oxysporum f. sp. cubense Analyzed by DNA Fingerprinting

ABSTRACT Genetic variation within a worldwide collection of 208 isolates of Fu-sarium oxysporum f. sp. cubense, representing physiological races 1, 2, 3, and 4 and the 20 reported vegetative compatibility groups (VCGs), was analyzed using modified DNA amplification fingerprinting. Also characterized were 133 isolates that did not belong to any of the reported VCGs of F. oxysporum f. sp. cubense including race 3 isolates from a Heliconia species and isolates from a symptomatic wild banana species growing in the jungle in peninsular Malaysia. The DNA fingerprint patterns were generally VCG specific, irrespective of geographic or host origin. A total of 33 different genotypes were identified within F. oxysporum f. sp. cu-bense; 19 genotypes were distinguished among the isolates that belonged to the 20 reported VCGs, and 14 new genotypes were identified among the isolates that did not belong to any of the existing VCGs. DNA fingerprinting analysis also allowed differentiation of nine clonal lineages within F. oxysporum f. sp. cubense. Five of these lineages each contained numerous closely related VCGs and genotypes, and the remaining four lineages each contained a single genotype. The genetic diversity and geographic distribution of several of these lineages of F. oxysporum f. sp. cubense suggests that they have coevolved with edible bananas and their wild diploid progenitors in Asia. DNA fingerprinting analysis of isolates from the wild pathosystem provides further evidence for the coevolution hypothesis. The genetic isolation and limited geographic distribution of four of the lineages of F. oxysporum f. sp. cubense suggests that the pathogen has also arisen independently, both within and outside of the center of origin of the host.

Generalized transduction in the potato blackleg pathogen Erwinia carotovora subsp. atroseptica by bacteriophage M1

Summary: Using enrichment methods, a new bacteriophage (M1) was isolated, which is capable of generalized transduction in Erwinia carotovora subsp. atroseptica (Eca) strain SCRI1043. M1 is probably a virulent phage and contains double-stranded DNA of approximately 43 kb. Transduction frequencies for a number of chromosomal markers and plasmid pHCP2 were established, and conditions for transduction optimized. UV irradiation of the lysates prior to transduction enhanced the transduction frequency. M1 infected over 25% of Eca strains tested and so may be useful both for the genetic analysis of a number of Eca isolates and for the transductional transfer of selectable markers between strains.

Exercise-induced muscle cramp. Proposed mechanisms and management

Muscle cramp is a common, painful, physiological disturbance of skeletal muscle. Many athletes are regularly frustrated by exercise-induced muscle cramp yet the pathogenesis remains speculative with little scientific research on the subject. This has resulted in a perpetuation of myths as to the cause and treatment of it. There is a need for scientifically based protocols for the management of athletes who suffer exercise-related muscle cramp. This article reviews the literature and neurophysiology of muscle cramp occurring during exercise. Disturbances at various levels of the central and peripheral nervous system and skeletal muscle are likely to be involved in the mechanism of cramp and may explain the diverse range of conditions in which cramp occurs. The activity of the motor neuron is subject to a multitude of influences including peripheral receptor sensory input, spinal reflexes, inhibitory interneurons in the spinal cord, synaptic and neurotransmitter modulation and descending CNS input. The muscle spindle and golgi tendon organ proprioceptors are fundamental to the control of muscle length and tone and the maintenance of posture. Disturbance in the activity of these receptors may occur through faulty posture, shortened muscle length, intense exercise and exercise to fatigue, resulting in increased motor neuron activity and motor unit recruitment. The relaxation phase of muscle contraction is prolonged in a fatigued muscle, raising the likelihood of fused summation of action potentials if motor neuron activity delivers a sustained high firing frequency. Treatment of cramp is directed at reducing muscle spindle and motor neuron activity by reflex inhibition and afferent stimulation. There are no proven strategies for the prevention of exercise-induced muscle cramp but regular muscle stretching using post-isometric relaxation techniques, correction of muscle balance and posture, adequate conditioning for the activity, mental preparation for competition and avoiding provocative drugs may be beneficial. Other strategies such as incorporating plyometrics or eccentric muscle strengthening into training programmes, maintaining adequate carbohydrate reserves during competition or treating myofascial trigger points are speculative and require investigation.

Fusarium wilt of banana in Australia: a review

The history of Fusarium wilt of bananas (caused by F. oxysporum f.sp. cubense) and the research conducted on the disease in Australia is summarised in this review. Subjects covered include the classification of banana cultivars, the cultivars in production in the Australian banana industry, the distribution and diversity of the pathogen in Australia and pathogenicity and control of the disease.

A clinical and pharmacokinetic study of high-dose carboplatin, paclitaxel, granulocyte colony-stimulating factor, and peripheral blood stem cells in patients with unresectable or metastatic cancer

We have developed a regimen incorporating multiple cycles of high-dose carboplatin and fixed-dose paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) with granulocyte colony-stimulating factor and peripheral blood stem cell support given every 21 days for up to four cycles. Our phase I study of this regimen has treated 26 patients with good performance status and histologically documented unresectable or metastatic carcinoma, sarcoma, or melanoma, 21 of whom received all planned courses every 21 days. Paclitaxel 250 mg/m2 was infused over 24 hours, followed by a 1-hour carboplatin infusion, with doses escalated between area under the concentration-time curve (AUC) targets of 8 and 20. Considering the carboplatin doses administered (two to three times those generally achieved with growth factor support), toxicity has been relatively modest. The median duration of grade 4 neutropenia and thrombocytopenia was not significantly different between the AUCs of 8 and 18, which proved to be the maximum tolerated carboplatin dose. Twelve courses were associated with hospitalization for neutropenic fever or catheter-related thrombophlebitis. One treatment-related death occurred, and severe toxicity caused withdrawal of two patients treated at the AUC of 20. Peripheral neuropathy was the most common serious nonhematologic complication. Pharmacokinetic analysis showed significantly lower measured versus predicted AUC values. Among 25 evaluable patients, preliminary results show one complete response (ovarian cancer) and 11 partial responses, including four in patients with non-small cell lung cancer. Additional issues to be addressed include the effect of a shorter (or longer) paclitaxel infusion on the carboplatin AUC (and the incidence of toxicity) and whether the discrepancy between actual and predicted AUCs (greater in our study than reported elsewhere) is due to the variability of creatinine clearance-determined glomerular filtration rate or to altered carboplatin pharmacokinetics when a short high-dose infusion follows paclitaxel. Additional patients are being accrued at the AUC of 18.

Underutilization of isoniazid chemoprophylaxis in tuberculosis contacts 50 years of age and older. A prospective analysis

STUDY OBJECTIVES

To examine the utilization of chemoprophylaxis for tuberculosis in certain high-risk groups, ie, infected contacts 50 years and older, and to study the safety of isoniazid (INH) preventive therapy in such persons.

DESIGN

From 1987 to 1992, two-part questionnaires were sent to each of the regional health offices within the 95 counties of Tennessee to document cases of purified protein derivative skin test conversion or reaction among close contacts of new patients with active tuberculosis. Infected contacts 50 years and older were included in the study.

METHODS

Data collected from these questionnaires were grouped according to age, sex, race, liver functions test (LFT), and whether chemotherapy was completed. Reasons for early discontinuation were also recorded. High values of LFTs were classified in the various groups as either twofold elevation or greater than threefold elevation.

RESULTS

Of the 829 responses for persons fitting the criteria for INH chemoprophylaxis, 415 began treatment; 249 (60%) of those completed the full course (9 months) and 166 stopped prematurely. Of the 414 persons (50%) who did not start preventive therapy, 233 (56.5%) respondents listed age as the reason. No patients started on a regimen of therapy developed hepatitis. Of those completing therapy, 6.9% had a rise in liver enzyme values but remained asymptomatic for hepatitis. Liver enzyme level elevation was significantly higher among patients who discontinued therapy, particularly white women, than those who completed the full course. Asymptomatic liver enzyme level elevation (> or = 3 times normal value), private practitioners' preferences, and patients arbitrarily stopping therapy were the leading reasons for incomplete INH preventive therapy.

CONCLUSION

We conclude that 30% of tuberculosis-infected contacts deserving chemoprophylaxis were actually provided the full benefit of INH preventive therapy, indicating underutilization of this prevention strategy, particularly in contacts older than 50 years.

Smoking in hotels: prevalence, and opinions about restrictions

Exposure to high levels of environmental tobacco smoke can occur in hotels. Controversy exists about smoking regulation on licensed premises. This survey of 138 people attending one of three Newcastle hotels during 1993 found that 57 per cent of respondents were nonsmokers. Fifty-eight per cent (95 per cent confidence interval (CI) 50 to 66 per cent) of respondents in these hotels believed their health was being adversely affected by other people's smoke in the hotel. Seventy per cent (CI 62 to 78 per cent), including half the smokers, were in favour of restriction of smoking in the hotels. Most preferred the establishment of smoke-free areas to the introduction of total smoking bans in hotels. The failure of hotels to regulate smoking suggests that a legislative approach is required. The case for legislation would be strengthened by a larger study elsewhere in Australia.

Characterization of a unique population of Fusarium oxysporum f.sp. cubense causing Fusarium wilt in Cavendish bananas at Carnarvon, Western Australia

A unique population of Fusarium oxysporum f. sp. cubense affecting Cavendish cv. Williams banana plants was characterized using vegetative compatibility, volatile production, RAPD-PCR analysis, pectic enzyme production and pathogenicity. The isolates were more like race 1 isolates than race 4 isolates, although they were capable of attacking Cavendish clones. The Carnarvon isolates did not belong to any of the vegetative compatibility groups (VCGs) known to occur in Australia or overseas; they belonged in the 'inodoraturn' volatile group; they had 29% genetic similarity to race 4 isolates and 76% similarity to race 1 isolates based on RAPD-PCR banding patterns; they belonged in the same pectic zymogram group as race 1 isolates and were virulent on 3-month-old Cavendish cv. Williams, Gros Michel and Pisang Gajih Merah plants in glasshouse tests.

DNA fingerprinting using arbitrary primer technology (APT): a tool or a torment

A recent variation of the PCR has allowed DNA fingerprints to be obtained independently of prior sequence information and with unparalleled ease. Several approaches, conveniently grouped under the general term of arbitrary primer technology (APT), include the popular RAPD, DAF, and AP-PCR methods. A great deal of attention has been focussed on these methods and questions have arisen regarding reproducibility, DNA fingerprint resolution, and even the future of the technology itself. Here we discuss these issues and examine some of the unique properties of DNA amplification using a single short arbitrary primer.

Measurement of inspiratory muscle performance with incremental threshold loading: a comparison of two techniques

BACKGROUND

Incremental threshold loading (ITL) is a test of inspiratory muscle performance which is usually performed by breathing through a weighted inspiratory plunger, the load on the inspiratory muscles being increased by externally adding weights to the intake valve. This is not a true threshold device and may be inaccurate. This method was compared with a true threshold device consisting of a solenoid valve which only opens to supply air at a predetermined negative mouth pressure.

METHODS

Six naive, normal subjects (three men and three women) aged 22-24 years underwent three tests using each system. The inspiratory loads were increased every minute by equivalent amounts, -10 cm H2O with the solenoid valve and by 50 g with the weighted plunger, until the subjects could not inspire or sustain inspiration for a full minute. Six experienced subjects (four men and two women) aged 23-41 years were subsequently randomised to perform ITL with the solenoid valve, twice with the breathing pattern fixed and twice free.

RESULTS

The solenoid valve generated a more accurate mouth pressure response and was less variable at higher loads than the weighted plunger. The work performed (expressed as the pressure-time product) was less with the solenoid valve but was more reproducible. ITL with the solenoid valve was not influenced by controlling the breathing pattern of the subjects.

CONCLUSIONS

The solenoid valve has several features that make it superior to the weighted plunger as a device for ITL. It generates a more accurate mouth pressure response which is less variable at higher loads. Increases in load are smoother and quicker to introduce. ITL with the solenoid valve is not influenced by varying breathing patterns and does not require any external regulation.

Prevention of tuberculosis in children: missed opportunities

We conducted an eight-year prospective investigation in Tennessee of all cases of tuberculosis (TB) reported statewide in children younger than 15 years of age. Of the 109 verified childhood cases reported from 1981 to 1988, at least 23 (21%) were preventable. Eleven children developed the disease while they were under surveillance but were not receiving preventive therapy, nine cases resulted from failure of health care providers to conduct timely contact interviews/investigations, and three were due to other reasons. Improved surveillance, increased use of preventive therapy, and ensured compliance will contribute significantly to the elimination of tuberculosis in children at high risk of developing the disease.

Effect of methacholine induced bronchoconstriction on the spectral characteristics of breath sounds in asthma

BACKGROUND

Analysis of breath sounds by digital techniques offers an attractive non-invasive method of monitoring changes in airway calibre. Asthmatic breath sounds have been analysed and related to changes in forced expiratory volume in one second (FEV1).

METHODS

Bronchoconstriction was induced with methacholine in six asthmatic subjects on two occasions and changes in FEV1 and breath sound spectra were measured.

RESULTS

Audible wheeze appeared after a mean (SE) fall in FEV1 of 35% (6.3%) but the level was not reproducible within patients. The mean and median frequency of the spectra of breath sounds correlated with the percentage of predicted FEV1 (r = -0.5 and -0.6 respectively; p < 0.001). Inclusion of the quartile frequencies in a stepwise multiple regression reduced the residual variance by a further 9%.

CONCLUSION

Detecting changes in airway calibre by this method of sound analysis so far produces qualitative data only and will not yield quantitative data in individual patients.

The management of impotence in diabetic men by vacuum tumescence therapy

The treatment of impotence in diabetic men with vacuum tumescence therapy was studied in a specialist clinic. Of 54 diabetic men referred with impotence, seven declined treatment, three chose self-injection with papaverine, and 44 chose vacuum therapy. Patients underwent autonomic function testing (heart rate response to respiration), measurement of penile blood flow (duplex Doppler scanning), and estimation of serum prolactin and testosterone levels. After 2 months, 33 men (75%) were able to have satisfactory intercourse using vacuum therapy. Three others could produce a satisfactory erection with vacuum therapy but their partners found it unacceptable. Eight men (18%) were unable to have satisfactory intercourse; six of these were later treated by self-injection. The median frequency of use of vacuum therapy was 5.5 (1-26) times a month. Outcome was independent of penile blood flow, autonomic function or endocrine status. Impotent diabetic men should be given counselling and offered a choice of the available treatments. Vacuum tumescence therapy is an effective and simple treatment which requires little investigation.

99mTc radioimmunoscintigraphy of colorectal cancer

The monoclonal antibody PR1A3 against a normal colonic columnar cell surface antigen has been labelled with 99mTc and used for imaging colorectal cancer. High uptake in undifferentiated cancer is seen. The tumour to mucosa ratio was up to 63:1 and the percentage of the injected activity in the tumour up to 1.7 X 10(-2%)g-1. As 99mTc is continuously available in a Nuclear Medicine Department, on receipt of a request the study may be completed within 24 h enabling radioimmunoscintigraphy to be used routinely in the management of patients with colorectal cancer.

Modification of deoxyribonucleic acid-thyroid hormone receptor interaction by histones

The effects of histones on receptor-DNA interaction were examined using an in vitro DNA-cellulose-binding assay of [125I]T3 receptor. H1 histones bound to DNA-cellulose strongly inhibited binding of receptor to DNA-cellulose. DNA-cellulose column chromatography showed that 80% of T3-binding activity attached to DNA-cellulose could be eluted using 1 mg H1 histone/ml at low ionic strength. The potent inhibitory activity of H1 histones on receptor-DNA binding was reversed by removal of H1 histones from DNA-cellulose or by removal of H1 histones from receptor. The interaction was specific for the DNA-binding activity of receptor, since H1 histones inhibit neither T3-binding activity nor core histone-binding activity of receptor. In contrast, low concentrations of core histones enhanced binding of T3 receptor to DNA-cellulose. This effect was also seen when DNA-cellulose was treated with core histones and then deprived of free core histones. The enhancement was reversed by removal of core histones bound to DNA-cellulose. A tryptic fragment of the receptor, which lost DNA-binding activity but retained hormone and core histone-binding activities, was capable of binding to DNA-cellulose in the presence of core histones. These data suggest that enhanced binding of receptor to DNA-cellulose by core histones is mediated through the core histone-binding activity of receptor. A heat-labile protein factor in nuclear extracts (possibly receptor itself) also enhanced receptor binding to DNA-cellulose. Our data suggest important roles of histones in the organization of nuclear thyroid hormone receptors in chromatin. Since H1 histone participates in condensation of chromatin and is enriched in transcriptionally inactive chromatin, inhibition of DNA-binding activity of receptor by H1 histone bound to DNA could explain the preferential binding of nuclear thyroid hormone receptor to transcriptionally active chromatin.

A technique for the long term measurement of intra-compartmental pressure in the lower leg

The early diagnosis of an acute compartmental pressure syndrome is often difficult, but can be facilitated by long term, up to several days, measurement of intra-compartmental pressures. A measuring system has been developed, together with its associated surgical and operational procedures, which may be applied in a variety of situations, including an immobile patient or a patient mobilized following surgery. If the technique is adopted as soon as the patient enters hospital, or immediately postoperatively, an acute compartmental syndrome may be recognized early and measures taken to alleviate its consequences.

The pastoral challenge of an abusive situation

This paper explores a ministerial response to congregants who have abused or neglected their child. I begin by distinguishing the three major secular responses to this kind of family problem: casework, counseling, and therapy, and go on to note how all of the above are limited in their effectiveness by the objective, causal, explanatory framework within which they operate. I suggest that a pastor can take the same family facts and help those involved to understand and respond to them concretely as they are experienced. The paper concludes with an exploration of this alternative approach within a religious vocabulary of prayer and increased inwardness.