Reassessing the principles of electrical stimulation.

The mechanisms by which electrical stimulation (ES) of carcasses can be used to modulate meat quality are reviewed. Evidence to support an effect of ES on tenderness (and other meat quality attributes) based solely on changes in the pH/temperature profile within carcass muscles are presented. The interactions between electrical parameters and the contraction responses of carcass muscles are described to provide generalised principles to guide the design of electrical stimulation technology. The commercial risks to meat quality of inappropriate use of electrical stimulation, particularly excessive stimulation to produce PSE-like conditions, are considered.

Integrated technologies to enhance meat quality - An Australasian perspective.

Ensuring meat quality attributes meet the requirements of the diverse range of markets is a critical component for the continued success of the New Zealand and Australian meat industries. Developing cost-effective and flexible technologies to help meet this requirement is a central objective of a current Meat and Wool New Zealand and Meat and Livestock Australia funded programme. This initiative was developed three years ago; it is a collaborative programme that involves meat scientists, electrical engineers and commercial meat processors. To ensure this programme successfully delivers technologies and knowledge to the Australasian meat industry, the following strategies have been developed: measurement of meat quality attributes 'on-line' during processing; development of 'expert systems' that can integrate and interpret on-line measurements and development of quality-related feedback systems from the market that can be fed back to producers; and, development of methods to manipulate structural and biochemical events in meat to create new commercial opportunities for both producers and processors. This paper gives an overview of some of the new technologies that have developed from this programme that are being used commercially or, are undergoing the final stages of commercial validation.

Sexually transmitted diseases: a survey of case management in Malawi.

A national survey of sexually transmitted disease (STD) case management was carried out at 39 health care facilities in Malawi in 1994. Fifty-four health care providers were observed managing 150 patients presenting with selected STD syndromes and 103 providers were interviewed. STD case management was assessed by calculation of WHO/GPA prevention indicators (PIs) from observation data. The overall rate for PI-6, which measures correct assessment and treatment of STD patients was 11% (81% for history taking, 46% in physical examination, and 13% correct antibiotic treatment according to national guidelines). The score for PI-7, which measures overall patient counselling was 29% (65% for partner notification and 40% for condom advice). Although Haemophilus ducreyi is at least as common as Treponema pallidum as the causative agent for genital ulcers, only 16% of patients with genital ulcers were treated effectively for chancroid vs 56% for syphilis. Female patients received less comprehensive care than male STD patients. Only 20% of STD patients were offered condoms. Overall, the survey results support the policy decision to adopt syndromic management of STDs, and provide baseline information for planning and evaluation of a national control programme.

Investigation into the principal determinants of effective captive bolt stunning of sheep.

In order to identify the physical component of captive bolt stunning responsible for abolishing visual evoked responses, experimental forms of captive bolt stunning were carried out on anaesthetised sheep. Supporting the captive bolt pistol away from the skull to permit limited penetration of the brain was found to be as effective as conventional shooting methods at abolishing visual evoked responses (responses were lost in all animals). Whereas, manual insertion of the bolt through a trephined hole or shooting through a trephined hole was significantly less effective (respectively, one of eight and four of eight animals lost responses). It is concluded that the impact of the bolt with the cranium is the principal determinant of effective stunning, rather than the penetration of the bolt into the brain tissues.

Concussive methods of pre-slaughter stunning in sheep: effects of captive bolt stunning in the poll position on brain function.

The effectiveness of captive bolt stunning in the poll position was evaluated in eight anaesthetised sheep. Brain function following shooting was assessed using cortical visual evoked responses (VERs). Immediately following shooting, VERs were abolished in all sheep. However, in five of the sheep, VERs gradually recovered; responses became evident in these animals in a mean (+/- SE) time of 50 +/- 16.7 seconds. These results suggest that captive bolt shooting in the poll position can be associated with rapid recovery of brain function. Because such recovery could be associated with return of sensibility, shooting in the poll position should only be used when essential (ie, in horned animals) and then always followed promptly by sticking.

Concussive methods of pre-slaughter stunning in sheep: assessment of brain function using cortical evoked responses.

Averaged cortical evoked responses were used to evaluate brain function in anaesthetised sheep. Effects on both evoked somatosensory responses (SERs) and visual evoked responses (VERs) were examined. Following capitive bolt stunning, SERs and VERs were abolished instantaneously and did not reappear for the duration of the experiment. Similar results were found when animals were shot while conscious. It was concluded that captive bolt stunning in sheep produces an immediate, profound and long lasting brain failure and is therefore an effective preslaughter stunning method.

The effects of the ultimate pH of meat on tenderness changes during ageing.

A range of ultimate pH (pH(u)) values, from 5.4 to 7.2, was produced in the m. longissimus thoracicum et lumborum (LD) of 55 sheep by subcutaneous injections of adrenaline, or by injection and subsequent exercise. The rate constant of ageing for each of 47 animals was calculated from shear force measurements, taken at intervals for up to 5 days from the LD held at 12 dgC. The relationship between the ageing rate and pH(u) could be adequately described by the equation rate constant (k) = 4.109 - 1.349(pH) + 0.1111(pH)(2); r(2) = 0.707, with a minimum rate constant at pH 6.07. The loin muscles from eight carcasses were selected to determine the effects of ultimate pH on the initial, unaged toughness value. Calpain activity was inhibited by intramuscular injection of ZnCl(2) dissolved in saline, and the muscles were aged at 10-12 °C on the carcass for up to 6 days. At all values of pH(u) (5.4-6.7), tenderness as measured by shear force were equivalent, from which it was concluded that the initial toughness of unaged lamb was not affected by pH(u). In the contralateral, untreated muscle, ageing was measured using both shear force measurement and changes in the myofibrillar fragmentation index (MFI). After 1 day, the intermediate pH range (5.8-6.2) has the highest shear force and the lowest fragmentation index value. However, in contrast to the shear force values, the ultimate MFI value in aged muscle was lowest in the high pH(u) range (6.4-6.7; minimum value at 6.4). The highest fragmentation values were found at the low pH(u) range. These observations suggest that pH(u)-related tenderness differences in meat result from different rates of ageing in the post rigor period, and therefore that these differences disappear following a sufficient ageing period. The slowest rate of tenderization measured on cooked meat was observed at pH(u) values around 6.07, but the least fragmentation of raw meat was observed at pH(u) values around 6.4, a difference of almost 0.33 pH unit.

Cortical function in cattle during slaughter: conventional captive bolt stunning followed by exsanguination compared with shechita slaughter.

Brain function was examined in adult cattle after conventional captive bolt stunning or shechita slaughter, using eight animals in each treatment. The times to loss of evoked responses (visual and somatosensory) and spontaneous activity in the electro-corticogram were used to determine the onset of brain failure. Captive bolt stunning followed by sticking one minute later resulted in immediate and irreversible loss of evoked responses after the stun. Spontaneous cortical activity was lost before sticking in three animals, and in an average of 10 seconds after sticking in the remaining five animals. The duration of brain function after shechita was very variable, and particularly contrasted with captive bolt stunning with respect to the effects on evoked responses. These were lost between 20 and 126 seconds (means of 77 seconds for somatosensory and 55 seconds for visual evoked responses) and spontaneous activity was lost between 19 and 113 seconds (mean 75 seconds) after slaughter.

Modelling muscle energy-metabolism in anaerobic muscle.

A mathematical model of anaerobic muscle energy-metabolism was developed to predict pH and the concentrations of nine muscle metabolites over time. Phosphorous-31 Nuclear Magnetic Resonance was used to measure time-course data for some phosphate metabolites and pH in anoxic M. semitendinosus taken from three slaughtered sheep. Muscles were held at 35 degrees C during the experiment. Measurement commenced 25 min post mortem and concluded before rigor mortis. The model was fitted to these data within experimental error, by simultaneously varying model parameter values and initial substrate concentrations. The model was used to simulate the period from death until metabolic activity ceased, in order to predict the different stages of metabolic response to anoxia. The model suggested that alkalinisation would occur in all three muscles in the first few minutes after the onset of anoxia, followed by a steady decline in pH. For two of the muscles this decline continued until rigor, with final pH values of 5.60 and 6.07. For the other muscle, pH reached a low of 5.60 near rigor but then increased to a final value of 5.73. A rise in pH after rigor has been observed but not previously explained in the literature. The modelling results suggest it was caused by the alkalising effect of adenosine monophosphate deamination being greater at low pH than the acidifying effect of inosine monophosphate dephosphorylation.

Electroencephalographic studies on the nape shooting of sheep.

The implications of shooting animals in the area of the occipito-atlantal junction was evaluated in three sheep by recording changes in the EEG activity. In one sheep, a shot which entered the occipito-atlantal junction and fractured the first cervical vertebra failed to produce insensibility. In contrast, a shot in another sheep which struck the occipital condyles of the skull resulted in loss of cortical evoked responses, the presence of high amplitude low frequency activity and ultimately all loss of brain activity. These results provide evidence that shooting through the vertebral column does not necessarily transmit sufficient percussive forces to higher brain regions to produce immediate insensibility. This has important implications for the humane destruction of animals, particularly, as in the case of cetaceans, where the occipito-atlantal junction or a high neck position is a recommended target area.

Photograms for microbiological assays.

The use of photograms provides a permanent record of microbiological assays in which diffusion of a substance in agar is measured. The accuracy of this procedure is comparable to direct measurement. This technique is inexpensive, does not require special photographic equipment, and is applicable to many tests commonly employed in clinical microbiology and immunology laboratories.

Prevalence and duration of insensibility following electrical stunning in calves.

Sixty-one calves were electrically stunned with 100-250 V currents (103-1806 mA) and the prevalence and duration of insensibility was assessed from their physical behaviour, the presence of epileptiform activity in their electrocorticograms, and the absence of visual evoked responses in their electrocorticograms. A current applied at 100 V across the head for 3 s failed to induce insensibility in all cases. Currents at 150-250 V induced insensibility in all calves and the shortest duration of insensibility was 44 s. It is recommended that a 150-200 V current would be appropriate for commercial use.

Contraceptive methods and the transmission of HIV: implications for family planning.

Heterosexual transmission is the predominant mode of spread of the Human Immunodeficiency Virus (HIV) in most of the world. Whether the use of hormonal contraceptives, IUDs and spermicides is associated with an increased or decreased risk for HIV acquisition remains controversial. Several mechanisms whereby contraceptive methods may influence the transmission of HIV have been proposed. As contraceptive use increases among women of reproductive age, the group most vulnerable to HIV infection, any associations between contraceptive method and HIV risk become even more important. The available studies of these associations are predominantly cross-sectional and give conflicting results. We review the published evidence for associations between HIV and individual contraceptive methods. At this time no definitive conclusions regarding these associations can be drawn. Further research, especially prospective epidemiological studies and basic biological research on mechanisms of heterosexual transmission and the effect of contraceptives on these mechanisms, is urgently needed.

PIP: The current literature on the transmission of HIV and the use of oral contraceptives (OCs), injectables, IUDs, spermicides, and the female condom was reviewed. Some of the methodological difficulties involved study design (observational studies, cross-sectional, case control, and prospective studies) and confounding factors (age, marital status, sexual partners). The impact of OC use on HIV transmission is likely to be minor, but some factors contributing to transmission include cervical ectropion, which enhances HIV transmission. Nevertheless, in a 1990 Nairobi study of 4404 women no such association was detected. Sexually transmitted diseases (STDs) have been risk factors in HIV transmission. OCs that decrease irregular bleeding may protect against HIV. Progestin-only pills could act on the risk of HIV transmission by thickening cervical mucus and thinning the vaginal epithelial layer. 21 epidemiological studies were identified on the use of OCs and transmission. Except for a 1990 Nairobi study among prostitutes none of them reported a significant association between OC use and HIV seropositivity. Injectables (Depo Provera) could theoretically increase HIV transmission, but no such conclusive evidence has surfaced. Increased risk of transmission or seropositivity has been reported with IUD use, but this needs confirmation by prospective studies. Among spermicides the nonoxynol-9 sponge slightly increased HIV seroconversion in 139 sex workers in Nairobi in a 1992 study. However, this trial was contradicted by other prospective studies conducted in Cameroon and Zambia. Nonoxynol-9 kills HIV but also damages the cervical and vaginal mucosa enhancing HIV transmission. In 1992 in vitro activity in 26 out of 131 other spermicides screened inhibited HIV. The female condom was tested in 104 women in a 1993 prospective study in the US and no recurrences of trichomonas occurred in 20 women who used it consistently over a 6-week period. More prospective epidemiological studies are needed, and the risk of HIV infection should be part of counseling on contraceptives.

Quality of case management of sexually transmitted diseases: comparison of the methods for assessing the performance of providers.

This article examines the reliability and validity of direct observation of patient-provider encounters, interviews with providers, and use of patients simulating sexually transmitted diseases (STD) as methods for assessing the quality of STD case management in developing countries. Data were collected during an STD health facility survey in Malawi; the performance of 49 providers was observed, and the providers were also interviewed; 20 of them were visited by a simulated patient complaining of urethral discharge. Agreement (based on the kappa statistic) was generally poor between direct observation and provider-interview data, and also between direct observation and simulated-patient data. In contrast, percentage agreements between direct observation and simulated-patient data were often high. Multiple observations on providers indicated that a provider's behaviour is not consistent across several patients. Simulated-patient data are probably the best in reflecting normal performance, but their feasibility for routine quality assessment is limited because the provider's behaviour is not consistent and would require multiple data points. Direct observation data are the best option for assessing quality if the results are assumed to reflect better than normal levels of quality of care. Data from interviews with providers should be viewed with caution, because they may reflect provider knowledge and not necessarily performance.

PIP: The quality of health care delivery in developing countries has been assessed by many studies using the following methods: direct observation of patient-provider encounters, review of records, exit interviews with clients, interviews with providers, and inventories of facilities, drugs, and supplies. This paper assesses the reliability and validity of the following methods used in a nationwide survey of STD case management conducted in health facilities in Malawi in 1994: the direct observation of provider-patient encounters, interviews with providers, and the use of people who pretend to be patients. The performance of 49 providers was observed. All of the providers were also interviewed and 20 were visited by a simulated patient complaining of urethral discharge. Multiple observations of providers indicated that any given provider does not behave in the same manner with all patients. Simulated-patient data can probably give the most accurate view of a provider's typical performance, but the approach has only limited use in routine quality assessment because the inconsistent nature of providers' behavior would require multiple data points per provider. Direct observation data are the best when measuring quality if the results are thought to be of higher quality than normal care. Data from interviews with providers should be carefully interpreted since they may reflect only provider knowledge and not his or her actual performance.

A cost comparison of approaches to sexually transmitted disease treatment in Malawi.

Since syndromic management of STDs requires treatment with at least two antibiotics per patient, one of the concerns raised by adoption of the syndromic approach is the cost of drugs, especially for developing countries with limited drug budgets. The objective of the current study is to compare the cost-effectiveness of syndromic management to current national practice for the management of STDs in Malawi. The actual cost of observed antibiotic treatment for 144 patients receiving same day treatment for two STD syndromes in Malawi was determined using prices from the Malawi government supply catalogue. This was then compared to the calculated cost of treatment had the same patients been managed syndromically according to national guidelines. The cost of drug treatment under current practice was similar to the cost of syndromic treatment. However, at least one-third of observed patients did not receive effective treatment for either likely cause of their STD syndrome and wastage accounted for 54% of total observed drug cost. Overall, syndromic management of STDs in Malawi would result in more effective treatment of STDs at no additional cost. Since the indirect costs of low treatment efficacy were not taken into account in this analysis, a net saving is likely to be realized with the adoption of syndromic management.

Risk factors for gonorrhoea, syphilis, and trichomonas infections among women attending family planning clinics in Nairobi, Kenya.

OBJECTIVE: To identify the risk factors for gonorrhoea, syphilis, and trichomonas infections among low risk women in Nairobi, Kenya. METHOD: In a cross-sectional study, 4,404 women attending two peri-urban family planning clinics between 1989 and 1991 were interviewed using a structured questionnaire and examined for signs of sexually transmitted disease (STD) infection. Cervical cultures for gonorrhoea, PAP smear (including microscopy for trichomonas), RPR and HIV testing were done. RESULTS: Positive cervical cultures for gonorrhoea were found in 3.2% of women, positive syphilis serology in 1.9%, and positive trichomonas microscopy in 5.2%. Genital ulcers were found in 1.9% of women. Although unmarried status and reporting more than one sex partner in the previous year were both significantly associated with each disease in the crude analysis, these associations were attenuated after controlling for each other and for other risk factors. The population attributable risks (PARs) for these factors were low (7-16%) owing to the high proportion of cases who were married and monogamous. The majority of women with microbiological evidence of infection had normal pelvic examinations. Clinical diagnostic algorithms for STDs in this population had a low sensitivity and positive predictive value. Nevertheless, a strong association between HIV seropositivity and STDs was observed. CONCLUSION: The low population attributable risks found in this study suggest that behaviour change messages directed to women, particularly if they are married have a low potential for preventing STDs. The poor performance of clinical diagnostic algorithms illustrates the desirability of testing these algorithms in a variety of populations and reinforces the need for low-cost methods of microbiologic diagnosis if populations with relatively low prevalences of these infections are to be included in programmes to diagnose and treat STDs.

PIP: Between October 1989 and May 1991 in Kenya, clinicians interviewed and took cervical cultures from 4404 women attending 2 periurban family planning clinics in predominantly lower socioeconomic areas of Nairobi to determine risk factors for sexually transmitted diseases (STDs) among low-risk women. Most women were married and/or had only one sexual partner in the past year. The STD prevalence rates were 3.2% for gonorrhea, 1.9% for syphilis, 5.2% for trichomonas, and 4.9% for HIV infection. The crude analysis showed that unmarried status and at least 2 sexual partners in the last year were significantly correlated with each STD. When the researchers controlled for each disease and for other risk factors, however, neither unmarried status nor at least 2 sexual partners were associated with the STDs. The population attributable risks (PARs) for unmarried women were 9.7% for gonorrhea, 9.1% for syphilis, and 15.9% for trichomonas. The PARs for more than 1 sexual partner were 7.7%, 7.2%, and 7.4%, respectively. These PARs were relatively low due to the considerable proportion of married and monogamous women in the sample. HIV seropositivity was the most significant predictor of gonorrhea, syphilis, and trichomonas infections (odds ratio = 1.9-3.4). The pelvic examinations of most women who had microbiological evidence of an STD were normal. The clinical diagnostic algorithms for STDs in the study used the most readily accessible and significant risk factors and physical examination findings. They had a relatively high specificity (76 - 99%) but low sensitivity ( 1 - 38%). These findings showed that none of the risk factors or the physical examination could be sufficiently used to predict an STD diagnosis. They also indicate the need for inexpensive diagnostic tests to identify and treat women at a relatively low risk of STDs in family planning and other clinics.

Development of an antimicrobial susceptibility surveillance system for Neisseria gonorrhoeae in Malawi: comparison of methods.

Susceptibility of Neisseria gonorrhoeae to gentamicin, the primary treatment for gonorrhea in Malawi since 1993, was determined by using agar dilution MICs, E-test MICs, disc diffusion, and clinical cure rate. Agar dilution MICs were slightly higher in 1996 than in 1993 isolates, with a concomitant drop in the clinical cure rate. E-test MICs were substantially lower than agar dilution determinations, with only 77.4% within 1 log2 concentration.

PIP: Gentamicin (240 mg single intramuscular dose) was adopted in 1993 as the treatment of choice for gonorrhea in Malawi, following findings of high-level gonococcal resistance to penicillin, tetracycline, and streptomycin. This study sought to assess the clinical efficacy of gentamicin in the treatment of Neisseria gonorrhoeae 2 years after the onset of its widespread use and to evaluate the potential roles of the disc diffusion and E test in the development of a surveillance system for monitoring antimicrobial susceptibility. 206 consecutive men presenting to a sexually transmitted disease clinic in Lilongwe in 1996 and 198 urethritis patients treated at a hospital in Blantyre during 1992-93 were enrolled. The clinical cure rate for gentamicin treatment of gonorrhea was 91.8% in 1996 compared to 95.0% in 1993. The proportion of highly susceptible isolates declined from 17.2% in 1993 to 9.5% in 1996, but the majority of isolates remained in the moderately susceptible category. The E test yielded substantially lower minimum inhibitory concentrations (MICs) than the standard agar dilution assay, with only 77.4% within 1 log2 concentration. Disc diffusion was not helpful in determining the efficacy of gentamicin, since there was little difference in the range of disc diameters at different MICs as determined by agar dilution. Establishment of an MIC that clearly shows resistance to gentamicin was not possible. These findings suggest that the agar dilution assay remains the method of choice for MIC determination, although the less expensive E test may be capable of monitoring antibiotic efficacy under field conditions.

Prevalence of hepatitis C infection in Malawi and lack of association with sexually transmitted diseases.

To investigate the role of sexual transmission for Hepatitis C virus (HCV) we studied its prevalence in sub-Saharan Africa where sexually transmitted diseases (STDs) are prevalent. Overall, HCV prevalence was 3.9% and similar in 206 STD patients, 127 dermatology patients, and 100 blood donors. No association with HIV or syphilis was observed. Despite high prevalence of STDs, sexual transmission does not appear to significantly contribute to HCV transmission in Malawi.