Causally Probing the Role of the Hippocampus in Fear Discrimination: A Precision Functional Mapping-Guided, Transcranial Magnetic Stimulation Study in Participants With Posttraumatic Stress Symptoms

Background

Fear overgeneralization is a promising pathogenic mechanism of clinical anxiety. A dominant model posits that hippocampal pattern separation failures drive overgeneralization. Hippocampal network-targeted transcranial magnetic stimulation (HNT-TMS) has been shown to strengthen hippocampal-dependent learning/memory processes. However, no study has examined whether HNT-TMS can alter fear learning/memory.

Methods

Continuous theta burst stimulation was delivered to individualized left posterior parietal stimulation sites derived via seed-based connectivity, precision functional mapping, and electric field modeling methods. A vertex control site was also stimulated in a within-participant, randomized controlled design. Continuous theta burst stimulation was delivered prior to 2 visual discrimination tasks (1 fear based, 1 neutral). Multilevel models were used to model and test data. Participants were undergraduates with posttraumatic stress symptoms (final n = 25).

Results

Main analyses did not indicate that HNT-TMS strengthened discrimination. However, multilevel interaction analyses revealed that HNT-TMS strengthened fear discrimination in participants with lower fear sensitization (indexed by responses to a control stimulus with no similarity to the conditioned fear cue) across multiple indices (anxiety ratings: β = 0.10, 95% CI, 0.04 to 0.17, p = .001; risk ratings: β = 0.07, 95% CI, 0.00 to 0.13, p = .037).

Conclusions

Overgeneralization is an associative process that reflects deficient discrimination of the fear cue from similar cues. In contrast, sensitization reflects nonassociative responding unrelated to fear cue similarity. Our results suggest that HNT-TMS may selectively sharpen fear discrimination when associative response patterns, which putatively implicate the hippocampus, are more strongly engaged.

A data-driven model of brain volume changes in progressive supranuclear palsy

The most common clinical phenotype of progressive supranuclear palsy is Richardson syndrome, characterized by levodopa unresponsive symmetric parkinsonism, with a vertical supranuclear gaze palsy, early falls and cognitive impairment. There is currently no detailed understanding of the full sequence of disease pathophysiology in progressive supranuclear palsy. Determining the sequence of brain atrophy in progressive supranuclear palsy could provide important insights into the mechanisms of disease progression, as well as guide patient stratification and monitoring for clinical trials. We used a probabilistic event-based model applied to cross-sectional structural MRI scans in a large international cohort, to determine the sequence of brain atrophy in clinically diagnosed progressive supranuclear palsy Richardson syndrome. A total of 341 people with Richardson syndrome (of whom 255 had 12-month follow-up imaging) and 260 controls were included in the study. We used a combination of 12-month follow-up MRI scans, and a validated clinical rating score (progressive supranuclear palsy rating scale) to demonstrate the longitudinal consistency and utility of the event-based model's staging system. The event-based model estimated that the earliest atrophy occurs in the brainstem and subcortical regions followed by progression caudally into the superior cerebellar peduncle and deep cerebellar nuclei, and rostrally to the cortex. The sequence of cortical atrophy progresses in an anterior to posterior direction, beginning in the insula and then the frontal lobe before spreading to the temporal, parietal and finally the occipital lobe. This in vivo ordering accords with the post-mortem neuropathological staging of progressive supranuclear palsy and was robust under cross-validation. Using longitudinal information from 12-month follow-up scans, we demonstrate that subjects consistently move to later stages over this time interval, supporting the validity of the model. In addition, both clinical severity (progressive supranuclear palsy rating scale) and disease duration were significantly correlated with the predicted subject event-based model stage (P < 0.01). Our results provide new insights into the sequence of atrophy progression in progressive supranuclear palsy and offer potential utility to stratify people with this disease on entry into clinical trials based on disease stage, as well as track disease progression.

The late-onset dilated cardiomyopathy

Background

Dilated Cardiomyopathy (DCM) represents a specific subgroup of non-ischemic cardiomyopathies. Little is known about the genotypic characterization of dilated cardiomyopathy (DCM) patients diagnosed over 60 years of age.

Aim

To investigate prevalence, characterization and prognostic impact of the genetic background of late-onset DCM patients.

Methods

We analyzed a study population of 566 DCM patients from two international referral centers. Genetic background was analyzed and patients were grouped into typical-onset DCM (&lt;60 years of age at diagnosis) or late-onset DCM (&gt;60 years of age at diagnosis).

Results

Approximately 12% of patients (n=70) had late-onset DCM and female sex was significantly more frequent in the late-onset DCM cohort (p&lt;0.001). Diagnostic yield of genetic testing was comparable between typical- and late-onset DCM (53% vs 50%, respectively p=0.438) whereas the prevalence of Titin gene truncation variants (TTNtv) was higher in the late-onset DCM group compared to the younger cohort (23% vs 13% respectively; p&lt;0.05). Notably, patients with late-onset genetic DCM had comparable long-term outcomes to those with typical-onset DCM.

Conclusions

Late-onset DCM patients have nearly double the rate of TTNtv mutations and are more likely to be female compared to younger DCM patients. These observed differences in mutational makeup and sex may reveal insights into age and sex dependent mechanisms for TTNtv and should prompt further study. Notably, the increased prevalence of TTNtv and female sex did not translate into noticeable differences in rates of measurable cardiac events.

Funding Acknowledgement

Type of funding source: None

Predictive Model of Listeria Monocytogenes’ Growth Rate Under Different Temperatures and Acids

A response surface model of Listeria monocytogenes’ growth rate was built in this study under different temperatures (10 °C, 15 °C, 20 °C, 25 °C and 30 °C) and acid concentrations: citric acid (0–0.4%) and ascorbic acid (0–0.4%); two ingredients which are often used in the food industry as preservatives. Mathematical validation was performed with additional samples at different conditions within the range of the model, obtaining acceptable values of root mean square error (0.0466), standard error of prediction (18.84%), bias factor (1.05) and accuracy factor (1.16). The inhibitory effect on growth was more effective with citric acid than ascorbic acid, possibly due to the major dissociation of citric acid occurring inside microbial cells. The different conditions considered in the model will potentially allow L. monocytogenes’ response to be predicted in foods having a similar composition to the chemical and physical factors set out in this paper.

A mathematical risk model for Escherichia coli O157:H7 cross-contamination of lettuce during processing

A stochastic simulation modelling approach was taken to determine the extent of Escherichia coli O157:H7 contamination in fresh-cut bagged lettuce leaving the processing plant. A probabilistic model was constructed in Excel to account for E. coli O157:H7 cross contamination when contaminated lettuce enters the processing line. Simulation of the model was performed using @Risk Palisade© Software, providing an estimate of concentration and prevalence in the final bags of product. Three different scenarios, named S1, S2, and S3, were considered to represent the initial concentration on the contaminated batch entering the processing line which corresponded to 0.01, 1 and 100 cfu/g, respectively. The model was satisfactorily validated based on Standard Error of Prediction (SEP), which ranged from 0.00-35%. ANOVA analysis performed on simulated data revealed that the initial concentration in the contaminated batch (i.e., S1, S2, and S3) did not influence significantly (p=0.4) the E. coli O157:H7 levels in bags derived from cross contamination. In addition, significantly different (p<0.001) prevalence was observed at the different levels simulated (S1; S2 and S3). At the lowest contamination level (0.01 cfu/g), bags were cross-contaminated sporadically, resulting in very low E. coli O157:H7 populations (mean: ≤2 cfu/bag) and prevalence levels (<1%). In contrast, higher average prevalence levels were obtained for S2 and S3 corresponding to 3.05 and 13.39%, respectively. Furthermore, the impact of different interventions on E. coli O157:H7 cross-contamination (e.g., pathogen testing, chlorination, irradiation, and cleaning and disinfection procedures) was evaluated. Model showed that the pathogen was able to survive and be present in the final bags in all simulated interventions scenarios although irradiation (0.5 KGy) was a more effective decontamination step in reducing prevalence than chlorination or pathogen testing under the same simulated conditions.

Exploring historical Canadian foodborne outbreak data sets for human illness attribution

Human illness attribution has been recently recognized as an important tool to better inform food safety decisions. Analysis of outbreak data sets has been used for that purpose. This study was conducted to explore the usefulness of three comprehensive Canadian foodborne outbreak data sets covering 30 years for estimating food attribution in cases of gastrointestinal illness, providing Canadian food attribution estimates from a historical perspective. Information concerning the microbiological etiology and food vehicles recorded for each outbreak was standardized between the data sets. The agent-food vehicle combinations were described and analyzed for changes over time by using multiple correspondence analysis. Overall, 6,908 foodborne outbreaks were available for three decades (1976 through 2005), but the agent and the food vehicle were identified in only 2,107 of these outbreaks. Differences between the data sets were found in the distribution of the cause, the vehicle, and the location or size of the outbreaks. Multiple correspondence analysis revealed an association between Clostridium botulinum and wild meat and between C. botulinum and seafood. This analysis also highlighted changes in food attribution over time and generated the most up-to-date food attribution values for salmonellosis (29% of cases associated with produce, 15% with poultry, and 15% with meat other than poultry, pork, and beef), campylobacteriosis (56% of cases associated with poultry and 22% with dairy products other than fluid milk), and Escherichia coli infection (37% of cases associated with beef, 23% with cooked multi-ingredient dishes, and 11% with meat other than beef, poultry, and pork). Because of the inherent limitations of this approach, only the main findings should be considered for policy making. The use of other human illness attribution approaches may provide further clarification.

Attitudes that affect the ability of African American preadolescent girls and their mothers to talk openly about sex

Approximately 50% of new HIV infections in the US occur in teenagers, with African American females making up a disproportionate number. The purpose of this study was to identify factors that could encourage delaying sexual debut. Twenty-eight African American mothers and their early adolescent daughters were recruited from four inner-city community centers. Seven separate focus groups were conducted for mothers and daughters using principles of Participatory Action Research. Four codes emerged from the data: social norms regarding sex, males, self-esteem, and family structure. These codes support the importance of an intervention to facilitate sexual communication between a mother and her daughter.

Ecological influences of sexuality on early adolescent African American females

African Americans make up the greater proportion of AIDS cases in adolescent girls but little is understood about the development of sexual risk behaviors during the early adolescent years. This article will explore ecological factors influencing adolescent sexual risk behaviors. In the focus groups, which were conducted using 28 African American mothers and their early adolescent daughters, 2 major themes emerged: exposure and support systems. Mothers described the impact community had on their daughters and how monitoring and support systems worked together to control exposure. The girls detailed the different ways they were impacted by the community. Attitudes the girls adopted from their exposures resulted in risk-taking behaviors or a determination to positively impact the community. Community was shown to be the context of the acquisition of sexual knowledge and attitudes. These findings support the development of interventions to address the impact of community on the participation of sexual risk behaviors.

Heterosocial behaviors in early adolescent African American girls: the role of mother-daughter relationships

Recent epidemiological trends in HIV/AIDS have helped draw attention to minority adolescents as especially high risk for HIV acquisition. Research shows the importance of maternal-child closeness and sexual communication in decreasing adolescent risk behaviors. The information, motivation, behavioral skills model (IMB) formed the framework for this pilot study whose purpose was to examine the informational and motivational antecedents of heterosocial risks in African American middle-school-aged girls and the maternal influence on these risks. Thirty-nine mother-daughter dyads participated, of whom 54% were impoverished. The girls' intent to stay safe, perceived social norms, and closeness to mother were negatively correlated with reported participation in potentially risky situations. Early interventions may enhance mother-daughter bonding, increasing sexual communication, and decreasing girls' participation in risky behaviors. This pilot study provides direction regarding testing of the IMB model in studies focused on early adolescent behaviors and mother-daughter interactions.

Classification of grossly detectable abnormalities and conditions seen at postmortem in Canadian poultry abattoirs according to a hazard identification decision tree

This study was designed to review all grossly detectable abnormalities and conditions (GDACs) encountered in poultry in Canadian abattoirs to determine which have potential to cause adverse health effects for the consumer. Review of the literature and consultation with scientists in the field of microbiology, epidemiology, poultry pathology, chemistry, and meat inspection served to generate an inventory of GDACs, and a decision tree containing algorithms was developed to identify GDACs potentially representing a health hazard to consumers. Through the use of the decision tree, GDACs were classified into different categories with regard to the risk they represent to humans. A number of GDACs were identified as being of potential concern from a food safety perspective, namely Erysipelas, fowl cholera, Campylobacteriosis, clostridial diseases, hepatitis/enteritis associated with Helicobacter, Listeriosis, Salmonella infections (nontyphoid infections, Salmonella arizonae, pullorum disease, and fowl typhoid), Staphylococcosis, and Toxoplasmosis. Further characterization--i.e., hazard characterization, exposure assessment, and risk characterization--is required to quantify or better characterize the probability that products derived from affected carcasses may affect the consumer as well as the resulting consequences. Risk assessment is a dynamic process. Results presented in this paper are based on available information and expert opinion. As new information is obtained, the inventory of GDACs and their classification may be modified.

The normal kidney growth rate during year 1 of life is variable and age dependent

PURPOSE

The concept of normal contralateral kidney growth rate was introduced as a parameter to consider in conjunction with others in the evaluation of unilateral hydronephrosis in asymptomatic neonates and infants. Historically measurements of renal size obtained at different times from different patients have been relied on to construct normal renal growth charts. We report normal kidney growth rates in year 1 of life derived from interval ultrasound measurements of renal size in the same newborns and infants longitudinally with time.

MATERIALS AND METHODS

We reviewed 333 normal renal ultrasound studies performed between 1991 and 1995 in 55 patients during year 1 of life. These longitudinal measurements were made bilaterally 2 to 8 times (median 3) per patient. Growth curve models that consider random patient effects were used to estimate the mean growth curve and ascertain its form. We also reviewed an additional 91 ultrasound studies in 10 patients with myelomeningocele without hydronephrosis or reflux. We analyzed the kidney growth rate in a similar manner and compared the results with those in the normal patients.

RESULTS

Analysis of the normal cases revealed a changing growth rate during year 1 of life estimated to be 3.1 mm. per month at birth, decreasing gradually during the first 7 months of life to 0.25 mm. per month and remaining constant thereafter (p = 0.0064). Mean kidney size at birth was estimated to be 42.8 mm. (95% confidence limits 27.0 to 58.5). At age 7 months mean size was 60.7 mm. (95% confidence limits 40.1 to 81.3).

CONCLUSIONS

These data demonstrate that normal kidney growth is age dependent. A rapid but slowly decreasing growth rate during the first 7 months of life is followed by a more constant and lower rate. The data also suggest that unusually rapid growth, such as that which may occur in the normal contralateral kidney in unilateral obstruction, may also be age dependent, exceeding 5.0 mm. per month during the first 7 months of life and 2.0 mm. per month thereafter.

Patient satisfaction with current impotence therapy

One hundred ninety-eight impotent men were evaluated between July 1993 and June 1994. A "patient goal-directed" approach was used in all cases. Treatment options presented to patients included: oral yohimbine, vacuum constriction devices, penile self-injection therapy, penile prostheses, and testosterone supplementation when clinically indicated. Thirty-two percent of patients declined treatment, and 67% chose nonsurgical therapy. Only two patients (1%) chose penile prostheses. In August 1994, a survey addressing satisfaction with therapy was mailed to all patients, and 99 men (50%) responded. Of the treated respondents, 80% stated that their therapy was "easy to use," and 70% reported that they were "able to have intercourse." Patients prefer nonsurgical impotence therapy, which restores satisfactory sexual function in most men.

Influence of cocaine, ethanol, or their combination on epicardial coronary arterial dimensions in humans

BACKGROUND

Cocaine and ethanol are often abused concomitantly, and this combination may be more lethal than either substance alone. Although previous studies showed that cocaine causes coronary arterial vasoconstriction, the combined effect of cocaine and ethanol on the coronary vasculature in humans is unknown. Thus, we assessed the effects of intranasal cocaine, intravenous ethanol, or a cocaine-ethanol combination on heart rate, systemic arterial pressure, and coronary arterial dimensions in humans.

METHODS

Thirty-four subjects with chest pain (27 men and seven women, aged 34 to 67 years) who were referred for catheterization received one of the following pharmacologic interventions: (1) intranasal (2 mL) and intravenous (5 mL/kg) saline (n = 8 [group A]); (2) intranasal cocaine (2 mg/kg) and intravenous saline (5 mL/kg) (n = 9 [group B]); (3) intranasal saline (2 mL) and intravenous 10% ethanol (5 mL/kg) (n = 9 [group C]); or (4) intranasal cocaine (2 mg/kg) and intravenous 10% ethanol (5 mL/kg) (n = 8 [group D]). Heart rate, systemic arterial pressure, left coronary arterial dimensions (by computer-assisted quantitative angiography), as well as blood cocaine, ethanol, and cocaine metabolite concentrations were measured before and 30, 60, and 90 minutes after initiation of the intravenous infusions.

RESULTS

No hemodynamic or angiographic changes were observed in the group A (saline) subjects. In the group B (cocaine) subjects, the heart rate-systolic arterial pressure product increased by 5% and 10% at 30 and 90 minutes, respectively, and coronary arterial diameter decreased by 14% at these times. In the group C (ethanol) subjects, no hemodynamic changes were noted, but coronary arterial diameters increased by 12%, 11%, and 12% at 30, 60, and 90 minutes, respectively. In the group D (cocaine-ethanol) patients, rate-pressure product increased by 17%, 10%, and 16%, and coronary arterial diameters increased by 7%, 12%, and 13%, at 30, 60, and 90 minutes, respectively.

CONCLUSION

The combination of intranasal cocaine and intravenous ethanol causes an increase in the determinants of myocardial oxygen demand. However, it also causes a concomitant increase in epicardial coronary arterial diameter.

Differential adherence of Acanthamoeba to contact lenses: effects of material characteristics

BACKGROUND

Acanthamoeba-associated keratitis occurs most often in contact lens wearers. The contact lens material may affect its ability to act as a mechanical vector, permitting transfer of viable amoebae from the storage case to the corneal surface. The purpose of this study was to investigate the effects of ionicity and water content on the comparative quantitative adherence of Acanthamoeba trophozoites and cysts to new, unworn hydrogel contact lenses and rigid gas-permeable contact lens materials.

METHODS

Sixteen quarter segments of each of 8 types of unworn hydrogel lenses representative of FDA groups 1 to 4 were exposed to freshly prepared cultures of either trophozoites or cysts of A. castellanii or A. polyphaga for 1.5 h, and then washed. Three types of rigid lens button were similarly exposed to A. castellanii trophozoites or cysts. Adherent trophozoites and cysts were then enumerated.

RESULTS

All hydrogel lenses showed binding of both trophozoites and cysts, with the former predominating in every case. It was primarily the ionic nature of a lens surface and secondly its water content that was associated with increased quantitative adherence of Acanthamoeba. Neither form of the amoebae bound to any of the hard lens buttons.

CONCLUSIONS

Greater relative potential exists for contamination of ionic and high-water content hydrogels by Acanthamoeba. This combination may influence mechanical transmission of the protozoon to the corneal surface. Adherence to hard lenses (as buttons) did not occur if a postincubation wash step was performed.

Increased sensitivity of the rapid hydrophobic grid membrane filter enzyme-labeled antibody procedure for Escherichia coli O157 detection in foods and bovine feces

Several strains of Escherichia coli O157:H7 artificially inoculated into vegetables and dairy products were recovered on hydrophobic grid membrane filters and enumerated by an enzyme-labeled antibody assay. The mean of the recoveries from 12 fresh vegetables was 108.8%, whereas that from 10 dairy products was 93.2%. Modified tryptic soy broth at 43 degrees C with shaking at 100 rpm provided optimum recovery of the organism from meat, with a sensitivity of less than or equal to 1 CFU/g, which is 10 times more sensitive than direct plating. The method performed equally well with vegetable and dairy products. Tryptic soy broth, however, under the same conditions gave the best results for fecal samples. Of 22 asymptomatic dairy cattle, reported as having positive Brucella titers when assayed with polyclonal antibodies, eight were found to contain E. coli O157 in their feces as demonstrated by the enzyme-labeled antibody assay by using monoclonal antibodies. This finding may explain some of the false-positive Brucella tests.

Experimental oral toxicity of domoic acid in cynomolgus monkeys (Macaca fascicularis) and rats. Preliminary investigations

A recent outbreak of marine food poisoning in humans was attributed to the consumption of blue mussels (Mytilus edulis L.) contaminated with domoic acid (DA) that was produced by the diatom Nitzschia pungens. The clinical and morphological effects of single oral doses of extracts of mussels contaminated with DA or of DA isolated from toxic mussels were investigated in small groups (one to six) of cynomolgus monkeys (Macaca fascicularis; 0.5-10 mg DA/kg body weight) and of Sprague-Dawley rats (60 to 80 mg DA/kg body weight). Control animals were either given saline or were not treated. To test whether monosodium glutamate, present in the food consumed by some affected humans, and dimethylsulphoxide, suspected of being present in the plankton, enhanced the response, monosodium glutamate (at 0.25% of mussel extract bolus) or dimethylsulphoxide (at 1 g per bolus) were co-administered to two (one each) of the DA-treated monkeys. DA-treated monkeys developed transient excitation characterized by vomiting. DA-treated rats showed withdrawal followed by hyperexcitation and death (in one case). Mild to moderate central nervous system lesions consistent with neuroexcitation were present in both monkeys and rats. The addition of monosodium glutamate and dimethylsulphoxide had no significant effect on the appearance and severity of central nervous system clinical signs and lesions. The wide variations in the response of test animals to orally administered DA were attributed to the protective effect of vomiting, and to suspected incomplete or slow gastro-intestinal absorption of the toxic agent. The results reinforce the view that DA is an emetic and that under appropriate conditions may also inflict excitotoxic central nervous system damage.

Steady state verapamil tissue distribution in the dog: differing tissue accumulation

Plasma, heart, and extracardiac tissue verapamil concentrations were measured after sustained intravenous infusions in 11 dogs to determine the differential tissue accumulation of verapamil. A steady state verapamil concentration of 327 +/- 50 ng/ml decreased the mean arterial blood pressure from 104 +/- 9 to 90 +/- 6 mm Hg (p = 0.08) and the P-R interval increased from 118 +/- 4 to 176 +/- 13 ms (p less than 0.001) with second-degree atrioventricular block developing in 6 animals. Verapamil accumulated in organs in the following order: Lung much greater than kidney greater than spleen greater than ventricular myocardium = liver greater than atrial myocardium greater than cerebral cortex greater than fat = skeletal muscle. Levels in the ventricular free wall were consistently greater than atrial levels, but no difference was observed between left versus right-sided cardiac chambers. In summary, affinity of different organs for verapamil is highly variable and organ-specific; furthermore, differential intracardiac chamber accumulation occurs.

The value of confession and forgiveness according to Jung

This article represents a broad survey of the views of C. G. Jung regarding confession and for giveness. Man, a naturally religious being, has a need to confess his wrong and to gain forgiveness of one sanctioned to absolve. The curative effect of confession has been known for centuries. Without confession, man remains in moral isolation. Priests, ministers, and rabbis, as well as psychotherapists, attest to the universality of this human phenomenon. Confession is located in that place where psychology and religion meet-guilt. Jung's views on confession bridge the chasm between psychology and religion.

Expression of terminal deoxynucleotidyl transferase in human thymus during ontogeny and development

Expression of the enzyme terminal deoxynucleotidyl transferase (TdT) was studied in human thymus during ontogeny and development. In five fetal thymus samples, the enzyme activity was barely detectable. At birth, the terminal transferase activity remained low. Maximum expression of the enzyme activity occurred between 10 and 40 mo of age. Analysis of six other enzyme activities, adenosine kinase, deoxyadenosine kinase, AMP deaminase, dAMP deaminase, 5' nucleotidase, and adenosine deaminase confirmed the normal status of the thymic tissue. A careful analysis of thymic architecture revealed that involution did not occur as a result of the disease process that necessitated cardiac surgery. By immunofluorescence, the TdT antigen was localized exclusively in the nucleus of cortical thymocytes. Protein immunoblotting studies indicated that human thymic terminal transferase exists as a single high m.w. species in individuals under 30 mo of age. Thereafter, a variant m.w. species is detectable. The increase in expression of this enzyme coincides with the increase observed in serum immunoglobulin levels during maturation and precedes the maximum development of the human thymus.

Expression of terminal deoxynucleotidyl transferase in human thymus during ontogeny and development

Expression of the enzyme terminal deoxynucleotidyl transferase (TdT) was studied in human thymus during ontogeny and development. In five fetal thymus samples, the enzyme activity was barely detectable. At birth, the terminal transferase activity remained low. Maximum expression of the enzyme activity occurred between 10 and 40 mo of age. Analysis of six other enzyme activities, adenosine kinase, deoxyadenosine kinase, AMP deaminase, dAMP deaminase, 5' nucleotidase, and adenosine deaminase confirmed the normal status of the thymic tissue. A careful analysis of thymic architecture revealed that involution did not occur as a result of the disease process that necessitated cardiac surgery. By immunofluorescence, the TdT antigen was localized exclusively in the nucleus of cortical thymocytes. Protein immunoblotting studies indicated that human thymic terminal transferase exists as a single high m.w. species in individuals under 30 mo of age. Thereafter, a variant m.w. species is detectable. The increase in expression of this enzyme coincides with the increase observed in serum immunoglobulin levels during maturation and precedes the maximum development of the human thymus.

A controlled study of diet in patients with gout

To determine whether patients with gout have a diet which is distinctive in quality or quantity a careful dietary questionnaire was posed over 7 days to 61 men with gout and 52 control subjects. The average daily intake of most nutrients, including total purine nitrogen, was similar except that the patients with gout drank significantly more alcohol. Beer was the most popular beverage, and 25 (41%) of those with gout consumed more than 60 g alcohol daily (equivalent to 2 . 5 litres of beer). The heavy drinkers had a significantly higher intake of purine nitrogen, half of which was derived from beer. Though the effect of ingested purine on the blood uric acid is difficult to estimate, it probably was sufficient to have a clinical effect, augmenting the hyperuricaemic effect of alcohol itself.

Variation in Counts, Enterotoxin Levels and TNase in Swiss-Type Cheese Contaminated with Staphylococcus aureus

In 1977, a number of staphylococcal intoxications occurred as a result of several lots of Swiss-type cheese being contaminated with Staphylococcus aureus . Blocks of cheese representing 59 of the recalled lots manufactured between January 5 and April 25, 1977, were examined for S. aureus counts and for staphylococcal thermonuclease (TNase), enterotoxin and pH. Counts ranged from <25 to 10⁸ S. aureus /g, with most blocks containing between 10⁴ and 10⁶/g. Enterotoxin B was present in 72.6% of 186 samples and TNase in 52.5% of 122 samples tested. The pH was generally between 5.5 and 5.7 with some samples as high as 6.2; normal pH for Swiss-type cheese is 5.7. Variations in levels of these parameters occurred within lots and even within blocks, as well as between lots. Within blocks there seemed to be differences between samples at the center and the periphery. The activity and degree of contamination of the starter cultures, temperatures of cooking and ripening and the speed of salt penetration could be factors causing these variations. TNase was not detectable in all samples containing enterotoxin, especially those with <0.5 μg/100 g. Therefore, cheese suspected of being a health hazard, such as being manufactured under unsanitary conditions or suspected of being contaminated with S. aureus , should be sampled at the center and periphery of blocks, if these are available, and analyzed for S. aureus counts, TNase and enterotoxin.

Food Poisoning Associated with Post-Process Leakage (PPL) in Canned Foods

One hundred and fifty-four incidents of food poisoning were associated with post-process leakage (PPL) between 1921 and 1979. These occurred mainly in Great Britian (72.7%) and Canada (17.5%) from products exported from South America, Europe, Africa and Australia. Defects leading to leakage were identified as defective seams and perforations during processing; temporary microleaks during cooling; and case-cutter damage, punctures, corrosion and dents after processing. Organisms associated with the incidents were Staphylococcus aureus (100, 64.9%), Salmonella typhi (6, 3.9%), other Salmonella spp . (9, 5.8%), Clostridium botulinum (3, 2.0%), Clostridium perfringens (3, 2.0%), others and undetermined 33 (21.4%). Canned meat, fish and vegetable products were involved. In particular, corned beef contaminated with Staphylococcus or Salmonella caused 53 incidents; pork and ham products contaminated with the same organisms caused 16 incidents. Where information was available, it was found that the median amount of meat contaminated with Salmonella consumed by ill persons was 105 g. For Salmonella -contaminated fish the amount associated with illness was between 40 and 320 g. Although many of the PPL incidents recorded occurred decades ago, significant outbreaks from this cause have appeared in the last few years. Appropriate action should be taken to reduce PPL at the manufacturing and retail level.

PUBLIC HEALTH PROBLEMS ASSOCIATED WITH BARBECUED FOOD. A REVIEW

Barbecued foods are popular ready-to-eat products which are increasing in sales in many countries throughout the world. They are sold from grocery stores, restaurants, take-out shops, and outdoor stalls. These foods, mainly barbecued chicken, have caused 62 known outbreaks of food poisoning, some of them involving hundreds of people and causing deaths. Although freshly barbecued foods, adequately cooked, are wholesome and contain few bacteria, subsequent unsanitary handling and storage in inadequate holding facilities increases the risk of bacterial contamination; these bacteria may grow to hazardous levels. Stored barbecued chickens have been found with bacterial counts. Temperature control of barbecued food is considered the best way of preventing food poisoning. Unfortunately, legislation in most countries does not specify actual temperature requirements for storing of potentially hazardous foods, which includes barbecued products. We recommend that barbecued food should be stored at :≤40 F or ≥140 F.