United States-Mexico Border Disparities in Alcoholic Liver Disease Mortality: A Cross-Sectional Analysis 1999-2020

BACKGROUND

US-Mexico (US-MX) border regions are impacted by socioeconomic disadvantages. Alcohol use disorder remains widely prevalent in US-MX border regions, which may increase the risk of alcoholic liver disease (ALD).

GOALS

We aimed to characterize ALD mortality trends in border regions compared to non-border regions from 1999 to 2020 in the United States (US).

METHODS

We performed a cross-sectional analysis using the CDC repository. We queried death certificates to find ALD-related deaths from 1999 to 2020, which included demographic information such as gender, race/ethnicity, and area of residence. We estimated age-adjusted mortality rates (AAMR) per 100,000 population and compared the AAMRs across border and non-border regions. We also explored yearly mortality shifts using log-linear regression models and calculated the average annual percentage change (AAPC) using the Monte Carlo permutation test.

RESULTS

In all, 11,779 ALD-related deaths were identified in border regions (AAMR 7.29) compared with 361,523 in non-border regions (AAMR 5.03). Border male (AAMR 11.21) and female (AAMR 3.77) populations were higher compared with non-border male (AAMR 7.42) and female (2.85) populations, respectively. Border non-Hispanic populations (AAMR 7.53) had higher mortality compared with non-border non-Hispanic populations (4.79), while both populations experienced increasing mortality shifts (AAPC +1.7, P<0.001 and +3.1, P<0.001, respectively). Border metropolitan (AAMR 7.35) and non-metropolitan (AAMR 6.76) regions had higher mortality rates compared with non-border metropolitan (AAMR 4.96) and non-metropolitan (AAMR 5.44) regions.

CONCLUSIONS

Mortality related to ALD was higher in border regions compared with non-border regions. Border regions face significant health disparities when comparing ALD-related mortality.

Influence of Social Vulnerability Index on Medicare Beneficiaries' Expenditures upon Discharge

Medicare beneficiaries' healthcare spending varies across geographical regions, influenced by availability of medical resources and institutional efficiency. We aimed to evaluate whether social vulnerability influences healthcare costs among Medicare beneficiaries. Multivariable regression analyses were conducted to determine whether the social vulnerability index (SVI), released by the CDC, was associated with average submitted covered charges, total payment amounts, or total covered days upon hospital discharge among Medicare beneficiaries. We used information from discharged Medicare beneficiaries from hospitals participating in the Inpatient Prospective Payment System. Covariate adjustment included demographic information consisting of age groups, race/ethnicity, and Hierarchical Condition Category risk score. The regressions were performed with weights proportioned to the number of discharges. Average submitted covered charges significantly correlated with SVI (β=0.50, p<0.001) in the unadjusted model and remained significant in the covariates-adjusted model (β=0.25, p=0.039). The SVI was not significantly associated with the total payment amounts (β=-0.07, p=0.238) or the total covered days (β=0.00, p=0.953) in the adjusted model. Regional variations in Medicare beneficiaries' healthcare spending exist and are influenced by levels of social vulnerability. Further research is warranted to fully comprehend the impact of social determinants on healthcare costs.

Efficacy and safety of fenofibrate in combination with phototherapy for the treatment of neonatal hyperbilirubinemia: a systematic review and meta-analyses

Phototherapy is the standard treatment for neonatal jaundice. We aimed to review the efficacy and safety of fenofibrate as an adjunct therapy. Twelve databases were searched and a systematic review and meta-analysis were conducted. Mean change (MC), mean difference (MD), and risk ratios (RR) with a 95% confidence interval (CI) were calculated using a random effects model. The GRADE approach was used to evaluate the evidence's certainty. Nine randomized trials were included. The MC of total serum bilirubin (mg/dL) was significant at 12, 24, 36, 48, and 72 h with respective MC (95% CI) values of -0.46 (-0.61, -0.310), -1.10 (-1.68, -0.52), -2.06 (-2.20, -1.91), -2.15 (-2.74, -1.56), and -1.13 (-1.71, -0.55). The FEN + PT group had a shorter duration of phototherapy (MD: -14.36 h; 95% CI: -23.67, -5.06) and a shorter hospital stay (MD: -1.40 days; 95% CI: -2.14, -0.66). There was no significant difference in the risk of complications (RR: 0.89; 95% CI: 0.54, 1.46) or the need for exchange transfusion (RR: 0.58; 95% CI: 0.12, 2.81). The certainty of the evidence was very low for all outcomes. In conclusion, fenofibrate might be a safe adjunct to neonatal phototherapy. Larger randomized controlled trials are needed for the confirmation of these results.

Dynamic electrocardiogram changes are a novel risk marker for sudden cardiac death

BACKGROUND AND AIMS

Electrocardiogram (ECG) abnormalities have been evaluated as static risk markers for sudden cardiac death (SCD), but the potential importance of dynamic ECG remodelling has not been investigated. In this study, the nature and prevalence of dynamic ECG remodelling were studied among individuals who eventually suffered SCD.

METHODS

The study population was drawn from two prospective community-based SCD studies in Oregon (2002, discovery cohort) and California, USA (2015, validation cohort). For this present sub-study, 231 discovery cases (2015-17) and 203 validation cases (2015-21) with ≥2 archived pre-SCD ECGs were ascertained and were matched to 234 discovery and 203 validation controls based on age, sex, and duration between the ECGs. Dynamic ECG remodelling was measured as progression of a previously validated cumulative six-variable ECG electrical risk score.

RESULTS

Oregon SCD cases displayed greater electrical risk score increase over time vs. controls [+1.06 (95% confidence interval +0.89 to +1.24) vs. -0.05 (-0.21 to +0.11); P < .001]. These findings were successfully replicated in California [+0.87 (+0.7 to +1.04) vs. -0.11 (-0.27 to 0.05); P < .001]. In multivariable models, abnormal dynamic ECG remodelling improved SCD prediction over baseline ECG, demographics, and clinical SCD risk factors in both Oregon [area under the receiver operating characteristic curve 0.770 (95% confidence interval 0.727-0.812) increased to area under the receiver operating characteristic curve 0.869 (95% confidence interval 0.837-0.902)] and California cohorts.

CONCLUSIONS

Dynamic ECG remodelling improved SCD risk prediction beyond clinical factors combined with the static ECG, with successful validation in a geographically distinct population. These findings introduce a novel concept of SCD dynamic risk and warrant further detailed investigation.

Ischemic heart disease mortality in individuals with inflammatory bowel disease: A nationwide analysis of disparities in the United States

INTRODUCTION

Inflammatory bowel disease (IBD) is linked to immune-mediated pathogenesis and a pro-inflammatory state, leading to accelerated atherosclerosis. This earlier onset of clinical cardiovascular disease poses significant morbidity and mortality. We sought to identify IHD mortality trends in individuals with IBD in the United States (US).

METHODS

Mortality due to ischemic heart diseases (IHD) as the underlying cause of death with the IBD as a contributor of death were queried from death certificates using the CDC database from 1999 to 2020. Yearly crude mortality rates (CMR) were estimated by dividing the death count by the respective population size, reported per 100,000 persons. Mortality rates were adjusted for age using the Direct method and compared by demographic subpopulations. Log-linear regression models were utilized to assess temporal variation (annual percentage change [APC]) in mortality.

RESULTS

Age-adjusted mortality rates (AAMR) decreased from 0.11 in 1999 to 0.07 in 2020, primarily between 1999 and 2018 (APC -4.41, p < 0.001). AAMR was higher among male (AAMR 0.08) and White (AAMR 0.08) populations compared to female populations (AAMR 0.06) and Black (AAMR 0.04) populations, respectively. No significant differences were seen when comparing mortality between urban (AAMR 0.07) and rural (AAMR 0.08) regions. Southern US regions (AAMR 0.06) had the lowest mortality rates when compared to the other US census regions: Northeastern (AAMR 0.08), Midwestern (AAMR 0.08), and Western (AAMR 0.08).

CONCLUSION

Disparities in IHD mortality exist among individuals with IBD in the US based on demographic factors, with an overall decline in mortality during the 22-year period. Further investigation is warranted to confirm these findings and evaluate for contributors to the observed disparities.

Artificial Intelligence Model Predicts Sudden Cardiac Arrest Manifesting With Pulseless Electric Activity Versus Ventricular Fibrillation

BACKGROUND

There is no specific treatment for sudden cardiac arrest (SCA) manifesting as pulseless electric activity (PEA) and survival rates are low; unlike ventricular fibrillation (VF), which is treatable by defibrillation. Development of novel treatments requires fundamental clinical studies, but access to the true initial rhythm has been a limiting factor.

METHODS

Using demographics and detailed clinical variables, we trained and tested an AI model (extreme gradient boosting) to differentiate PEA-SCA versus VF-SCA in a novel setting that provided the true initial rhythm. A subgroup of SCAs are witnessed by emergency medical services personnel, and because the response time is zero, the true SCA initial rhythm is recorded. The internal cohort consisted of 421 emergency medical services-witnessed out-of-hospital SCAs with PEA or VF as the initial rhythm in the Portland, Oregon metropolitan area. External validation was performed in 220 emergency medical services-witnessed SCAs from Ventura, CA.

RESULTS

In the internal cohort, the artificial intelligence model achieved an area under the receiver operating characteristic curve of 0.68 (95% CI, 0.61-0.76). Model performance was similar in the external cohort, achieving an area under the receiver operating characteristic curve of 0.72 (95% CI, 0.59-0.84). Anemia, older age, increased weight, and dyspnea as a warning symptom were the most important features of PEA-SCA; younger age, chest pain as a warning symptom and established coronary artery disease were important features associated with VF.

CONCLUSIONS

The artificial intelligence model identified novel features of PEA-SCA, differentiated from VF-SCA and was successfully replicated in an external cohort. These findings enhance the mechanistic understanding of PEA-SCA with potential implications for developing novel management strategies.

Impact of social vulnerability on comorbid COVID-19 and acute myocardial infarction mortality in the United States

The trajectory of several cardiovascular diseases (CVD), including acute myocardial infarction (AMI), has been adversely impacted by COVID-19, resulting in a worse prognosis. The Social Vulnerability Index (SVI) has been found to affect certain CVD outcomes. In this cross-sectional analysis, we investigated the association between the SVI and comorbid COVID-19 and AMI mortality using the CDC databases. The SVI percentile rankings were divided into four quartiles, and age-adjusted mortality rates were compared between the lowest and highest SVI quartiles. Univariable Poisson regression was utilized to calculate risk ratios. A total of 5779 excess deaths and 1.17 excess deaths per 100,000 person-years (risk ratio 1.62) related to comorbid COVID-19 and AMI were attributable to higher social vulnerability. This pattern was consistent across the majority of US subpopulations. Our findings offer crucial epidemiological insights into the influence of the SVI and underscore the necessity for targeted therapeutic interventions.

Alcoholic cardiomyopathy mortality and social vulnerability index: A nationwide cross-sectional analysis

Background

Social vulnerability index (SVI) plays a pivotal role in the outcomes of cardiovascular diseases and prevalence of alcohol use. We evaluated the impact of the SVI on alcoholic cardiomyopathy (ACM) mortality.

Methods

Mortality data from 1999 to 2020 and the SVI were obtained from CDC databases. Demographics such as age, sex, race/ethnicity, and geographic residence were obtained from death certificates. The SVI was divided into quartiles, with the fourth quartile (Q4) representing the highest vulnerability. Age-adjusted mortality rates across SVI quartiles were compared, and excess deaths due to higher SVI were calculated. Risk ratios were calculated using univariable Poisson regression.

Results

A total of 2779 deaths were seen in Q4 compared to 1672 deaths in Q1. Higher SVI accounted for 1107 excess-deaths in the US and 0.05 excess deaths per 100,000 person-years (RR: 1.38). Similar trends were seen for both male (RR: 1.43) and female (RR: 1.67) populations. Higher SVI accounted for 0.06 excess deaths per 100,000 person-years in Hispanic populations (RR: 2.50) and 0.06 excess deaths per 100,000 person-years in non-Hispanic populations (RR: 1.46).

Conclusion

Counties with elevated SVI experienced higher ACM mortality rates. Recognizing the impact of SVI on ACM mortality can guide targeted interventions and public health strategies, emphasizing health equity and minimizing disparities.

Intracerebral hemorrhage mortality in individuals with atrial fibrillation: a nationwide analysis of mortality trends in the United States

BACKGROUND

Atrial fibrillation (AF) is a risk factor for intracerebral hemorrhage (ICH), both with and without use of anticoagulation. Limited data exists on mortality trends and disparities related to this phenomenon. We aimed to assess ICH mortality trends and disparities based on demographic factors in individuals with atrial fibrillation in the United States (US).

METHODS

Our cross-sectional analysis utilized mortality data from the CDC database through death certificate queries from the years 1999 to 2020 in the US. We queried for all deaths with ICH as the underlying cause of death and atrial fibrillation as the multiple causes of death. Mortality data was obtained for overall population and demographic subpopulations based on sex, race and ethnicity, and geographic region. Trend analysis and average annual-mortality percentage change (AAPC) were completed using log-linear regression models.

RESULTS

ICH age-adjusted mortality rate (AAMR) in patients with AF increased from 0.27 (95% CI 0.25-0.29) in 1999 to 0.30 (95% CI 0.29-0.32) in 2020. A higher mortality rate was observed in males (AAMR 0.33) than in females (AAMR 0.26). The highest mortality was found in Asian/Pacific Islander (AAMR: 0.32) populations, followed by White (AAMR: 0.30), Black (AAMR: 0.15), and American Indian/Alaska Native (AAMR: 0.11) populations. Southern (AAPC: 1.3%) and non-metropolitan US regions (AAPC: + 1.9%) had the highest increase in annual mortality change.

CONCLUSION

Our findings highlight the disparities in ICH mortality in patients with AF. Further investigation is warranted to confirm these findings and evaluate for contributors to the observed disparities.

Laparoscopic appendectomy: an efficacious alternative for complicated appendicitis in children

INTRODUCTION

Laparoscopic appendectomy is now well accepted for the treatment of uncomplicated appendicitis in children. Nevertheless, the effectiveness and safety of laparoscopy in cases with complicated appendicitis is still controversially discussed. This study evaluates outcomes of laparoscopic appendectomies in children presenting with complicated appendicitis.

MATERIAL AND METHODS

Over a 5-year period (2002-2007), all children presenting to the authors with complicated appendicitis were approached laparoscopically using a standardized protocol and their intra-operative findings and postoperative outcomes were recorded.

RESULTS

Seventy-two consecutive laparoscopic appendectomies for complicated appendicitis were performed with no conversions. The average patient age was 8.5 years. The mean operating time was 45 min. There were no peri-operative complications. The overall rate of postoperative infectious complications was 8.3% (One child developed a large pelvic abscess required ultrasound-guided percutaneous drainage. Two children had multiple intra-abdominal abscesses that resolved with antibiotic treatment. Umbilical port-site infections were encountered in 3 patients). The average length of hospital stay was 5.7 days.

CONCLUSIONS

Laparoscopic appendectomy can be performed safely in children who present with complicated appendicitis. The procedure is efficacious and the complication rate is low.

Basal cell carcinoma on the neck

BACKGROUND

In our Mohs surgery practice, a large number of basal cell carcinomas (BCCs) occurring on the neck were noted to be of the superficial type.

OBJECTIVE

Our purpose was to examine a series of consecutive cases of BCC on the neck.

METHODS

We reviewed all cases of BCC on the neck that were treated in our Mohs surgery unit from 1988 to 1993. Permanent histologic sections of the BCCs, obtained by excisional debulking of the tumors, were examined and the BCCs were typed histologically. Each histologic type was correlated with the patient's age, race, sex, its location on the neck, and its status as either a primary or recurrent lesion.

RESULTS

In total, 97 BCCs on the neck from 93 patients were examined. All patients were Caucasians with an average age of 62.7 years. A peak incidence in the fifth decade occurred in males while this peak occurred in the eighth decade for females. Males outnumbered females 3.4:1. The type and incidence of each BCC was studied with the following results: superficial (38.1%), mixed-superficial (30.0%), nodular (15.5%), infiltrative (7.2%), morpheaform (5.1%), adenoid (2.1%), keratotic (1.0%), and metatypical (1.0%). Fifty-one percent of the tumors were primary and 49% were recurrent. The most common location on the neck was the skin overlying the superior aspect of the sternocleidomastoid muscles.

CONCLUSION

BCCs occurring on the neck were most commonly of the superficial type.

Natural killer cell and lymphokine-activated killer cell activity against melanocytes in vitiligo

BACKGROUND

Vitiligo is a common disease of unknown cause. Previous studies have shown abnormalities in natural killer (NK) cell cytotoxicity in patients when NK-sensitive erythroleukemic cell lines were used as target cells.

OBJECTIVE

The purpose of this study was to use melanocytes directly as target cells to determine NK and lymphokine-activated killer (LAK) cell cytotoxicity in patients with vitiligo and to determine whether NK or LAK cells can be implicated in any destructive mechanism for melanocyte cytotoxicity in vitro in this disease.

METHODS

Twenty-one patients with vitiligo were compared with a control group by studying NK cell activity (NKCA) and LAK cell activity (LAKCA) on several target cells. These included K562 cells, neonatal melanocytes, and malignant melanoma cells for NKCA and neonatal melanocytes and malignant melanoma cells for LAKCA. Cytotoxicity was measured with the standard chromium 51-release assay.

RESULTS

No significant differences were found between vitiligo patients and control subjects in NKCA against K562 cells or in NKCA and LAKCA against melanocytes.

CONCLUSION

NK cells and LAK cells are probably not responsible for melanocyte destruction in vitiligo.

Artificial nerve graft using glycolide trimethylene carbonate as a nerve conduit filled with collagen compared to sutured autograft in a rat model

A study was conducted to compare the regeneration of rat peroneal nerves across 0.5 cm gaps repaired with artificial nerve grafts (ANG) versus sutured autografts (SAG). The ANG model is composed of a synthetic biodegradable passive conduit made of glycolide trimethylene carbonate (GTMC) filled with a collagen matrix (predominantly Type I collagen, derived from calf skin, and with the telopeptide ends left intact). Axonal regeneration was studied in 11 long-term animals (two at 6 months and nine at 9 months). The nerves were studied by qualitative and quantitative histological, electrophysiological, and functional assays. Axonal regeneration with the ANG was equal to SAGs as measured by axonal diameters, physiological, and functional methods, although the SAG demonstrated statistically higher axonal counts.

Application of a stability statistic to international maize yield trials

Genotype x environment (GE) interaction encountered in experiments complicates genotype selection and varietal recommendation. The integration of yield and stability of genotypes into a single parameter may make selection and recommendation easier. Kang developed a rank-sum method that allows selection for both yield and the stability variance statistics (σ i (2) or s i (2) ) of Shukla. The objective of this research was to compare the rank-sum selection method to selection based on yield alone in five international maize (Zea mays L.) yield trials. Ranks were assigned for yield (the highest mean yield received a rank of 1) and for σ i (2) and s i (2) (the lowest value received a rank of 1). The yield and σ i (2) ranks and/or the yield and s i (2) ranks for each genotype were summed. Each trial contained two reference entries (REs). Yield rank or rank-sum of each genotype was compared to yield rank or rank-sum of the best RE (BRE). GE interaction was significant for all trials. Heterogeneity in the GE interaction due to the linear effect of a covariate (differences in fertility and/or cultural practices) was significant in Trials 1, 2, and 5. Overall, in all trials, 29 genotypes were selected on the basis of yield alone. On the basis of σ i (2) and yield rank-sum, 32 genotypes were identified, with 11 being lower yielding than the 29 yield-based selections. On the basis of s i (2) and yield rank-sum, 31 genotypes were selected, with 11 being lower yielding than the yield-bases selections. Obviously, yield is sacrificed when the rank-sum method is used in the selection process. However, selection based on yield alone may not be adequate when GE interaction is significant because of testing in diverse environments.

Comparison of nerve repair techniques: suture vs. avitene-polyglycolic acid tube

A study was designed to determine whether a completely sutureless technique of nerve repair using avitene and polyglycolic acid (PGA) tube could provide a better repair than the standard suture repair technique. Randomized peroneal nerves of 18 male Sprague-Dawley rats were used. The study was divided into two parts. The first part was designed to test the adhesive and tensile strength of avitene at the second postoperative day in seven animals. The tensile strength of the suture repair at 498 mN +/- 130 was found to be statistically equivalent (p = 0.77) to the repair using avitene and PGA tube at 474 mN +/- 192. The second part of the study evaluated axonal regeneration in 11 animals. Evaluation by electrophysiology revealed a significant difference (p = 0.05) between the mean percentage of Integrated Mean Compound Action Potential for the suture repaired nerve (53.1 +/- 17.6 percent) and that of the avitene and PGA tube repaired nerve (72.0 +/- 17.9). The mean axonal count and mean fiber diameter for the suture repair technique (1,879 +/- 225 and 4.3 +/- 0.4 microns, respectively) were not significantly different (p = 0.61 and 0.67, respectively) from those of the avitene-PGA tube repair technique (1,938 +/- 398 and 4.2 +/- 0.4 microns, respectively).

Artificial nerve graft using collagen as an extracellular matrix for nerve repair compared with sutured autograft in a rat model

A study was conducted to compare the regeneration of rat peroneal nerves across 0.5-cm gaps repaired with artificial nerve grafts versus sutured autografts. The artificial nerve graft model is composed of a synthetic biodegradable passive conduit made of polyglycolic acid filled with a collagen extracellular matrix (predominantly Type I collagen, derived from calf skin, and with the telopeptide ends left intact). Axonal regeneration was studied in 22 long-term animals (11 or 12 months). The nerves were studied by qualitative and quantitative histological and electrophysiological methods, and by functional analysis in 9 of the animals. The axonal regeneration of the artificial nerve graft is equal to sutured autografts as measured by axonal counts, and by physiological and functional methods, although the sutured autografts demonstrated statistically superior axonal diameters.

Audiological manifestations of Ramsay Hunt syndrome

Ramsay Hunt syndrome is known to cause audiological signs and symptoms, including sudden, unexpected hearing loss. We carried out a retrospective review of the audiological manifestations of 186 patients with Ramsay Hunt syndrome, measuring their hearing loss patterns, hyperacusis, tinnitus, herpetic rash, facial paralysis, pain and vertigo. Statistical correlations of these parameters were equated with prognosis. Prognosis for eventual hearing recovery is, in general, excellent. Prognostic indicators of poor hearing recovery include advanced age, retrocochlear hearing loss, male gender, vertigo, and speech frequency hearing loss.

Micropigmentation for the treatment of vitiligo

A technique of permanent dermal micropigmentation using a nonallergenic iron oxide pigment to cover recalcitrant areas of vitiligo is described. The areas included in this study were the distal digits, the lips, hands, wrists, axillae, elbows, hairline, perioral area, and lower legs. The immediate postmicropigmentation results invariably showed dramatic aesthetic improvements. There was a moderate degree of fading in the majority of cases, most of which occurred within the first six weeks. The pigment that remained usually persisted with minimal to no further fading. Short- and long-term complications, which were few, mild, and resolved fully, are discussed. No allergic reactions to the pigment or koebnerization of the vitiligo have been noted.

Fascicular tubulization: a comparison of experimental nerve repair techniques in the cat

Peripheral nerve repair remains one of the most difficult problems in hand surgery; the results of conventional epineurial and fascicular suture repair are a major limitation to the rehabilitation of the patient. The aim of this study was to evaluate a tubulization technique of nerve repair by wrapping a membrane of hypoantigenic collagen around the nerve at the fascicular level. Cat ulnar and median nerves were used as a multifascicular nerve model. Thirty-eight animals were studied. Ten animals were included in long-term studies comparing fascicular tubulization to either epineurial suture or fascicular suture nerve repair. Histologically, the tube repairs demonstrated improved organization at the repair site compared with either suture technique. Tube repair is not significantly different statistically by quantitative histological and physiological evaluation methods from epineurial suture or fascicular suture repairs. Further studies in more clinically applicable animal models are required before this technique can be considered as an alternative to present clinical nerve suture techniques.

Rubber band as external assist device to provide simple grip for quadriplegic patients

The rubber band as an external assist device provides an effective grip for the hand of high spinal cord injury quadriplegic patients. This technique can also be useful for preoperative patients who are undergoing physical and occupational therapy or to assess patients' needs for surgery. The rubber band as an adaptive device is preferred because of its availability, low visibility, and ease of application. We attempt to provide a more standardized method of the rubber band technique and to popularize it.

Relationships between structures and mutagenic potencies of 16 heterocyclic nitrogen mustards (ICR compounds) in Salmonella typhimurium

16 heterocyclic nitrogen mustards (ICR compounds), which were synthesized for use as possible antitumor agents by Creech and coworkers, were tested for mutagenicity in Salmonella typhimurium strains TA1535, TA1536, TA1537, TA1538, TA98 and TA100. The compounds were incorporated into the top agar at 5 doses: 0.5, 1, 2.5, 5 and 10 micrograms/plate. All of the compounds were negative in TA1535 except ICR 449, which was positive in all 6 strains. The other 15 compounds were positive in the remaining strains with the following exceptions: ICR 371 and 355 were negative in TA100; ICR 445 was negative in TA98 and TA100; and ICR 360 was negative in TA1537, TA1538, TA98 and TA100. Good qualitative agreement was observed between the mutagenic and antitumor activities of the 16 compounds, and between the mutagenic and carcinogenic activities of the 5 compounds that have been tested for carcinogenicity by Peck and coworkers. However, no significant correlation was found between mutagenic potency in Salmonella and antitumor potency in mice for the 16 compounds. Also, for the 5 compounds that have been tested for carcinogenicity, no significant correlation was found between their mutagenic potency in Salmonella and their carcinogenic potency in mice. In Salmonella, the secondary (2 degrees) amines generally were more mutagenic than their tertiary (3 degrees) amine homologs, although the opposite result has been reported in certain eukaryotes. Relationships between structures and potencies for the different nuclei of the 16 ICR compounds are discussed, as are similarities and differences in strain sensitivities. We conclude that the Salmonella his reversion test is not a good predictor of the antitumor and carcinogenic potencies of these ICR compounds.

Loss of Sensitivity to Helminthosporium maydis Race T Toxin during Aging of Mitochondria Isolated from Texas Cytoplasm Corn

Helminthosporium maydis Race T toxin caused the expected changes in freshly isolated mitochondria from T cytoplasm corn, namely complete uncoupling of oxidative phosphorylation, pronounced stimulation of succinate and NADH respiration, complete inhibition of malate respiration, and increased mitochondrial swelling. In contrast, identical toxin treatments of the mitochondria after 12 hours aging on ice resulted in partial uncoupling, much lower stimulation of succinate and NADH respiration, no inhibition of malate respiration, and no mitochondrial swelling. Almost all of the toxin sensitivity was lost by 6 hours aging. At this stage, the mitochondria were 208x and 66x less sensitive to toxin-induced changes in coupling of malate respiration and state 4 malate respiration rates, respectively. Loss of toxin sensitivity did not occur when the mitochondria were aged under nitrogen or in the presence of 5 millimolar dithiothreitol. This suggested that the aging effect was due to oxidation, possibly of sulfhydryl groups in one or more mitochondrial membrane proteins.

Mutagenicity of skin tanning lotions

Two lotions that tan skin in the absence of sunlight and their active ingredient, dihydroxyacetone (DHA), are mutagenic in Salmonella typhimurium strain TA100 without metabolic activation. However, addition of S-9 mix that contains Aroclor 1254-induced rat hepatic microsomes enhances significantly the mutagenic activity of all three agents. Both lotions and DHA also cause primary DNA damage as determined by the rec-assay in Bacillus subtilis. The potential human health hazard of these lotions is discussed.