Manganese superoxide dismutase (SOD2): is there a center in the universe of mitochondrial redox signaling?

It is becoming increasingly clear that mitochondria drive cellular functions and in vivo phenotypes by directing the production rate and abundance of metabolites that are proposed to function as signaling molecules (Chandel 2015; Selak et al. 2005; Etchegaray and Mostoslavsky 2016). Many of these metabolites are intermediates that make up cellular metabolism, part of which occur in mitochondria (i.e. the TCA and urea cycles), while others are produced "on demand" mainly in response to alterations in the microenvironment in order to participate in the activation of acute adaptive responses (Mills et al. 2016; Go et al. 2010). Reactive oxygen species (ROS) are well suited for the purpose of executing rapid and transient signaling due to their short lived nature (Bae et al. 2011). Hydrogen peroxide (H₂O₂), in particular, possesses important characteristics including diffusibility and faster reactivity with specific residues such as methionine, cysteine and selenocysteine (Bonini et al. 2014). Therefore, it is reasonable to propose that H₂O₂ functions as a relatively specific redox signaling molecule. Even though it is now established that mtH₂O₂ is indispensable, at least for hypoxic adaptation and energetic and/or metabolic homeostasis (Hamanaka et al. 2016; Guzy et al. 2005), the question of how H₂O₂ is produced and regulated in the mitochondria is only partially answered. In this review, some roles of this indispensable signaling molecule in driving cellular metabolism will be discussed. In addition, we will discuss how H₂O₂ formation in mitochondria depends on and is controlled by MnSOD. Finally, we will conclude this manuscript by highlighting why a better understanding of redox hubs in the mitochondria will likely lead to new and improved therapeutics of a number of diseases, including cancer.

First Report of Beech Bark Disease in Michigan

Beech bark disease of American beech (Fagus grandifolia) is caused by the interaction of an introduced scale insect (Cryptococcus fagisuga) and the native fungus Nectria galligena, or N. coccinea var. faginata, which is thought to be introduced. Infestations of the insect precede development of the disease, and N. galligena is often found before N. coccinea var. faginata. Previously published records indicate that the beech scale extends as far west as eastern Ohio (2) and southern Ontario (Sajan, personal communication). The scale is now well established in several locations in both the Upper Peninsula (UP) and Lower Peninsula (LP) of Michigan. The scale insect has been found in beech stands throughout three counties (Oceana, Mason, and Muskegon) along the Lake Michigan shore in the LP, extending for at least 100 km from north to south, and occurring up to about 80 km inland. In the eastern UP, beech scale has been found in four counties (Alger, Chippewa, Luce, and Schoolcraft). The heaviest beech scale infestations are distributed around Ludington State Park in the west central LP and the Bass Lake Forest Campground in the eastern UP. The extent of the insect infestation suggests that it has been present in Michigan for many years, with anecdotal accounts placing the first observations of beech scale at Ludington State Park around 1990. These infection centers are distant from previously known beech scale infestations and are located in heavily used recreation areas, suggesting that the insect may have been transported by human activity. Perithecia of N. coccinea var. faginata were found in Ludington State Park in the LP at N 44° 1.951', W 86° 29.956' and perithecia of N. galligena were found at the Bass Lake site in the UP, at N 46° 27.748', W 85° 42.478'. The identity of the fungi collected from each location was confirmed by measurements of perithecium and ascospore morphology (1). Perithecia at both sites were scarce and difficult to find. Surveys planned for the summer and fall of 2001 will further delimit the occurrence and distribution of the pathogens involved in the disease in Michigan. To our knowledge, this is the first report of the beech scale and beech bark disease in Michigan, with N. galligena and N. coccinea var. faginata identified as the pathogens. References: (1) H. V. T. Cotter and R. O. Blanchard. Plant Dis. 65:332-334, 1981. (2) M. E. Mielke et al. Plant Dis. 69:905, 1985.

Effects of tranexamic acid and aprotinin, two antifibrinolytic drugs, on PAF-induced plasma extravasation in unanesthetized rats

Two antifibrinolytic drugs, tranexamic acid (TXA), and aprotinin (APR), are currently used to improve the recovery of patients following major surgery while reducing blood loss. Their mechanisms of action have yet to be fully understood. Here, we examined (1) the effects of TXA or APR on basal vascular permeability (VP) and (2) the effects of TXA or APR on platelet-activating factor (PAF)-induced increase of VP in normal unanesthetized rats. Evans blue dye (EB) bound to albumin was used as the marker of extravasation in selected tissues. In normal rats, PAF (1 microg/kg i.v.) increased VP in most selected tissues including bronchi, aorta, duodenum and pancreas without affecting blood pressure. TXA (up to 300 mg/kg i.v.) had no significant effect on basal VP in any tissues, while APR (30000 KIU/kg i.v.) decreased basal VP in 5 out of 8 tissues. Pre-treatment with TXA decreased PAF-induced increases of VP in the microcirculation of the thoracic and abdominal aorta, the duodenum and the pancreas, from 35% to 41%. TXA was mostly effective at an i.v. dose of 100 mg/kg with a 2 h of pre-treatment period. Pre-treatment with APR also reduced PAF-induced increases of VP in selected tissues by 35 to 61%. The i.v. dose of 30000 KIU/mg was optimal when injected at least 30 min before the administration of PAF + Evans blue. These results suggest that the beneficial effect of APR and TXA, following cardiopulmonary bypass (CPB) and other type of surgeries, may be attributed to the inhibition of plasma exudation mediated, at least in part, by PAF. Thus, TXA and APR may improve patients recovery by reducing the capillary leakage of albumin, associated with interstitial edema formation, and maintaining intravascular fluid volume.

Frequency of cutaneous reactions on rechallenge with nevirapine and delavirdine

OBJECTIVE

To determine the frequency of cutaneous reactions in a group of HIV-infected adults attending a public hospital HIV clinic who received nevirapine, delavirdine, or both, as well as the consequences of rechallenge with the same or alternative agent.

DESIGN

The medical records of patients who had received either or both agents between March 1997 and July 1998 were reviewed, including 69 patients who initially received nevirapine and 20 who initially received delavirdine. Gender, ethnicity, HIV status, and plasma HIV RNA concentrations were analyzed as risk factors for the development of rash.

RESULTS

The overall incidence of rash attributed to the initial use of one of these drugs was 37.1%. While rash due to delavirdine occurred more often, the rash due to nevirapine was more severe and resulted in hospitalization more frequently. There was a trend toward a higher frequency of rash in Latinos and possibly in women, but HIV status, CD4+ cell counts, and plasma HIV RNA were not risk factors for the development of rash. Drug therapy was temporarily or permanently discontinued because of rash in 19 of 69 (28%) and in five of 20 (25%) patients initially receiving nevirapine or delavirdine, respectively. Rash recurred in six of eight (75%) patients rechallenged with the same agent, and in seven of 10 (70%) who were crossed over to the alternative agent because of rash. Fever, in the absence of any apparent cause, was a significant predictor for the development of rash in patients receiving nevirapine.

CONCLUSIONS

There is probably little value in attempting to retreat patients with cutaneous reactions, even with the alternative agent, except in patients with limited treatment options.

Phytophthora cinnamomi as a Cause of Oak Mortality in the State of Colima, Mexico

This research identifies the root pathogen Phytophthora cinnamomi as the primary cause of mortality in a 300-ha disease center of mixed oak trees in a native forest in southern Mexico. In increasing order of apparent field resistance to the disease, the major oak species are Quercus glaucoides, Q. peduncularis, and Q. salicifolia. P. cinnamomi was isolated from soil in the affected area from symptomatic trees and was successfully used to perform Koch's postulates on these three oak species. Artificial and natural infections produced vertically elongated discolorations in the outer xylem and distinctive phloem canker lesions with a sharp demarcation line between healthy and affected tissues. In Q. glaucoides there is little evidence that this oak species is able to resist the girdling effects of the phloem lesions, but in Q. peduncularis, and especially in Q. salicifolia, increased production of callus tissue around the phloem canker lesions suggests an active resistance mechanism that may allow these infected trees to survive somewhat longer. This particular incident is unlike other recent reports in other parts of the world of oak mortality caused by P. cinnamomi because the initial appearance of disease in this area is known (just prior to 1987), and it has subsequently expanded to the present area of 300 ha (in 1999) as a distinctive infection locus with periodically advancing infection fronts. This incident is also another dramatic illustration of the potential environmental damage that can result when P. cinnamomi is introduced into a simple forest ecosystem where the major overstory trees are susceptible to infection and are killed.

Aprotinin, an antifibrinolytic drug, attenuates bradykinin-induced permeability in conscious rats via platelets and neutrophils

Two antifibrinolytic drugs, tranexamic acid (TXA) and aprotinin (APR), are used to improve the recovery of patients following cardiac surgery while reducing blood loss. Their mechanisms of action have yet to be fully understood. To investigate their possible mechanisms of action during cardiopulmonary bypass, we examined (i) the effects of TXA and APR on bradykinin (BK) induced vascular permeability (VP) in conscious rats, (ii) the roles of platelets and neutrophils in this reaction, and (iii) the effects of TXA or APR on BK responses in platelet- or neutrophil-depleted rats. Evans blue dye (EB) was used as the marker of extravasation. The animals were treated with antiplatelet serum for platelet depletion or with methotrexate for neutrophil depletion. In normal rats, BK increased VP in most tissues. Thrombocytopenia and neutropenia also increased basal VP. TXA had no significant effect whereas APR decreased basal VP. In the second series of experiments, APR significantly attenuated BK-induced increases in VP, whereas TXA was completely ineffective. Platelet depletion did not affect BK-induced increases of VP, except for a massive plasma exudation in the lung parenchyma. Neutrophil depletion also had no effect on BK-induced increases of VP, except for an attenuation in the duodenum. In the third and last series of experiments, TXA potentiated the effect of BK in the upper and lower bronchi of platelet-depleted rats, compared with the effects of TXA on BK in normal animals, except in the lung parenchyma, where TXA blocked the increase of VP induced by BK. APR also potentiated the effect of BK in the lower bronchi of platelet-depleted rats. Overall, the inhibitory effect of APR on the VP induced by BK in normal rats was attenuated in platelet-depleted rats. Like TXA, APR blocked the increase of VP induced by BK in the lung parenchyma of platelet-depleted rats. In neutrophil-depleted rats, TXA did not affect the permeabilizing response to BK. In those rats, the inhibitory effect of APR against BK increases of VP was attenuated. These results show that the beneficial effect of APR, but not TXA, following cardiac surgery may be attributed to the inhibition of plasma exudation mediated, in part, by BK. In addition, platelets and neutrophils do not appear to be involved in BK-mediated plasma exudation. However, both cell types are essential for the regulation of basal VP. Finally, the mechanism underlying the protective inhibitory effect of APR on BK-induced increases of VP involves, at least in part, platelets and neutrophils, since the inhibitory effect of APR is attenuated in thrombocytopenic and neutropenic rats. Both cell types are not involved in the action of TXA on VP. Therefore, maintaining platelet and neutrophil counts following cardiopulmonary bypass could enhance the protective effect of APR.

A 5-year retrospective review of adverse drug reactions and their risk factors in human immunodeficiency virus-infected patients who were receiving intravenous pentamidine therapy for Pneumocystis carinii pneumonia

The incidence and severity of adverse drug reactions (ADRs) in human immunodeficiency virus-infected persons receiving intravenous pentamidine for Pneumocystis carinii pneumonia during a 5-year period were reviewed retrospectively. Predisposing risk factors for ADRs were identified. ADRs were included if they occurred during or within 1 week following the discontinuation of pentamidine treatment. Nephrotoxicity, dysglycemia, hepatotoxicity, hyperkalemia, and hyperamylasemia accounted for 80% of ADRs (n = 174) that occurred in 76 (71.7%) of 106 patients during 84 treatment courses of pentamidine. A significant relationship between hypoglycemia and nephrotoxicity was observed (P = .002). Four factors were significantly associated with occurrence of an ADR: number of concomitant medications (odds ratio [OR] = 1.36, P = .005), nonwhite ethnicity (OR = 5.00, P = .017), cumulative dosage of pentamidine (OR = 1.03, P = .030), and concurrent use of other nephrotoxic drugs (OR = 2.34, P = .047). Two factors, daily dosage and history of intravenous drug use, approached significance. Knowledge of and avoidance of potential risk factors might allow safer use of pentamidine and reduce the prevalence of ADRs.

Lithium and angiotensin-converting enzyme inhibitors: evaluation of a potential interaction

The potential interaction between lithium and angiotensin-converting enzyme (ACE) inhibitors was investigated in a retrospective, longitudinal, case-control study of 20 hypertensive patients previously stabilized on lithium therapy. The objective of the study was to determine the impact of ACE inhibition on steady-state lithium concentrations and to evaluate the potential association of altered lithium clearance with age, renal function, and electrolyte balance. After initiation of the ACE inhibitor, steady-state lithium concentrations increased by 36.1%, lithium clearance was reduced by 25.5% (p < 0.0001), and four patients presented with symptoms suggestive of lithium toxicity. Significant bivariate correlations were observed for lithium clearance change and age (r = -0.45; p < 0.05) and for lithium clearance change and serum creatinine (r = -0.52; p < 0.02). Multiple regression analysis indicated that 25% of the change in lithium clearance was associated with a change in serum creatinine. This percentage was increased to 35% by the inclusion of age in the regression model. None of the other variables (age, height, weight, or change in serum sodium/potassium) made a significant contribution to this model. The authors concluded that a clinically important increase in lithium concentrations can occur in patients started on ACE inhibitor therapy. As elderly patients may be uniquely predisposed to this interaction, avoidance of this medication combination in older populations should be considered.

Effects of reinforcing increases in active behavior versus decreases in sedentary behavior for obese children

This experiment tested the effects of reinforcing obese children lo be more active or less sedentary in their choice of active versus sedentary behaviors. On days I and 5, there were no contingencies for sedentary or active behaviors. During days 2 through 4, children in the Activity group were reinforced for being more active, and they significantly increased their activity and decreased time spent on preferred sedentary activities. Children in the Sedentary group were reinforced for not engaging in preferred sedentary behaviors, and they significantly decreased time spent on these sedentary behaviors, with lime reallocated both to being more active and to substitution of lower preference sedentary behaviors. Children randomized to the Control group were reinforced for attendance and made choices among the alternatives as usual, allocating most or their time during all 5 days for their preferred sedentary behaviors. These laboratory results support the idea that activity can be increased by either reinforcing children for being more active or for reducing lime spent in sedentary activities.

Genetic analysis of liver tumorigenesis in SV40 T antigen transgenic mice implies a role for imprinted genes

Liver tumors from interspecific hybrid, transgenic mice containing the SV40 early region linked to a mouse major urinary protein enhancer/promoter were analyzed for loss of heterozygosity to identify chromosomal regions which potentially contain genetic loci involved in multistep tumorigenesis. A broad pattern of complete and partial loss of heterozygosity or allelic imbalance was observed with frequent loss of heterozygosity/partial loss of heterozygosity of loci on chromosomes 1, 5, 7, 8, and 12. In tumors from Mus domesticus x Mus spretus F1 mice a strong preference for loss of the domesticus allele of H19 on chromosome 7 was observed, whereas loss of heterozygosity/partial loss of heterozygosity on chromosome 8 involved preferential loss of spretus alleles. In tumors from reciprocal crosses with Mus castaneus, the maternal chromosome 7 H19 allele was preferentially lost irrespective of whether it was domesticus or castaneus, strongly suggesting the involvement of an imprinted gene(s) in tumor progression.

Chromosome 8 alterations accompany tumorigenesis in renin-SV40 T antigen transgenic mice

s.c. and abdominal tumors from interspecific hybrid, transgenic mice containing the SV40 early region linked to a renin enhancer/promoter were analyzed for loss of heterozygosity to identify chromosomal regions involved in tumorigenesis. A very high frequency of loss of heterozygosity/partial loss of heterozygosity or allelic imbalance involving the distal regions of chromosome 8 was observed in the s.c. tumors (76%) with frequent amplification (3-6 times) of the corresponding proximal regions including Junb, suggesting that chromosome 8 breakage and amplification promotes tumorigenesis in these mice.

Diagnostic and treatment guidelines on elder abuse and neglect

It is estimated that between 1.5 and 2 million older adults experience abuse or neglect each year in the United States. Elder mistreatment may be physical, psychological, or financial, and it may be perpetrated by family members or by other informal or formal caregivers. Physicians are encouraged to play an active role in assessment, intervention, and prevention.

Acute pain in the elderly

Acute-pain syndromes are common in the elderly. They often occur in association with the degenerative diseases that are likely to affect this age-group. Diagnosis of the specific type of acute pain is made difficult by several factors, including atypical presentation and underreporting. Treatment can be complicated by the polypharmacy that is prevalent among older adults and by age-related physiologic changes. Effective management requires knowledge of the effects of various pharmacologic agents in older adults and of the health and psychosocial status of the individual patient.

Evaluation of acute confusion (delirium)

Acute confusion in the elderly is a problem that has high prevalence with significant morbidity and mortality, and that may lead to institutional placement. It is imperative that delirium be recognized promptly and its underlying cause(s) identified and treated. Management requires a multifaceted approach that addresses the precipitating cause(s), maintenance and support of vital functions, management of behaviors with use of nursing staff and family, attention to the environment, and sometimes the use of appropriate psychotropic medication. Prompt treatment is likely to result in a return to normalcy.

'Healthy' prescribing for the elderly. How to minimize adverse drug effects and prevent 'dementia in a bottle'

Despite constituting only 11% to 12% of the US population, the elderly use 31% of all prescription and over-the-counter drugs and, unfortunately, are most vulnerable to the adverse effects of drug therapy. Because of age-related physiologic changes and the likelihood of intercurrent disease, elderly patients need individualized prescribing. This requires the practitioner to be familiar with a few drugs in each class that are tolerated by and effective in elderly patients and to adhere to the principles of healthy prescribing, which have application in any setting. In conclusion, the words of Paracelsus (1493-1541) are worth recalling: "All substances are poisons; there is none which is not a poison. The right dose differentiates a poison from a remedy."

Perceptions of family practice residents toward care of the elderly

Family practice residents were surveyed to determine their perceptions of working with geriatric patients. Three areas were surveyed: residents' views of the elderly, their comparisons of the elderly with younger patients and their ideas of what it would be like to work with elderly patients. The results show that generally residents have positive views of geriatric patients. Residents see the elderly as comparing favorably with younger people. Also, they view the elderly as possessing favorable personality characteristics, such as a sense of humor, preference for independence, flexibility, and being easy to work with. Although residents are positive about working with the elderly, they do feel some ambivalence toward working in stroke-rehabilitation programs, as well as with geriatric patients who have lost contact with reality. Medical educators need to be aware of the perceptions that residents have concerning the geriatric patient, since this type of patient will in the future comprise a larger percentage of the resident's practice.

Leiomyoma of the omentum in a child

Leiomyoma of the omentum is a rare tumor. This is a report of the first known case of such a tumor presenting in childhood.

Knowledge and attitudes of family practice residents toward geriatric patients

The knowledge and attitudes of family practice residents toward geriatric patients was surveyed in eight residencies. Since geriatric care will, in the future, become a more important aspect of the family physician's practice, it is important to ascertain the knowledge and attitude level of physicians in training concerning their geriatric patients. Three aspects of this study indicate serious deficits in the educational background of these residents: the number and quality of courses offered to them is inadequate; they demonstrate a paucity of knowledge concerning the aged; the residents show a low preference for working with the aged. Clearly, medical education should address these needs and deficits.