Baseline Differences in Driving Frequency as a Predictor of Cognitive Decline and Alzheimer's Disease

OBJECTIVE

To extend prior research by examining daily driving frequency as a predictor of cognitive decline and later diagnosis of Alzheimer's disease.

METHODS

1,426 older adults completed batteries of questionnaires and neuropsychological tests at baseline and yearly follow-ups (M = 6.8, SD = 4.9). Linear mixed effects models were estimated to examine whether daily driving frequency at baseline was predictive of cognitive decline while accounting for IADLs, mobility, depression, and demographics. Cox regression was used to examine driving frequency as a predictor of Alzheimer's disease diagnosis.

RESULTS

Less daily driving frequency was associated with greater decline in all cognitive domains over time except for working memory. Although driving frequency was associated with these changes in cognition, it did not uniquely predict the development of Alzheimer's disease when accounting for other factors (eg, other IADLs).

CONCLUSIONS

Our findings extend prior research linking driving cessation to greater levels of cognitive decline. Future work might benefit from examining the utility of driving habits (especially changes in driving) as measures of everyday functioning in older adult evaluations.

Longitudinal assessment of mental health after a flood: roles of social support, hope, recovery stressors, and prior lifetime trauma

OBJECTIVES

Severe weather events have mental health consequences for survivors that may change over time. We assessed post-flood mental health longitudinally in three groups of mostly middle-aged and older adults who varied in current and prior severe weather experiences.

METHOD

Predictors of central interest were age, perceived social support, state hope (including agency and pathways), recovery stressors, and prior lifetime trauma. Criterion variables included symptoms of depression, post-traumatic stress disorder (PTSD), and worry.

RESULTS

Analyses of variance yielded significant Disaster Exposure Group x Wave interactions for depression and PTSD symptoms. Those with flooded homes and properties had elevated symptoms at Wave 1 which were reduced at Wave 2. Older age was associated with fewer symptoms of depression, PTSD, and worry. Recovery stressors and lifetime trauma predicted more PTSD symptoms. Greater agency predicted less PTSD and depression symptoms, whereas pathways predicted less worry.

CONCLUSION

These data show that mental health symptoms may decrease over time for those directly impacted by severe flooding. State hope appears to contribute to better mental health after exposure to a devastating flood. Implications for understanding the dynamic relationships among risk variables and positive factors that promote post-disaster mental health in the years after a flood are considered.

Value-consistent rehabilitation is associated with long-term psychological flexibility and quality of life after traumatic brain injury

Meaningful steps have been taken toward using holistic approaches in outpatient rehabilitation for traumatic brain injury (TBI) (i.e., treating the whole individual); however, research and practice continue to disproportionately focus on adapting to physical and cognitive changes. Research suggests treatment focusing on individual values may be important for psychological adjustment after TBI. The current study sought to explore individual values across multiple life domains in those with TBI as well as what values outpatient rehabilitation was helpful for, and to examine discrepancies between these factors (i.e., value-consistent rehabilitation) in relation to important long-term treatment outcomes. 215 adults with a history of TBI who had participated in outpatient rehabilitation completed online surveys assessing how consistent outpatient rehabilitation was with individual values, psychological flexibility, and quality of life. The life domains with the greatest discrepancies between individual importance and rehabilitation helpfulness were spirituality, intimate relations, and family relations. Greater value-consistent rehabilitation was associated with higher levels of psychological flexibility and quality of life beyond demographics and injury characteristics. Our findings provide further support in favour of holistic, client-centred approaches that are facilitated by neurological rehabilitation programs.

Religiosity and Social Support Predict Resilience in Older Adults After a Flood

In this study, we examined religiosity and social support as predictors of resilience after a devastating flood. Three flood exposure groups of primarily middle-aged and older adults were compared: (1) non-flooded adults as controls, (2) once-flooded adults with structural damage to homes and property in the 2016 flood, and (3) twice-flooded adults who had relocated inland because of prior catastrophic losses in the 2005 Hurricanes Katrina and Rita and then flooded again in 2016. Resilience was assessed using the Connor-Davidson Resilience Scale (CD-RISC). Correlation analyses confirmed that older age was correlated with higher religiosity, charitable work done for others, and resilience. Regression analyses indicated that religious beliefs and coping, social support, and charitable work done for others were associated with higher levels of resilience, whereas flood damage was unrelated to resilience. Implications for current views on post-disaster adversity and resilience in later life are discussed.

Resilience as a moderator of depression and anxiety: a bidimensional approach to predictors of subjective cognition in older adults

OBJECTIVES

Subjective cognitive complaints (SCCs) have shown to be useful predictors of objective cognitive decline in older adults. Though psychopathology symptoms (e.g. depression, anxiety) have been linked to SCCs, little is known about the influence of positive psychology factors (e.g. resilience) on these complaints. The current study aimed to determine whether resilience predicts SCCs, and whether greater resilience moderates (or lessens) the effect of negative mental health symptoms on SCCs.

METHODS

Four hundred twenty-eight adults aged 60 years or older (M = 67.6, SD = 5.9) were recruited to participate in an online Qualtrics survey study. Surveys included assessed psychological resilience [University of Washington Resilience Scale 8-item short form (UWRS-8)], depression [Geriatric Depression Scale (GDS-15)], anxiety [Geriatric Anxiety Scale (GAS-30)], and SCCs [Perceived Deficits Questionnaire-Depression (PDQ-D); Barkley Deficits in Executive Functioning Scale-Short Form (BDEFS-SF)].

RESULTS

Although greater resilience was only independently associated with less complaints on BDEFS total scores, resilience moderated (i.e. reduced) the negative effects of depression and anxiety on PDQ-D retrospective memory and planning subscales as well as BDEFS-SF total scores. Resilience also moderated (i.e. reduced) the negative effect of anxiety on PDQ-D total scores.

CONCLUSION

With resilience lessening the effect of depression and anxiety on SCCS, our findings suggest positive psychological factors may be useful for understanding the prevalence of complaints. Future research should seek to replicate these findings and investigate relationships between additional positive psychological factors and cognitive health in old age including the use of both objective and subjective assessments of cognition.

Knee pain · no popping · no previous trauma · Dx?

A 36-year-old man sought care at our family medicine clinic for knee pain that he'd had for the past year. He denied any previous injury or trauma to the knee. The pain affected the posterolateral left knee and was aggravated by squatting and deep flexion. Daily activities did not bother him, but skiing, golfing, mountain biking, and lifting weights worsened the pain. His pain had gradually become more severe and frequent. He denied any mechanical symptoms such as catching, popping, or locking.

STUDIES ON THE INTRACELLULAR DIGESTIVE PROCESS IN MAMMALIAN TISSUE CULTURE CELLS

DNA-protein coacervates containing colloidal gold particles were readily phagocytized by strain L fibroblasts. During the subsequent digestion process, the gold particles served as markers which permitted the demonstration of the evolution of digestive vacuoles to multivesicular bodies and finally to dense bodies. Acid phosphatase and esterolytic activity was present in these structures. The hydrolytic enzymes were apparently brought to the phagocytotic vacuoles in small vesicles originating in the Golgi region. These vesicles entered the vacuoles prior to the digestion of the coacervates and the appearance of positive cytochemical reactions. The cytoplasmic dense bodies frequently merged with the phagocytotic vacuoles. This was demonstrated by prelabeling the dense bodies with colloidal iron prior to phagocytosis of the coacervates. In addition, evidence is presented for the interrelationship of the phagocytotic and autophagic pathways.

Using alfalfa leaf meal as a supplement in late-gestation beef heifer and nursing beef calf diets

Two experiments were conducted to investigate using alfalfa leaf meal (ALM; 22% CP, DM basis) in beef cattle diets. In Exp. 1, a total of 24 late-gestation Angus heifers (initial BW 470 +/- 9 kg) were blocked by BW, calving date, and BCS to 1 of 4 dietary treatments in a randomized complete block design. All heifers were offered a basal hay diet (7.4% CP and 67.6% NDF, DM basis). Treatments were arranged as a 2 x 2 factorial consisting of CP supplied at 100 or 112.5% of the recommended daily intake using either soybean meal (SBM) or ALM as the supplemental protein source. Treatments were fed for an average of 100 d before calving. Total DMI was unaffected by supplemental protein source, although heifers consumed more (P < 0.001) ALM supplement than SBM supplement at the expense of hay and corn. Feeding 112.5% of recommended CP to heifers increased precalving rate of BW gain (P = 0.004) and DM digestibility (P = 0.003). Protein source did not affect DM digestibility (P = 0.17). Neither supplemental protein source nor protein amount affected changes in BCS or calving traits. In Exp. 2, replicates of treatments were conducted over 2 consecutive years at 2 locations in northern Minnesota to determine the effects of including ALM in creep-fed supplements on nursing calf performance, supplement BW gain efficiency (GF; BW gain over control/supplement intake), and cow performance. Treatments were control (no supplement), ALM supplement (58% ALM, as-fed basis), or a wheat middling- and soybean hull-based supplement (MIDD). Milk intake (estimated by the weigh-suckle-weigh technique) was similar among treatments. Creep-fed calves had greater (P < 0.001) ADG than control calves, whereas calves offered MIDD tended to have greater ADG (P = 0.05) than those offered ALM (1.38 vs. 1.30 kg/d, respectively). Calves offered MIDD had greater (P < 0.001) creep feed DMI than those offered ALM (2.6 vs. 1.3 kg/d, respectively). A year x treatment interaction was noted for GF (P = 0.02). In yr 1, GF for calves offered ALM was greater (P = 0.006) than GF for calves offered MIDD, but in yr 2, there were no differences. Alfalfa leaf meal may substitute for SBM in beef heifer wintering diets and conventional creep feed ingredients. When included in creep feed diets, ALM can result in slightly less ADG and less DMI, but supplement conversion efficiency may be increased.

SEPT9 gene sequencing analysis reveals recurrent mutations in hereditary neuralgic amyotrophy

BACKGROUND

Hereditary neuralgic amyotrophy (HNA) is an autosomal dominant disorder that manifests as recurrent, episodic, painful brachial neuropathies. A gene for HNA maps to chromosome 17q25.3 where mutations in SEPT9, encoding the septin-9 protein, have been identified.

OBJECTIVE

To determine the frequency and type of mutations in the SEPT9 gene in a new cohort of 42 unrelated HNA pedigrees.

METHODS

DNA sequencing of all exons and intron-exon boundaries for SEPT9 was carried out in an affected individual in each pedigree from our HNA cohort. Genotyping using microsatellite markers spanning the SEPT9 gene was also used to identify pedigrees with a previously reported founder haplotype.

RESULTS

Two missense mutations were found: c.262C>T (p.Arg88Trp) in seven HNA pedigrees and c.278C>T (p.Ser93Phe) in one HNA pedigree. Sequencing of other known exons in SEPT9 detected no additional disease-associated mutations. A founder haplotype, without defined mutations in SEPT9, was present in seven pedigrees.

CONCLUSIONS

We provide further evidence that mutation of the SEPT9 gene is the molecular basis of some cases of hereditary neuralgic amyotrophy (HNA). DNA sequencing of SEPT9 demonstrates a restricted set of mutations in this cohort of HNA pedigrees. Nonetheless, sequence analysis will have an important role in mutation detection in HNA. Additional techniques will be required to find SEPT9 mutations in an HNA founder haplotype and other pedigrees.

Transgenic mice expressing a human mutant beta1 thyroid receptor are hyperactive, impulsive, and inattentive

Attention deficit hyperactivity disorder (ADHD) is the most commonly diagnosed childhood psychiatric disorder. We have found that a transgenic mouse bearing a human mutant thyroid receptor (TRbeta1) expresses all of the defining symptoms of ADHD--inattention, hyperactivity, and impulsivity--as well as a 'paradoxical' response to methylphenidate (MPH). As with ADHD, the behavioral phenotypes expressed by the TRbeta transgenic mice are dynamic and sensitive to changes in environmental conditions, stress, and reinforcement. TRbeta transgenic mice are euthyroid except for a brief period during postnatal development, but the behavioral phenotypes, elevated dopamine turnover, and paradoxical response to MPH persist into adulthood. Thus, like the vast majority of children with ADHD, the TRbeta transgenic mice exhibit the symptoms of ADHD in the complete absence of thyroid abnormalities. This suggests that even transient perturbations in developmental thyroid homeostasis can have long-lasting behavioral and cognitive consequences, including producing the full spectrum of symptoms of ADHD.

Fixed-time insemination in peripuberal, lightweight replacement beef heifers after estrus synchronization with PGF2alpha and GnRH

Estrus synchronization contributes to optimizing the use of time, labor, and financial resources by shortening the calving season, in addition to increasing the uniformity of the calf crop. We determined whether acceptable pregnancy rates could be achieved after synchronization of ovulation and fixed-time artificial insemination (AI) in peripuberal replacement beef heifers using gonadotropin-releasing hormone (GnRH) and PGF2alpha. Crossbred heifers from two herds (MH, n=239; SS, n=330) were wintered at a single location. After a prebreeding examination revealed that 55 heifers had a reproductive tract score (RTS) of 1 (infantile reproductive tracts), they were culled and the remaining heifers were assigned randomly to one of three treatment groups: administration of 25mg PGF2alpha i.m. on Days -12 and 0 followed by estrus detection and insemination between 10 and 14 h after an observed estrus (Control; n=173); administration of 100 microg GnRH i.m. on Day -6, followed by 25 mg PGF2alpha i.m. on Day 0, then fixed-time AI and administration of 100 microg GnRH i.m. on Day +2 (GPG; n=172); and, treatment as for group GPG in addition to administration of 100 microg GnRH i.m. on Day -12 (GGPG; n=169). Bulls were introduced 10 days after AI for 60 days to breed heifers which did not conceive after AI (clean-up bulls). On Days -12, -6, and 0 transrectal ultrasonography was used to monitor ovarian structures in a subset of heifers (30 per treatment). At 30-35 days after AI, ultrasound was used to determine the presence of a viable fetus. Presence of a fetus and stage of pregnancy were determined via palpation per rectum 61-63 days after the conclusion of the breeding season. Heifers in the MH herd (309+/-1.9 kg) were heavier (P<0.001) than those in the SS herd (283+/-1.7 kg) at initiation of the breeding season. Synchronized pregnancy rates were greater (P<0.05) in GGPG (25.4%) and GPG (22.1%) than Control (12.7%) heifers. Pregnancy rates were 9, 21, 32, or 31% for heifers with RTS of 2, 3, 4, or 5, respectively. The average diameter of 22 follicles induced to ovulate in heifers treated with GnRH (GPG and GGPG treatments) was 14.2+/-0.8 mm (range=10.0-23.6 mm). In conclusion, a fixed-time ovulation synchronization program using GnRH and PGF2alpha improved pregnancy rates in peripuberal, lightweight replacement beef heifers.

Reflection on the history, coordination, and funding trends for U.S. public meat research: information to enhance resource allocation

A study was conducted to analyze resource allocation for public meat research in the United States and characterize the portfolio of meat research investments. Trends in the amount of public resources provided for meat research (beef, pork, lamb, and poultry) were analyzed for fiscal years 1980, 1985, 1990, 1995, and 1997. An in-depth analysis was conducted for data from fiscal year 1998 to characterize the profile of the research portfolio. Funding levels and scientist-year equivalents were aggregated to represent the measures of resource allocation for three mutually exclusive research categories: 1) meat quality, 2) food safety, and 3) product development and processing. Data for the 1998 profile analysis were derived from a computer search based on the combination of key words and research classification codes to avoid duplication and cluster research projects. Individual research projects were individually reviewed and a percentage was assigned to four mutually exclusive research categories: 1) meat quality, 2) food safety, 3) product development and processing, and 4) marketing. As meat research evolved over the past century, considerable efforts were expended by researchers and administrators to ensure the coordination of research and program relevance. This is demonstrated by the establishment of numerous multistate research committees. Total funding for meat science increased only modestly when adjusted for inflation during the two decades of this study; however, notable changes occurred in the distribution of resources in the portfolio. Funding for meat quality and product development and processing remained virtually unchanged when adjusted for inflation, whereas funding for food safety increased considerably. The total number of scientists conducting meat research remained virtually unchanged during the period, but the proportion allocated to food safety research increased substantially. The federal portion of total funding decreased from 61.3% to 51.6% between 1980 and 1997, whereas the percentage from both state appropriations and private sources increased. Modifications in research emphasis were influenced by industry problems such as meat quality, public perceptions about food safety, the availability of research funding, scientific advances occurring in molecular biology and genetic manipulation, and the changing meat industry. The information in this paper provides administrators and researchers the opportunity to make better informed decisions about resource allocation for meat research.

Phylogenetic analysis and trait evolution in Australian lineages of drywood termites (Isoptera, Kalotermitidae)

A phylogenetic analysis of Australian drywood termites (Isoptera, Kalotermitidae) based on partial sequence from the cytochrome oxidase II (COII) and cytochrome b genes is presented. In addition to providing new information on the evolutionary relationships among 25 species from seven genera, we evaluate the relative likelihoods of alternative topological hypotheses, including those derived from morphology-based classifications. We also test the applicability of a molecular clock for estimating the age of the Kalotermitidae and infer the evolution of species-specific variation for habitat type and soldier caste phragmosis by mapping this information onto the independently derived phylogeny. Maximum-likelihood analysis of both nucleotide and protein sequences from a multigene data set jointly support a single topology, which is shown to be the best estimate of the true phylogeny among the alternatives tested. Our results support the monophyly of all genera but question the discrimination between Procryptotermes and Cryptotermes. A basal dichotomy among generic groups suggests two principle lines of divergence within the family. Intergeneric relationships show mixed congruence to previous proposals, resulting in one morphology-based classification being rejected. A molecular clock hypothesis is not supported due to significant among-lineage rate heterogeneity in the COII gene. Patterns revealed through trait mapping suggest that the most recently diverged taxa tend to occupy the driest habitats and that these same taxa reflect a defensive transition away from large mandibulate soldiers toward small phragmotic soldiers. The association between habitat and defensibility supports the hypothesis that these two characters have been tightly linked throughout the social diversification of termites.

Cause of metabolic acidosis in prolonged surgery

OBJECTIVE

The intraoperative development of metabolic acidosis is frequently attributed to hypovolemia, tissue hypoperfusion, and lactic acidosis. In this study, dilutional acidosis was evaluated as a possible mechanism for the routine development of intraoperative acidosis in noncardiac, nonvascular surgery patients.

DESIGN

Prospective, observational study.

SETTING

University-affiliated Veteran's Affairs Medical Center and a staff model, health maintenance organization hospital.

PATIENTS

Twelve patients undergoing prolonged surgical procedures expected to last > or = 4 hrs were enrolled in the study.

INTERVENTIONS

Perioperative management was based on the judgment of the attending anesthesiologist and surgeon without knowledge of the study's intent.

MEASUREMENTS AND MAIN RESULTS

Arterial blood gas parameters, serum electrolytes, and urine electrolytes were measured pre- and postoperatively. Pulmonary artery catheters were placed for hemodynamic measurement and oxygen delivery calculations. Plasma volume was measured both pre- and postoperatively, using the Evans blue dye dilution technique. Although significant changes in lactate level (1.1 +/- 0.6-1.8 +/- 1.0) occurred, the change was not large enough to explain the degree of change in base excess (0.8 +/- 2.3 to -2.7 +/- 2.9). Chloride levels significantly increased (106 +/- 3-110 +/- 5) with a correlation (r2 = .92; p < .0001) between the degree of change in chloride and the degree of change in base excess. Plasma volume did not change. Furthermore, a correlation between the volume of normal saline administered and the change in base excess was found (r2 = .86; p < .0001), although no correlation was found with Ringer's lactate solution. An even stronger correlation was noted when the total chloride amount administered was compared with the change in base excess (r2 = .93; p < .0001).

CONCLUSIONS

In this patient population, a common source of increasing base deficit is related to chloride administration. The largest source of chloride is usually normal saline. Classically, dilutional acidosis would explain the predominance of this acidotic change; however, no increase in plasma volume occurred. The absence of plasma volume change would suggest that the mechanism postulated to result in dilutional acidosis is incomplete. The common treatment of administering more fluid for intraoperative acidosis may be inappropriate, may have caused the acidosis, and may further exacerbate the acidosis. Chloride levels should be assessed whenever a metabolic acidosis is seen perioperatively.

The role of the vomeronasal organ of crotalines (Reptilia: Serpentes: Viperidae) in predator detection

Most reptiles and mammals, with the exceptions of crocodilians, aquatic mammals and some primates, have a functional vomeronasal organ that detects and perceives semi-volatile chemicals in the environment. This organ is used in detection of prey and is also important for recognition of conspecifics and potential predators. We tested eight species of North American pit vipers for behavioural responses to an ophiophagous (snake-eating) predator, the common kingsnake, Lampropeltis getula. Kingsnakes have a substance in their skin that is recognized by crotalines, which react with a series of defensive responses including, but not limited to, avoidance, fleeing, body bridging and head hiding. The vomeronasal duct of the pit vipers was sutured closed to determine the role of this organ in detection of kingsnakes. Pit vipers with intact and sutured vomeronasal ducts were tested in a neutral cage with a kingsnake and monitored for behavioural responses. Results demonstrated that the vomeronasal organ is important in the recognition of kingsnakes by pit vipers and raises doubts that any other sense plays a major role in this behaviour. Copyright 1999 The Association for the Study of Animal Behaviour.

Influence of radical prostatectomy on serum hormone levels

PURPOSE

The influence of radical prostatectomy on the hypothalamic pituitary axis has not been well studied. It is also unclear how alterations in serum androgen levels that result from surgical removal of the prostate might influence the recovery of libido and sexual function following radical prostatectomy. We determined the influence of radical prostatectomy on the hypothalamic pituitary testicular axis of 63 men with clinically localized prostate cancer treated only with radical prostatectomy.

MATERIALS AND METHODS

A total of 63 healthy men 43 to 67 years old were enrolled in this prospective study. Phlebotomy was performed immediately before and 1 year following radical retropubic prostatectomy. Sera were stored frozen and analyzed as a group at the end of the study. We measured serum testosterone, percent free testosterone, dihydrotestosterone (DHT), estradiol, luteinizing hormone (LH), follicle-stimulating hormone (FSH), sex hormone binding globulin and prolactin.

RESULTS

Following radical prostatectomy there was a statistically significant increase in serum testosterone, free testosterone, estradiol, LH and FSH (p <0.0001), and statistically significant decrease in serum DHT (p <0.0001). No difference was noted in serum sex hormone binding globulin or prolactin levels. There was no statistically significant correlation between any serum hormone and sample storage time, patient age or prostate volume that could limit potential bias in study design. Serum hormone changes did not correlate with pathological stage or histological grade for this group of patients.

CONCLUSIONS

Radical prostatectomy influences the hypothalamic pituitary axis by increasing serum testosterone, percent free testosterone, estradiol, LH and FSH while decreasing serum DHT levels. These findings suggest that the sexual dysfunction associated with radical prostatectomy cannot be explained by androgen deficiency alone. These data further suggest that the normal prostate and/or prostate neoplasm could secrete a substance or substances that give negative feedback control to pituitary gonadotropin secretion. Further investigation is warranted to identify this substance or substances.

RoBo-1, a novel member of the urokinase plasminogen activator receptor/CD59/Ly-6/snake toxin family selectively expressed in rat bone and growth plate cartilage

Using differential display polymerase chain reaction, we cloned a novel cDNA named RoBo-1 from rat tibia. RoBo-1 is abundantly expressed in bone, including the hypertrophic chondrocytes of the growth plate where cartilage is remodeled into bone. RoBo-1 mRNA expression increased in response to two modulators of bone metabolism, estradiol and intermittent mechanical loading, suggesting a role in bone homeostasis. The 1.6-kilobase cDNA encodes a 240-amino acid protein with a cysteine spacing pattern, suggesting that RoBo-1 is a novel member of the urokinase plasminogen activator receptor/CD59/Ly-6/snake toxin family. Furthermore, the C-terminal contains a glycosyl-phosphatidylinositol attachment site, suggesting that it is a cell surface protein similar to other mammalian members of this family. The strongest homology of RoBo-1 is to the snake serum-derived phospholipase A2 inhibitors, which uniquely contain two of the cysteine domains but are secreted proteins. Interestingly, RoBo-1 is likely the first membrane-anchored member of this family containing two cysteine domains. Thus, the tissue specificity, responsiveness to bone protective mediators, along with its relationship to the multifunctional urokinase plasminogen activator receptor/CD59/Ly-6/snake toxin family suggests that RoBo-1 may play a novel role in the growth or remodeling of bone.

Cyclic AMP signaling pathways are important in IL-1 beta transcriptional regulation

An intact cAMP response element (CRE) in the upstream regulatory sequence of IL-1 beta (-2755/-2762) has been shown to be essential for maintaining full IL-1 beta inducibility following treatment with LPS, PMA, or TNF-alpha. In the present study, using the recombinant plasmid pIL-1(4.0 kb)-chloramphenicol acetyltransferase, containing 4.0 kb of the IL-1 beta upstream regulatory sequence, we have demonstrated that dibutyryl cAMP treatment alone is capable of induction. Due to the critical nature of the CRE for the induction of IL-1 beta transcription, an effort was made to determine the importance of the cAMP signaling pathway(s) by determining whether CRE binding protein (CREB) and other CREB/activating transcription factor (ATF) family members that responded to cAMP were associated with the DNA-protein complex that forms at this site. Nuclear extracts prepared from LPS-treated THP-1 5A cells were fractionated by ammonium sulfate precipitation and heparin-Sepharose chromatography, and the resulting fractions were characterized in electrophoretic gel mobility shift assays. These purification steps resulted in an approximately 100-fold enrichment of the proteins binding to the CRE site. Western blot analysis of isolated fractions, using CREB- and ATF-1-specific Ab showed an increased level of these proteins in the enriched fractions. Tryptic digest and DNase I protection studies showed the presence of CREB protein in the complex at the CRE site. Supershift electrophoretic gel mobility shift assays and immunoprecipitation analysis provided further evidence that both CREB and ATF-1 are present in the complex. In addition, an increase in CREB phosphorylation was observed when THP-1 5A cells were treated with dibutyryl cAMP, LPS, or both. These studies confirm the importance of a cAMP signaling pathway(s) in the regulation of IL-1 beta at the transcriptional level.

Cyclic AMP signaling pathways are important in IL-1 beta transcriptional regulation

An intact cAMP response element (CRE) in the upstream regulatory sequence of IL-1 beta (-2755/-2762) has been shown to be essential for maintaining full IL-1 beta inducibility following treatment with LPS, PMA, or TNF-alpha. In the present study, using the recombinant plasmid pIL-1(4.0 kb)-chloramphenicol acetyltransferase, containing 4.0 kb of the IL-1 beta upstream regulatory sequence, we have demonstrated that dibutyryl cAMP treatment alone is capable of induction. Due to the critical nature of the CRE for the induction of IL-1 beta transcription, an effort was made to determine the importance of the cAMP signaling pathway(s) by determining whether CRE binding protein (CREB) and other CREB/activating transcription factor (ATF) family members that responded to cAMP were associated with the DNA-protein complex that forms at this site. Nuclear extracts prepared from LPS-treated THP-1 5A cells were fractionated by ammonium sulfate precipitation and heparin-Sepharose chromatography, and the resulting fractions were characterized in electrophoretic gel mobility shift assays. These purification steps resulted in an approximately 100-fold enrichment of the proteins binding to the CRE site. Western blot analysis of isolated fractions, using CREB- and ATF-1-specific Ab showed an increased level of these proteins in the enriched fractions. Tryptic digest and DNase I protection studies showed the presence of CREB protein in the complex at the CRE site. Supershift electrophoretic gel mobility shift assays and immunoprecipitation analysis provided further evidence that both CREB and ATF-1 are present in the complex. In addition, an increase in CREB phosphorylation was observed when THP-1 5A cells were treated with dibutyryl cAMP, LPS, or both. These studies confirm the importance of a cAMP signaling pathway(s) in the regulation of IL-1 beta at the transcriptional level.

MR imaging of breast implants

Magnetic resonance (MR) images of 57 implants in 32 women were reviewed for possible complications. Spin-echo T2-weighted MR imaging of one or both breasts was performed with dedicated breast coils in axial, coronal, and sagittal planes. At surgery in 19 patients, MR evaluation for rupture correlated in 17 cases (two false-negative ruptures). Implant ruptures were seen at surgery in 15 of the 19 patients. Nine ruptures involved single-lumen implants: Six were ruptured within the fibrous capsule that normally forms around the foreign implant (intracapsular rupture [two were seen only at surgery]), and three were ruptured beyond this fibrous capsule into the soft tissues (extracapsular rupture). Five ruptures involved double-lumen implants, in which only the outer lumen had ruptured, and one involved a single-lumen saline implant that had completely collapsed. Additional complications of capsule formation and infection were suggested in two implants, and infection was suggested in one. The MR imaging appearances of the various types of implants as well as their complications are presented.

Evaluation of immunoperoxidase techniques to detect Rickettsia rickettsii in fixed tissue sections

Standard immunoperoxidase techniques were evaluated in the diagnosis of Rocky Mountain spotted fever (RMSF). Formalin-fixed, paraffin-embedded tissue was tested to detect Rickettsia rickettsii using the same antibody provided by the Centers for Disease Control and Prevention that is used for direct immunofluorescence (DIF). Tissues from 23 patients with suspected RMSF were divided: some were snap-frozen for DIF; the remainder were fixed in formalin, processed routinely, and embedded in paraffin for immunoperoxidase and hematoxylin and eosin staining. Ten patients were ultimately determined to have RMSF; in nine of these patients, both DIF and immunoperoxidase staining were positive for R rickettsii. There were no discrepancies, positive or negative, between the two methods. In the one case with a false-negative result by both methods, the patient had received antirickettsial antibiotics 72 hours before the biopsy was performed. These data demonstrate that the immunoperoxidase technique is effective in diagnosing RMSF and may be applied to cases retrospectively.

An immunohistochemical study of perianal Paget's disease. Possible origins and clinical implications

The histogenesis of perianal Paget's disease is controversial. A clinical and pathologic study was done of a patient with a history of adenocarcinoma of the rectum for whom a subsequent diagnosis of perianal Paget's disease was the sole manifestation of recurrent rectal cancer. Immunohistochemical techniques were used to compare and contrast the original rectal adenocarcinoma with the subsequent perianal skin recurrence confined to the epidermis. Both the rectal adenocarcinoma and the Paget's cells were positive for cytokeratin, epithelial membrane antigen, B72.3, and carcinoembryonic antigen and negative for gross cystic disease fluid protein-15, Leu-M1, CA 125, and S-100 protein. These findings, their relevance to the histogenesis of perianal Paget's disease, and the possible clinical implications are discussed.

Improved lung preservation with cold air storage

Conventional topical slush cooling limits lung transport to 4 to 6 hours. For this canine study of an alternate air cooling system, 37 canine lungs were removed: 24 were placed in plastic bags, and inserted in a Transplanthermm container at core air temperatures (n = 6 lungs each) of (A) 4 degrees C, (B) 8 degrees C, (C) 12 degrees C, and (D) 20 degrees C; 6 were stored conventionally in ice slush (E); and 7 were transplanted immediately (F). After 8 hours, the stored lungs were transplanted and the contralateral pulmonary artery was ligated. Survival, arterial oxygen tension, and extravascular lung water were monitored at 15 minutes and every hour for 4 hours. Four-hour survival was 100% in groups A, B, and F; 83% in group C, 50% in group D, and 17% in group E. The mean arterial oxygen tension at 1 hour was lower in group E (6.4 +/- 2.4 kPa) than in group A (39.8 +/- 13.2 kPa) (p = 0.0002) or in group F (42.0 +/- 16.2 kPa) (p = 0.0035). Extravascular lung water in group E was higher at 15 minutes (15.44 +/- 5.63 mL/kg) than in group A (3.76 +/- 0.63 mL/kg) (p = 0.0001) and group F (4.69 +/- 1.65 mL/kg) (p = 0.003). Cold air storage appears to provide better lung preservation than hypothermic immersion in ice slush.

Effect of desmopressin on vein graft patency in a microvascular model

Desmopressin acetate decreases blood loss after cardiac surgery by activating platelets. We studied whether this effect was detrimental to small-caliber vein grafts in rats. Thirty minutes before femoral artery grafting with 0.75-mm-diameter reverse autogenous saphenous vein grafts, 20 rats received desmopressin acetate intravenously at 1.0 micrograms/kg over 10 minutes, and 20 control rats received normal saline intravenously over 10 minutes. In each group, 10 rats received a 6-mm-long graft and 10 an 18-mm-long graft. Graft patency was evaluated at 20 minutes, 24 hours, and 30 days. Intimal thickening was assessed by light and scanning electron microscopy. At 30 days, 9 short grafts and 8 long grafts in the desmopressin-treated group were patent, whereas only 8 short control grafts and only 6 long control grafts were patent. Intimal thickening and platelet deposition were the same in both groups. These data show no detrimental effects of desmopressin acetate on saphenous vein graft patency.

In vivo clearance of low density lipoprotein in pigeons occurs by a receptor-like mechanism that is not down-regulated by cholesterol feeding

The contribution of receptor-dependent and receptor-independent mechanisms for low density lipoprotein (LDL) clearance in vivo was determined in White Carneau and Show Racer pigeons fed either cholesterol free or cholesterol containing diets. The methylation of pigeon LDL resulted in the inhibition of recognition by the LDL receptor which allowed its use as a tracer of receptor-independent clearance. The fractional catabolic rate (FCR) of radiolabeled LDL in 20 control pigeons (means +/- S.E., 0.277 +/- 0.013 pools/h) was approximately seven times faster than for methylated LDL indicating that 86% of the total LDL clearance occurred by a receptor-mediated process. Total LDL clearance was reduced by 27% (FCR = 0.202 +/- 0.012 pools/h) in 14 cholesterol-fed pigeons, but receptor-mediated mechanisms were still responsible for 80% of the total LDL clearance. LDL uptake by individual tissues was measured using the residualizing label 125I-tyramine cellobiose. The liver was the primary site of LDL clearance in both control and cholesterol-fed birds. LDL receptors were active in every tissue examined and accounted for over 85% of the LDL clearance in the liver and over 90% in the adrenal gland. Consistent with the whole body LDL clearance findings, cholesterol-feeding did not significantly reduce receptor-mediated clearance of 125I-tyramine cellobiose-LDL by the liver or any of the other tissues. Hepatic sterol synthesis, however, was reduced by greater than 90% in cholesterol-fed animals. These data are consistent with the conclusion that LDL clearance in vivo in pigeons is mediated primarily by an LDL receptor-like mechanism that shows little down-regulation with hypercholesterolemia even though cholesterol synthesis is efficiently down-regulated.

A revision of the Termes-Capritermes branch of the Termitinae in Australia (Isoptera : Termitidae)

The Australian genera belonging to the Termes-Capritermes branch of the Termitinae are revised. Termes fatalis Linnaeus, the type species of Termes Linnaeus, is redescribed and a neotype soldier designated. Eight new genera and 27 new species are described, 18 species presently assigned to the genus Termes are transferred to other genera, Pericapritermes Silvestri is recorded from Australia for the first time. The phylogeny of the group is discussed and the general biology summarised. A key to the genera and species is given. The Australian genera and species are: Xylochomitermes, gen. nov., X. aspinosus, sp. nov., X. melvillensis (Hill), comb. nov., X. occidualis (Gay), comb. nov., X. punctillus, sp, nov., X. reductus (Gay), comb. nov., X. tomentosus (Gay), comb. nov.; Hesperotermes Gay, H. infrequens (Hill); Apsenterotermes, gen. nov., A. aspersus, sp. nov., A. declinatus, sp. nov., A. iridipennis (Gay), comb. nov., A. improcerus, sp. nov., A. stenopronos, sp. nov.; Ephelotermes, gen. nov., E. argutus (Hill), comb. nov., E. cheeli (Mjoberg), comb. nov., E. melachoma, sp. nov., E. paleatus sp. nov., E. persimilis (Gay), comb. nov., E. taylori (Hill), comb. nov.; Ekphysotermes Gay, E. jarmuranus (Hill), comb. nov., E. kalgoorliensis (Hill), E. ocellaris (Mjoberg), E. pelatus (Hill), E. percomis (Hill); Cristatitermes, gen. nov., C. arenicola, sp. nov., C. barretti, sp. nov., C. carinatus, sp. nov., C. froggatti (Hill), comb. nov., C. pineaformis, sp. nov., C. tutulatus, sp. nov.; Lophotermes, gen. nov., L. aduncus, sp. nov., L. brevicephalus, sp. nov., L. crinitus, sp. nov., L. leptognathus, sp. nov., L. parvicornis, sp. nov., L. pectinatus, sp. nov., L. pusillus, sp, nov., L. quadratus (Hill), comb. nov., L. septentrionalis (Hill), comb. nov.; Saxatilitermes, gen. nov., S. saxatilis, sp. nov.; Hapsidotermes, gen. nov., H. harrisi (Mjöberg), comb. nov., H. labellus, sp. nov., H. longius, sp. nov., H. maideni (Mjoberg), comb. nov., H. orbus (Hill), comb. nov.; Macrognathotermes, gen. nov., M. broomensis (Mjöberg), comb. nov., M. errator, sp. nov., M. prolatus, sp. nov., M. sunteri (Hill), comb. nov.; Paracapritermes Hill, P. kraepelinii (Silvestri), P. primus Hill, P. prolixus, sp. nov., P. secundus, sp. nov.; Protocapriterrnes Holmgren, P. krisiformis (Froggatt); Pericapritermes Silvestri, Pericapritermes sp.

Acquired renal cystic disease in end-stage renal disease: an autopsy study of 155 cases

Autopsy reports on 155 successive end-stage renal disease (ESRD) patients and 147 control patients without ESRD, matched for age, race and gender, were collected. Cystic transformation of the kidneys was noted in 58% of the ESRD patients and 13.6% of the control patients. There were 25 ESRD patients with renal adenoma and 3 with renal cell carcinoma. The single best predictor of cystic transformation or tumorous degeneration was patient's age. A statistically significant association between cystic transformation and gender, as well as the cause of ESRD, was also found. In contrast to previous reports we were unable to document a strong association between the incidence of either cystic transformation or tumorous degeneration with the duration of dialysis, nor did these two parameters correlate with mode of dialysis. We suggest that cystic transformation of the kidneys in ESRD is related to age and renal failure per se, is not strongly associated with duration of dialysis and is independent of mode of dialysis. Concomitant tumorous degeneration was frequent, but this was usually an incidental autopsy finding. Renal malignancy was uncommon and metastases were absent.

Inhibitors of sterol synthesis. Studies of the metabolism of 5 alpha-cholest-8(14)-en-3 beta-ol-15-one in Chinese hamster ovary cells and its effects on activities of early enzymes in cholesterol biosynthesis

The metabolism of [2,4-3H]5 alpha-cholest-8(14)-en-3 beta-ol-15-one (I) has been studied in Chinese hamster ovary (CHO-K1) cells which were maintained in a lipid-deficient medium. The incorporation of I into the cells was linear with respect to sterol concentration in the medium over the ranges of concentrations studied and was more than 3.5 times that of the uptake of cholesterol. The results of detailed chromatographic analyses of the lipids recovered from the cells after 6 h of incubation with [2,4-3H]I (0.5 microM or 6.0 microM) indicated that most of the 3H was associated with free I. Considerably lesser amounts of the 3H was associated with esters of I. No formation of [3H]cholesterol or [3H]cholesteryl esters (or other C27 monohydroxysterols) from labeled I was observed. The labeled material with the chromatographic behavior of the esters of I gave, after mild alkaline hydrolysis, the free 15-ketosterol which was characterized by the results of chromatographic and cocrystallization studies. Upon transfer of the CHO-K1 cells from a culture medium containing 8% newborn calf serum to the same medium containing 8% lipid-deficient newborn calf serum, increases in the levels of activity of cytosolic acetoacetyl-CoA thiolase and 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) synthase and of HMG-CoA reductase were observed. These increases were blocked by the addition of I at a concentration of 1.0 microM. I (1.0 microM) also caused a decrease in the levels of activity of the three enzymes in cells previously grown in medium containing lipid-deficient serum. These results demonstrate that I not only affects the enzymatic reduction of HMG-CoA but also the enzymatic formation of this key intermediate in cholesterol biosynthesis.

Inhibitors of sterol synthesis. Effects of dietary 5 alpha-cholest-8(14)-en-3 beta-ol-15-one on early enzymes in hepatic cholesterol biosynthesis

The effects of dietary administration (0.1% in diet for 8 days) of 5 alpha-cholest-8(14)-en-3 beta-ol-15-one on the levels of activity of cytosolic acetoacetyl coenzyme A thiolase, 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) synthase, and microsomal HMG-CoA reductase in liver have been studied in male Sprague-Dawley rats. Significant increases in the levels of activity of acetoacetyl-CoA thiolase and of HMG-CoA synthase were observed. The levels of microsomal HMG-CoA reductase activity were increased, relative to pair-fed control animals, in three experiments and increased, relative to ad libitum control animals, in one of three experiments. When compared with other agents for which the primary mode of action is an inhibition of the intestinal absorption of cholesterol, the magnitude of the increases in the levels of hepatic microsomal HMG-CoA reductase activity in the 15-ketosterol-fed rats was considerably smaller. In view of the previously described marked activity of the 15-ketosterol in the inhibition of the intestinal absorption of cholesterol, as well as its known effects in lowering HMG-CoA reductase activity in mammalian cells in culture, it is proposed that the 15-ketosterol may suppress the elevated levels of hepatic microsomal HMG-CoA reductase activity induced by the reduced delivery of cholesterol to liver as a consequence of the inhibition of the intestinal absorption of cholesterol.

5 alpha-cholest-8(14)-en-3 beta-ol-15-one. A competitive substrate for acyl coenzyme A:cholesterol acyl transferase

5 alpha-Cholest-8(14)-en-3 beta-ol-15-one, a potent inhibitor of cholesterol biosynthesis with hypocholesterolemic activity, has been found to serve as an efficient substrate for acyl CoA:cholesterol acyl transferase of rat hepatic and jejunal microsomes and to inhibit the esterification of cholesterol. Concentrations required to give 50% inhibition of cholesterol ester formation in liver and jejunal microsomes were approximately 10 microM and approximately 3 microM, respectively.

CT findings in complications of acquired renal cystic disease

A 42-year-old man with end-stage renal disease developed acquired renal cystic disease. The left kidney underwent tumorous degeneration necessitating nephrectomy. Eight months later acute hemorrhagic renal cyst rupture culminated in right nephrectomy.

Evidence for the existence of a lateral cervical nucleus in mice, guinea pigs, and rabbits

The lateral cervical nucleus of carnivores is large and is thought to play a prominent role in somatosensory processing. In contrast, early studies indicated that rats, mice, guinea pigs, and rabbits did not have a lateral cervical nucleus. However, we reported the existence of a lateral cervical nucleus in rats as a result of studies using retrograde transport techniques. In the present study, similar techniques were used to examine the possibility that early studies also overlooked the lateral cervical nucleus in mice, guinea pigs, and rabbits. In each of these species, a retrograde tracer was injected into the thalamus. These injections labeled a small number of neurons contralaterally in the dorsal part of the lateral funiculi of rostral cervical segments. Mice had the greatest number of neurons projecting from the lateral cervical nucleus to the thalamus, and rabbits had the fewest.

Lupus lung

The morphologic findings from 18 autopsy lungs of systemic lupus erythematosus were studied. Each case revealed varying degrees of pleuropulmonary disease. A universal feature was visceral pleural thickening, while findings present in more than one half of the cases included pulmonary congestion (17/18) and edema (15/18), pleural adhesions (11/18) and pleural effusions (10/18) and intraalveolar hemorrhage (10/18). Also seen were bronchopneumonia (9/18), interstitial fibrosis (6/18), cytomegalovirus infection (3/18), interstitial pneumonitis (2/18), hyaline membranes (2/18), and acute vasculitis (1/18) and pleuritis (1/18). These results, together with those of previously reported studies of lupus lung, establish that although certain characteristic pleuropulmonary disease processes are frequently found at autopsy, none is a highly specific marker for the disease.

Purification and crystallization of mammalian lens gamma-crystallins

Monomeric crystallins, beta s and several members of the gamma-crystallin family, occur in different relative proportions in a way which is related to the age of the lens cells. Methods of purification of large amounts of these different low molecular weight protein components from young and old bovine lenses are described along with details of crystallization of several gamma-fractions. Purification procedures have been developed for rabbit gamma-crystallins. The chromatographic methods achieve separation of several bovine and rabbit gamma-crystallins which have very similar electrophoretic mobilities. However, on storage, many electrophoretic variants are generated from some of these fractions.

Fetal iron balance in the rat

Maternal and fetal iron balance through pregnancy was examined in the rat. The 20th day was selected for detailed study because of the peak iron requirements at that time. The standard diet provided a borderline iron supply to the fetus due to the limited availability of its iron for absorption. When a more available form of iron was used, normal fetal development occurred over a range of dietary iron content from 16 to 2500 mg/kg. At a level of 5 to 8 mg/kg, there was attrition of placental tissues with frequent fetal death and resorption. When the iron-deficient pregnancy was sustained, both maternal and fetal iron deficiency were present. At progressively higher levels of dietary iron, feto-placental iron content was constant despite a progressive increase in maternal iron stores. Fetal iron supply appeared to be determined primarily by plasma iron concentration, and, at normal levels, about 25% of transferrin iron passing through the uterine vasculature, was removed by the intact placentas. Low levels of plasma iron resulted in damage to fetal tissues and reduced the capacity of placental tissues to take up iron. At high levels of plasma iron, plasma iron turnover initially increased 5-fold over basal levels in nonpregnant animals due to increased placental uptake. However, with continued hyperferremia, uptake was regulated so as to maintain fetal iron at a normal level. A comparison of these data with human iron requirements explained the occurrence of both maternal and fetal iron deficiency in the rat, but only maternal iron deficiency in the human.

Inhibitors of sterol synthesis. Differential effects of 14 alpha-hydroxymethyl-5 alpha-cholest-7-ene-3 beta, 15 alpha-diol and 14 alpha-hydroxymethyl-5 alpha-cholest-6-ene-3 beta, 15 alpha-diol on sterol synthesis in cell-free homogenates of rat liver

14 alpha-Hydroxymethyl-5 alpha-cholest-7-ene-3 beta, 15 alpha-diol and 14 alpha-hydroxymethyl-5 alpha-cholest-6-ene-3 beta, 15 alpha-diol have been shown to be potent inhibitors of the synthesis of digitonin-precipitable sterols in mouse L-cells and in primary cultures of fetal mouse liver cells and to cause a reduction in the levels of activity of 3-hydroxy-3-methylglutaryl-CoA reductase in the same cells (Schroepfer, G. J., Jr., Parish, E. J., Pascal, R. A., Jr., and Kandutsch, A. A. (1980) J. Lipid Res. 21, 571-584). In the present study, we have found that both sterols have a second, but distinct, site of action, distal to the formation of mevalonic acid. 14 alpha-Hydroxymethyl-5 alpha-cholest-7-ene-3 beta, 15 alpha-diol has been found to be a potent inhibitor of the synthesis of digitonin-precipitable sterols from labeled mevalonate in cell-free preparations of rat liver. This inhibition was accompanied by a striking accumulation of labeled lanosterol and 24,25-dihydrolanosterol. The latter sterols were fully characterized by the results of chromatographic and co-crystallization experiments. In contrast, 14 alpha-hydroxymethyl-5 alpha-cholest-6-ene-3 beta, 15 alpha-diol had only a slight effect on the synthesis of digitonin-precipitable sterols from labeled mevalonate in cell-free rat liver preparations. The delta 6-3 beta, 15 alpha, 32-triol had no apparent effect on the metabolism of lanosterol and 24,25-dihydrolanosterol but caused a substantial accumulation of labeled 5 alpha-cholest-8-en-3 beta-ol which was fully characterized by the results of chromatographic and co-crystallization experiments. These findings are compatible with a specific inhibition of the metabolism of lanosterol and 24,25-dihydrolanosterol by the delta 7-3 beta, 15 alpha, 32-triol and a specific inhibition of the delta 8 leads to delta 7 isomerase by the delta 6-3 beta, 15 alpha, 32-triol. [2,4]3H]14 alpha-Hydroxymethyl-5 alpha-cholest-7-ene-3 beta, 15 alpha-diol, prepared by chemical synthesis, was not convertible to cholesterol upon incubation, under aerobic conditions, with a cell-free homogenate preparation of rat liver. The labeled delta 7-3 beta, 15 alpha, 32-triol was, however, metabolized to several polar compounds.

Cycloheximide inhibits sterol biosynthesis in cell-free preparations of rat liver

Cycloheximide, frequently used as an inhibitor of protein synthesis in vivo and in vitro, has been found to cause a significant reduction of the synthesis of digitonin-precipitable sterols from acetate, but not from mevalonate, at a concentration of 1 mM in the 10,000 x g supernatant fraction of rat liver homogenate preparations. The results of studies of the metabolism of labeled leucine under the same conditions indicated that the effect of cycloheximide on sterol synthesis from acetate was not related to an effect of cycloheximide on protein synthesis. Preincubation of the 10,000 x g supernatant fraction of rat liver homogenates with cycloheximide (1 mM) caused a significant reduction in the levels of acetate thiokinase and hydroxymethylglutaryl-CoA synthase activities but not of acetoacetyl-CoA thiolase activity. Preincubation of the 100,000 x g supernatant fraction of rat liver homogenates with cycloheximide (1 mM or 0.3 mM) also caused a significant reduction of the levels of hydroxymethylglutaryl-CoA synthase activity. When cycloheximide (1 mM) was preincubated with the 100,000 x g supernatant fraction, a reduction in the level of acetate thiokinase activity was observed. Preincubation of rat liver microsomes with cycloheximide (1 mM and 3 mM) had no effect on the level of hydroxymethylglutaryl-CoA reductase activity. These results suggest that biological effects observed upon exposure of cells or tissues to high concentrations of cycloheximide may not be exclusively due to effects of the cycloheximide on the synthesis of protein.