Genetic Characteristics of Salmonella Isolates Recovered From Reused Broiler Litter Over Three Successive Flocks

Salmonella infections are a leading cause of bacterial food-borne illness worldwide. Infections are highly associated with the consumption of contaminated food, and in particular, chicken meat. The severity of Salmonella infections depends on the presence of antimicrobial resistance genes and virulence factors. While there are many studies which have investigated Salmonella strains isolated from postharvest chicken samples, there is a gap in our understanding of the genetic properties that influence the persistence of Salmonella in preharvest and in particular their makeup of antimicrobial resistance genes and virulence factors. We used whole genome sequencing and hierarchical clustering to characterize and classify the genetic diversity of Salmonella enterica isolates (n = 55) recovered from the litter of commercial broiler chicken raised in four colocated broiler houses of one integrated farm over three consecutive flocks. The chicken were raised under a newly adopted "No Antibiotics Ever" program, and copper sulfate was administered via drinking water. In-silico serovar prediction identified three S. enterica serovars: Enteritidis (n = 12), Kentucky (n = 40), and Senftenberg (n = 3). Antimicrobial susceptibility testing revealed that only one S. Kentucky isolate was resistant to streptomycin, while the remaining isolates were susceptible to all antibiotics tested. Metal resistance operons, including copper and silver, were identified chromosomally and on plasmids in serovar Senftenberg and Kentucky isolates, respectively, while serovar Enteritidis carried several virulence factors on plasmids. Serovar Kentucky isolates harboring metal resistance operons were the only Salmonella isolates recovered from the litter of third flock cohort. These results suggest that there might be environmental selection for Salmonella strains carrying plasmid-associated metal resistance and virulence genes, which could play a role in their persistence in litter.

Virulence factors and antimicrobial resistance profiles of Campylobacter isolates recovered from consecutively reused broiler litter

IMPORTANCE

Campylobacter is a leading cause of foodborne illness in the United States due to consumption of contaminated or mishandled food products, often associated with chicken meat. Campylobacter is common in the microbiota of avian and mammalian gut; however, acquisition of antimicrobial resistance genes (ARGs) and virulence factors (VFs) may result in strains that pose significant threat to public health. Although there are studies investigating the genetic diversity of Campylobacter strains isolated from post-harvest chicken samples, there are limited data on the genome characteristics of isolates recovered from preharvest broiler production. Here, we show that Campylobacter jejuni and Campylobacter coli differ in their carriage of antimicrobial resistance and virulence factors may also differ in their ability to persist in litter during consecutive grow-out of broiler flocks. We found that presence/absence of virulence factors needed for evasion of host defense mechanisms and gut colonization played an integral role in differentiating Campylobacter strains.

Antimicrobial susceptibility of Salmonella and Escherichia coli from equids sampled in the NAHMS 2015-16 equine study and association of management factors with resistance

Several studies have investigated antimicrobial resistance (AMR) in Salmonella spp. and Escherichia coli isolated from hospitalized horses, but studies conducted on community-based populations of equids are limited. The factors associated with AMR in these bacteria in the general horse population are not well understood. The primary objective of our study was to estimate the prevalence of Salmonella and describe antimicrobial susceptibility of Salmonella and E. coli from equids across the United States. The second objective was to identify associations between health management and biosecurity practices and AMR. Fecal samples submitted from 1357 equids on 199 operations were tested for Salmonella, identifying 27 positive samples with 29 isolates belonging to 18 serotypes. Fecal sample and operation-level prevalence of Salmonella was 2.0% (27/1357) and 7.0% (14/199), respectively. Most (25/29) isolates were pan-susceptible while four isolates exhibited resistance, three of which were multidrug resistant. Of the 721 samples cultured for E. coli, 85% (613/721) were positive. Eighty-six percent of the E. coli isolates recovered were pan-susceptible (529/612). Ten isolates were intermediate to one antimicrobial drug and susceptible to all others. Seventy-three E. coli isolates (11.9%, SE=1.3) were resistant to one or more antimicrobials, corresponding to a 33.0% (64/194) operation-level prevalence. Resistance to sulfonamide drugs was most common with 63 isolates (10.3%) resistant to sulfisoxazole, 57 of which (9.3%) were resistant to trimethoprim-sulfamethoxazole. MDR in E. coli was rare (1.8%, SE=0.5). Univariate and multivariable regression were used to evaluate associations between health management and biosecurity questionnaire items and AMR in E. coli. The outcome modeled was resistance to any of the 14 tested antimicrobials. Depending on the operation type, operations with greater than 20 resident equids were significantly associated with resistance. In addition, performance operations were significantly associated with resistance when compared to farm/ranch operations. Operations with feed containers that prevent fecal contamination and those that had treated any equids for illness or injury were associated with a lower AMR. The study results suggest that equids in the general population appear to pose low risk of shedding antimicrobial resistant strains of Salmonella and E. coli, and therefore low transmission potential to other equids, animals, humans, or the environment. However, it is prudent to practice good hand hygiene to prevent spread of Salmonella as well as AMR, and to protect both animal and human health. Despite study limitations, potential management factors that may influence prevalence and prevent spread of AMR shed by equids were identified.

Temporal dynamics of the cecal and litter microbiome of chickens raised in two separate broiler houses

In this study, we investigated the dynamics of the ceca and litter microbiome of chickens from post-hatch through pre-harvest. To achieve this, six hundred one-day old Cobb 500 broiler chicks were raised on floor pens for 49 days in two separate houses. We performed short-read and full-length sequencing of the bacterial 16S rRNA gene present in the meconium and in cecal and litter samples collected over the duration of the study. In addition, we determined the antimicrobial resistance (AMR) phenotype of Escherichia coli and Enterococcus spp. isolated from the meconium and the ceca of 49-day old chickens. We monitored the relative humidity, temperature, and ammonia in each house daily and the pH and moisture of litter samples weekly. The overall microbial community structure of the ceca and litter consistently changed throughout the course of the grow-out and correlated with some of the environmental parameters measured (p < 0.05). We found that the ceca and litter microbiome were similar in the two houses at the beginning of the experiment, but over time, the microbial community separated and differed between the houses. When we compared the environmental parameters in the two houses, we found no significant differences in the first half of the growth cycle (day 0-21), but morning temperature, morning humidity, and ammonia significantly differed (p < 0.05) between the two houses from day 22-49. Lastly, the prevalence of AMR in cecal E. coli isolates differed from meconium isolates (p < 0.001), while the AMR phenotype of cecal Enterococcus isolates differed between houses (p < 0.05).

Linking Predator Responses to Alkaloid Variability in Poison Frogs

Many chemically-defended/aposematic species rely on diet for sequestering the toxins with which they defend themselves. This dietary acquisition can lead to variable chemical defenses across space, as the community composition of chemical sources is likely to vary across the range of (an aposematic) species. We characterized the alkaloid content of two populations of the Dyeing Poison Frog (Dendrobates tinctorius) in northeastern French Guiana. Additionally, we conducted unpalatability experiments with naive predators, Blue Tits (Cyanistes caeruleus), using whole-skin secretion cocktails to assess how a model predator would respond to the defense of individuals from each population. While there was some overlap between the two D. tinctorius populations in terms of alkaloid content, our analysis revealed that these two populations are markedly distinct in terms of overall alkaloid profiles. Predator responses to skin secretions differed between the populations. We identified 15 candidate alkaloids (including three previously undescribed) in seven classes that are correlated with predator response in one frog population. We describe alkaloid profile differences between populations for D. tinctorius and provide a novel method for assessing unpalatability of skin secretions and identifying which toxins may contribute to the predator response. In one population, our results suggest 15 alkaloids that are implicated in predator aversive response. This method is the first step in identifying the causal link between alkaloids and behavioral responses of predators, and thus makes sense of how varying alkaloid combinations are capable of eliciting consistent behavioral responses, and eventually driving evolutionary change in aposematic characters (or characteristics).

Broiler house environment and litter management practices impose selective pressures on antimicrobial resistance genes and virulence factors of Campylobacter

Campylobacter infections are a leading cause of bacterial diarrhea in humans globally. Infections are due to consumption of contaminated food products and are highly associated with chicken meat, with chickens being an important reservoir for Campylobacter. Here, we characterized the genetic diversity of Campylobacter species detected in broiler chicken litter over three consecutive flocks and determined their antimicrobial resistance and virulence factor profiles. Antimicrobial susceptibility testing and whole genome sequencing were performed on Campylobacter jejuni (n = 39) and Campylobacter coli (n = 5) isolates. All C. jejuni isolates were susceptible to all antibiotics tested while C. coli (n =4) were resistant to only tetracycline and harbored the tetracycline-resistant ribosomal protection protein (TetO). Virulence factors differed within and across grow houses but were explained by the isolates' flock cohort, species and multilocus sequence type. Virulence factors involved in the ability to invade and colonize host tissues and evade host defenses were absent from flock cohort 3 C. jejuni isolates as compared to flock 1 and 2 isolates. Our results show that virulence factors and antimicrobial resistance genes differed by the isolates' multilocus sequence type and by the flock cohort they were present in. These data suggest that the house environment and litter management practices performed imposed selective pressures on antimicrobial resistance genes and virulence factors. In particular, the absence of key virulence factors within the final flock cohort 3 isolates suggests litter reuse selected for Campylobacter strains that are less likely to colonize the chicken host.

Litter Commensal Bacteria Can Limit the Horizontal Gene Transfer of Antimicrobial Resistance to Salmonella in Chickens

Fostering a "balanced" gut microbiome through the administration of beneficial microbes that can competitively exclude pathogens has gained a lot of attention and use in human and animal medicine. However, little is known about how microbes affect the horizontal gene transfer of antimicrobial resistance (AMR). To shed more light on this question, we challenged neonatal broiler chicks raised on reused broiler chicken litter-a complex environment made up of decomposing pine shavings, feces, uric acid, feathers, and feed-with Salmonella enterica serovar Heidelberg (S. Heidelberg), a model pathogen. Neonatal chicks challenged with S. Heidelberg and raised on reused litter were more resistant to S. Heidelberg cecal colonization than chicks grown on fresh litter. Furthermore, chicks grown on reused litter were at a lower risk of colonization with S. Heidelberg strains that encoded AMR on IncI1 plasmids. We used 16S rRNA gene sequencing and shotgun metagenomics to show that the major difference between chicks grown on fresh litter and those grown on reused litter was the microbiome harbored in the litter and ceca. The microbiome of reused litter samples was more uniform and enriched in functional pathways related to the biosynthesis of organic and antimicrobial molecules than that in fresh litter samples. We found that Escherichia coli was the main reservoir of plasmids encoding AMR and that the IncI1 plasmid was maintained at a significantly lower copy per cell in reused litter compared to fresh litter. These findings support the notion that commensal bacteria play an integral role in the horizontal transfer of plasmids encoding AMR to pathogens like Salmonella. IMPORTANCE Antimicrobial resistance spread is a worldwide health challenge, stemming in large part from the ability of microorganisms to share their genetic material through horizontal gene transfer. To address this issue, many countries and international organizations have adopted a One Health approach to curtail the proliferation of antimicrobial-resistant bacteria. This includes the removal and reduction of antibiotics used in food animal production and the development of alternatives to antibiotics. However, there is still a significant knowledge gap in our understanding of how resistance spreads in the absence of antibiotic selection and the role commensal bacteria play in reducing antibiotic resistance transfer. In this study, we show that commensal bacteria play a key role in reducing the horizontal gene transfer of antibiotic resistance to Salmonella, provide the identity of the bacterial species that potentially perform this function in broiler chickens, and also postulate the mechanism involved.

Hotspot mutations and ColE1 plasmids contribute to the fitness of Salmonella Heidelberg in poultry litter

Salmonella enterica subsp. enterica serovar Heidelberg (S. Heidelberg) is a clinically-important serovar linked to food-borne illness, and commonly isolated from poultry. Investigations of a large, multistate outbreak in the USA in 2013 identified poultry litter (PL) as an important extra-intestinal environment that may have selected for specific S. Heidelberg strains. Poultry litter is a mixture of bedding materials and chicken excreta that contains chicken gastrointestinal (GI) bacteria, undigested feed, feathers, and other materials of chicken origin. In this study, we performed a series of controlled laboratory experiments which assessed the microevolution of two S. Heidelberg strains (SH-2813 and SH-116) in PL previously used to raise 3 flocks of broiler chickens. The strains are closely related at the chromosome level, differing from the reference genome by 109 and 89 single nucleotide polymorphisms/InDels, respectively. Whole genome sequencing was performed on 86 isolates recovered after 0, 1, 7 and 14 days of microevolution in PL. Only strains carrying an IncX1 (37kb), 2 ColE1 (4 and 6kb) and 1 ColpVC (2kb) plasmids survived more than 7 days in PL. Competition experiments showed that carriage of these plasmids was associated with increased fitness. This increased fitness was associated with an increased copy number of IncX1 and ColE1 plasmids. Further, all Col plasmid-bearing strains had hotspot mutations in 37 loci on the chromosome and in 3 loci on the IncX1 plasmid. Additionally, we observed a decrease in susceptibility to tobramycin, kanamycin, gentamicin, neomycin and fosfomycin for Col plasmid-bearing strains. Our study demonstrates how positive selection from poultry litter can change the evolutionary path of S. Heidelberg.

Proposed Epidemiological Cutoff Values for Ceftriaxone, Cefepime, and Colistin in Salmonella

We tested a diverse set of 500 isolates of nontyphoidal Salmonella enterica subsp. enterica from various animal, food, and human clinical sources for susceptibility to antimicrobials currently lacking epidemiological cutoff values (ECOFFs) set by the European Committee on Antimicrobial Susceptibility Testing. A consortium of five different laboratories each tested 100 isolates, using broth microdilution panels containing twofold dilutions of ceftriaxone, cefepime, and colistin to determine the minimum inhibitory concentrations of each drug when tested against the Salmonella isolates. Based on the resulting data, new ECOFFs of 0.25 μg/mL for ceftriaxone, 0.12 μg/mL for cefepime, and 2 μg/mL for colistin have been proposed. These thresholds will aid in the identification of Salmonella that have phenotypically detectable resistance mechanisms to these important antimicrobials.

Rapid diagnostic evaluation of bronchial washings in patients with suspected coccidioidomycosis

Coccidioidomycosis is a regionally common fungal infection, primarily affecting the lung. While in the majority of cases the tempo of the disease allows for a more leisurely diagnostic plan, including multiple serologic tests and culture of respiratory secretions, occasionally, patients will present with rapidly progressive, life-threatening pulmonary illness, in whom there is an urgent need for rapid diagnosis. Evaluation of respiratory secretions including expectorated sputum as well as bronchial washings are frequently available or obtained for diagnosing pulmonary infiltrates. We compared the sensitivity of the Papanicolaou stain with 10% potassium hydroxide digestion (10% KOH) and with calcofluor white (cw). The Papanicolaou test performed the best and should be used in the evaluation of suspected patients with coccidioidomycosis.

Effects of epidermal growth factor and Clostridium difficile toxin B in a model of mucosal injury

Numerous factors have been advocated as being paramount to the development of necrotizing enterocolitis (NEC) including hypoxia, abnormal bacterial flora, and by products of enteral feedings. In an effort to better understand mechanisms involved at the level of the intestinal mucosal barrier the authors have chosen the CACO-2 cell line to model the neonatal intestinal epithelium. By growing CACO-2 cells in transwell inserts, the authors have investigated the ability of Clostridium difficile toxin B, epidermal growth factor (EGF), and a model of mechanical injury to alter transepithelial resistance of CACO-2 monolayers. The findings show that toxin B diminishes resistance in this setting, and EGF can alter that resistance drop.

Pyocolpos: diagnosis and treatment

Pyocolpos is a rare complication of hydrocolpos. Hydrocolpos usually presents during adolescence and is associated with an imperforate hymen. The following is a case of a 3-month-old girl with pyocolpos. Her history was significant for a urinary tract infection (UTI) at 7 weeks of age. The authors believe that her UTI was caused by urinary retention secondary to hydrocolpos. A complete evaluation may have prevented the complication of pyocolpos.

Tenidap inhibits replication of the human immunodeficiency virus-1 in cultured cells

Interleukin-6 (IL-6) may be important in the pathogenesis of HIV-1 because of its ability to induce HIV-1 expression in infected cells in vitro. Tenidap, a structurally and functionally novel antirheumatic drug affecting diverse biologic processes, has been shown to reduce IL-6 production by peripheral blood mononuclear cells stimulated with lipopolysaccharide. Tenidap also inhibits the activity of chloride-bicarbonate exchangers and causes acidification of the cytoplasmic compartment that is similar to the effect of the anion transport inhibitor UK5099. Furthermore, tenidap inhibits the cyclooxygenase-mediated pathway of arachidonic acid metabolism as do the nonsteroidal antiinflammatory drugs (NSAIDs). Here we show that tenidap decreased HIV-1 replication as measured by p24 core antigen in the acutely infected CD4+ T-lymphocyte lines H9 and Jurkat, in the acutely infected monocyte line U937, and in its chronically infected subclone U1.8/HIV. These effects were seen at concentrations in the range of 3 to 15 microM, well below those toxic to cells. The antiviral effects of tenidap may be independent of its ability to reduce IL-6 production based on the observations that these effects were as prominent in IL-6 nonresponsive lines as in IL-6 responsive lines and that the inhibition of p24 production was not reversed by exogenous IL-6.

Button device for antegrade enema in the treatment of incontinence and constipation

Antegrade enema through an appendicostomy is effective in improving the quality of life for patients with incontinence or severe constipation. For patients without an appendix, a conventional gastrostomy button was used to create a cecostomy (or ileostomy) that served as a port for the administration of enema solutions.

Anteriorly located anus: is constipation caused by abnormal location of the anus?

Anteriorly located anus (ALA) is frequently associated with severe constipation accompanied by defecation pain. Between 1988 and 1994, the authors treated 27 children (26 girls, 1 boy; age range, 0 to 11 years) to surgically correct ALA. The operation was performed according to a uniform protocol to longitudinally divide the internal sphincter muscle from the anal skin level to 2 cm above the dentate line on the posterior wall of the anorectum. For anal reconstruction, any of the conventional procedures was employed. Twenty-two of the 27 patients have had follow-up in our clinic for 12 months to 6 years (mean, 2.75 years). Eighteen are completely free of constipation and defecation pain and have regular spontaneous bowel movements. The other four require occasional use of enemas or laxatives. Anal incontinence did not occur in any patient. The results of this study suggest that abnormal function of the internal sphincter is the most likely cause of constipation or defecation pain in patients with ALA and that internal sphincterotomy is the cornerstone of surgical treatment.

Rejection after pediatric liver transplantation is not the limiting factor to survival

Liver transplantation became a very successful therapy when cyclosporin A was introduced as an immunosuppressive agent. In an effort to evaluate the contribution of difficult or uncontrolled allograft rejection to mortality, the authors determined the most important factors that limited survival after liver transplantation. Eighty-two children received a total of 94 liver transplants from January 1987 to the present. Patients' records were reviewed for complications that contributed to morbidity and mortality and to assess which complications were preventable. Twelve patients died (15%), nine within 6 weeks of liver transplantation. The chief contributing cause of death was hepatic artery thrombosis (one patient), brain death after liver transplantation for fulminant hepatic failure (two patients), primary allograft nonfunction or dysfunction (two patients), allograft rejection (three patients), or other problems (four patients). Overall, hepatic artery thrombosis occurred in 3.1%, allograft rejection in 57%, fulminant hepatic failure in 7%, and donor organ dysfunction in 7%. Allograft rejection contributed directly to the cause of death in three children (4%). The authors conclude that few deaths after pediatric liver transplantation are caused by failure of immunosuppression. A high survival rate can be achieved after transplantation by eliminating the correctable complications that most frequently occur in the early postoperative period.

Glycosylphosphatidylinositol-anchored CD4 supports human immunodeficiency virus type 1 replication, but not cytopathic effect, in T-cell transfectants

Despite equivalent p24 antigen production, HSB-2 T cells expressing glycosylphosphatidylinositol (GPi)-linked CD4 were productively infected without cell death or syncytium formation, unlike HSB-2 transfectants expressing wild-type CD4 (wtCD4). HSB-2 transfectants dually expressing wtCD4 and GPi-linked CD4 formed syncytia and died. Thus, wtCD4 expression is critical for human immunodeficiency virus cytopathic effect in HSB-2 transfectants.

Isolated liver transplantation for liver failure in patients with short bowel syndrome

The ultimate prognosis for patients with short bowel syndrome (SBS) has become progressively more favorable over the past decade. Advances in long-term total parenteral nutrition (TPN) have allowed this group of patients to meet nutritional needs while the process of intestinal adaptation occurs. Unfortunately, a subgroup of patients with SBS have hepatic failure (HF), most often secondary to TPN-induced cholestasis. Combined small bowel and liver transplantation (LT) offers a sound anatomic solution for cases of HF with SGS, but it remains experimental at this time. We propose that an isolated LT is a viable alternative mode of therapy for the patient with HF and SBS. The following characteristics were reviewed for five patients with SBS and HF who underwent LT: age at transplantation, weight, liver function, survival, intestinal length, volume of feeding before surgery, and current feeding tolerance and liver function. Four boys and one girl, aged 5.5 to 15 months (average, 11.9), had LT. The total bilirubin level at the time of transplantation was 14.4 to 37 mg/dL (average, 24.7). The patients weighed between 3.8 and 12 kg (average, 8.0), and feeding tolerance ranged from no enteric to complete enteric feeding (average, < 33% of calories by enteric feeding). Bowel loss was attributed to necrotizing enterocolitis in two cases, volvulus in two, and birth hypoxia in one. Bowel length ranged from 60 to 120 cm (average, 88.6). Four children (80%) survived LT, and the average follow-up period was 9.3 months. Three (75%) are home; one is on combined hyperalimentation and enteral feeding, and two are on full enteric feeding. One remains in a chronic care facility, on combined enteral and intravenous feeding. The average daily enteral feeding now comprises more than 70% of caloric requirements. The total bilirubin level is .6 to .8 mg/dL (average, .71). Isolated LT for HF in the patient with SBS effectively restores liver function, allowing time for further intestinal adaptation.

Monotherapy with cyclosporine for chronic immunosuppression in pediatric liver transplant recipients

Children who survive liver transplantation (LT) suffer the adverse effects of life-long immunosuppression. In an attempt to minimize these effects, we have instituted a program of tapering immunosuppression, resulting in chronic monotherapy for children after LT. Seventy-three children ages 4 months to 19 years received LT between January 1987 and December 1992. Patient survival was 85% (62/73), with graft survival of 73%, at one year. Triple therapy with prednisone, cyclosporine, and azathioprine begun at transplant was tapered as follows: 1-2 mg/kg prednisone at discharge was reduced by .2 mg/kg every 2 months until a .2 mg/kg total was reached. Alternate-day steroids (.2 mg/kg) were begun at 1 year and discontinued at 1.5 years. AZA (1 mg/kg) was begun posttransplant and discontinued after any serious viral illness or by 1 year. Currently 37 survivors are > 18 months post-LT and were considered candidates for monotherapy. Monotherapy was attempted in 28 (76%), and 25 of these remain on monotherapy an average of 2 years later. All have normal liver function. After monotherapy and alternate-day steroids were achieved, 66% of children < 5th percentile for height at the time of transplant improved to greater than the 5th percentile. There were 3 (11%) patients who rejected while on monotherapy an average of 1.15 years after it was started. These patients had the following predisposing factors that decreased cyclosporine levels and led to rejection: common bile duct stricture, chronic and intermittent antibiotic administration for urinary tract infection, and noncompliance. In the 9 potential candidates not tapered to monotherapy, 6 have had recurrent acute or chronic rejection; 2 of these now receive FK506. We conclude that the majority of stable pediatric LT recipients may be safely tapered to chronic cyclosporine monotherapy. Increased growth is a major benefit of decreased steroid dosing in these children. Cyclosporine absorption and adequate levels are crucial for success of this approach.

Persistence of the circadian variation and altered response to hepatectomy of hepatic ornithine decarboxylase activity with malignant tumor burden

We measured the effect of MC-26 mouse colon cancers (of different sizes) on the circadian rhythm of hepatic ornithine decarboxylase (ODC) activity and hepatic ODC activity during the 24 hr after 60% hepatectomy. Tumor-free control mice showed a normal circadian rhythm of ODC activity with the highest levels at 1100 hr and the lowest levels at 2300 hr. The amplitude of the rhythm was diminished significantly in mice with a large tumor burden (3% of their body weight), and hepatic ODC activity was significantly less than in the tumor-free mice at every point during the 24 hr of the study. In mice with "early" tumors (0.3% of body weight), basal activity of ODC was normal and there was no reactive increase in activity following hepatectomy. In contrast, mice with "late" (3% of body weight) tumors had significantly lower basal ODC activities and the increase in ODC activity following hepatectomy was prolonged and exaggerated. We concluded that tumor burden is associated with abnormal ODC activity and that these differences are exaggerated after hepatectomy. Furthermore, although average ODC concentrations in tumor-bearing mice fell precipitously, the circadian rhythm in hepatic ODC persisted. This finding indicates early recognition by the host of tumor presence, which has a profound negative regulatory effect on hepatic ODC. Apparently, this effect does not impinge on circadian control mechanisms, indicating that these signals act independently.

Aging and the trophic effects of cholecystokinin, bombesin and pentagastrin on the rat pancreas

We examined the effect of age on the trophic response of the pancreas to chronic treatment with cholecystokinin (CCK), bombesin, or pentagastrin. Three age groups (3-, 12-, and 24-months) male F344 rats received saline; CCK-8 (5 ng/kg), bombesin (10 micrograms/kg), or pentagastrin (100 micrograms/kg) by intraperitoneal injection t.i.d. for 2 weeks. Rats were then killed and the pancreases excised, weighed, and assayed for DNA, RNA, protein, and polyamine (putrescine, spermidine, and spermine) concentrations and contents. We found that none of the treatments altered body weight at any age. All three hormones increased pancreas size and cell number in 3-month old rats, but by 12 months, all three had increased only pancreatic RNA content. Pancreatic spermidine concentration was decreased by all three hormone regimens in 3- but not in 12-month old rats, and pancreatic putrescine concentration and content were increased in 12-month old rats receiving all three hormones. There was no change in any parameter following any of the three hormones, tested at 24 months of age. We conclude that, at the dosages tested, the trophic response of pancreas to chronic administration of CCK, bombesin, and pentagastrin, which is normally present in young adult rats, is lost with aging.

The effect of somatostatin on 5-hydroxytryptamine release from a carcinoid tumor

One of the major manifestations of the carcinoid syndrome is secretory diarrhea thought to be due to overproduction of 5-hydroxytryptamine (5-HT). Synthetic somatostatin analogues have proved to be clinically effective in controlling this diarrhea. We have established a continuous cell line from a human pancreatic carcinoid tumor that secretes 5-HT. We examined the ability of the somatostatin analogue, SMS 201-995, to inhibit 5-HT release in vitro. Tumor cells were exposed to SMS 201-995 (10(-6) mol/L), pentagastrin (10(-9) mol/L), acetylcholine (10(-5) mol/L), and isoproterenol (10(-5) mol/L) alone and in combination; 5-HT release was assayed with high pressure liquid chromatography. We found that pentagastrin (6.43 +/- 0.64 ng/ml), isoproterenol (20.24 +/- 2.17 ng/ml), and acetylcholine (12.39 +/- 1.10 ng/ml) each stimulated release of 5-HT compared to control values (4.38 +/- 0.42 ng/ml). SMS 201-995 significantly reduced release of 5-HT in response to isoproterenol and acetylcholine but did not inhibit the effect of pentagastin. These data suggest that different agents do not act through the same pathway to stimulate 5-HT release from human pancreatic carcinoid cells.

Bone density distribution within the femoral head and neck. An examination by high-resolution computed tomography

The upper portions of three cadaveric femora were examined by high-resolution computed tomography. Analysis of the resulting images provided both quantitative and spatial distributions of bone density within the femoral head and neck. The information obtained provides new insights into aspects of proximal femoral architecture for both normal and osteoporotic bone. The study also points the way towards a clinical technique for measuring the material properties of proximal femoral bone.

Age-related changes in the abdominal aorta shown by computed tomography

A study of the computed tomographic appearances of the abdominal aorta in 257 patients confirms previous observations on the progressive increase in aortic diameter which occurs with advancing years. This progressive dilatation is more marked in males. No statistically significant difference was found in the age of onset of mural calcification between the sexes, although calcification was seen in more males than females aged 30-60 years. In the seventh and eighth decades annular calcification was seen more frequently in females. The normal values provided may be of help in the assessment of the diseased aorta.