Toxicity profiles and protective effects of antifreeze proteins from insect in mammalian models.

Antifreeze proteins (AFPs), found in many cold-adapted organisms, can protect them from cold and freezing damages and have thus been considered as additional protectants in current cold tissue preservation solutions that generally include electrolytes, osmotic agents, colloids and antioxidants, to reduce the loss of tissue viability associated with cold-preservation. Due to the lack of toxicity profile studies on AFPs, their inclusion in cold preservation solutions has been a trial-and-error process limiting the development of AFPs' application in cold preservation. To assess the feasibility of translating the technology of AFPs for mammalian cell cold or cryopreservation, we determined the toxicity profile of two highly active beetle AFPs, DAFP1 and TmAFP, from Dendroides canadensis and Tenebrio molitor in this study. Toxicity was examined on a panel of representative mammalian cell lines including testicular spermatogonial stem cells and Leydig cells, macrophages, and hepatocytes. Treatments with DAFP1 and TmAFP at up to 500 µg/mL for 48 and 72 h were safe in three of the cell lines, except for a 20% decrease in spermatogonia treated with TmAFP. However, both AFPs at 500 µg/mL or below reduced hepatocyte viability by 20-40% at 48 and 72 h. At 1000 µg/mL, DAFP1 and TmAFP reduced viability in most cell lines. While spermatogonia and Leydig cell functions were not affected by 1000 µg/mL DAFP1, this treatment induced inflammatory responses in macrophages. Adding 1000 µg/mL DAFP1 to rat kidneys stored at 4 °C for 48 h protected the tissues from cold-related damage, based on tissue morphology and gene and protein expression of two markers of kidney function. However, DAFP1 and TmAFP did not prevent the adverse effects of cold on kidneys over 72 h. Overall, DAFP1 is less toxic at high dose than TmAFP, and has potential for use in tissue preservation at doses up to 500 µg/mL. However, careful consideration must be taken due to the proinflammatory potential of DAFP1 on macrophages at higher doses and the heighten susceptibility of hepatocytes to both AFPs.

Integrated pest management strategies to sustain corn productivity.

The study was conducted to evaluate the economics and effectiveness of Trichogramma and earwigs in the suppression of corn borer and identify other corn pest associated during vegetative stage using light trapping. A Randomized Complete Block Design was used in laying out the experiments with five treatments as follows: Treatment 1-Control, Treatment 2-Trichogramma, Treatment 3-Earwigs, Treatment 4-Light Trapping and Treatment 5-Trichogramma + earwigs. Based on the analysis of variance it revealed highly significant variations among treatments with regards to number of parasitized and unparasitized egg mass of corn borer at 35 and 45 days after planting. In like manner, the damage assessment done by corn borer differed significantly at 35 and 45 days after planting. With regards to weight of green corn grains per sampling area, a highly significant differences was observed among the treatment means. The combination of Trichogramma and Earwigs showed high effectively in the field by exhibiting the highest computed yield per hectare and higher return of investment per peso invested.

A selective retinoid X receptor agonist bexarotene (LGD1069, targretin) inhibits angiogenesis and metastasis in solid tumours.

The present study determined the influence of a retinoid X receptor agonist bexarotene on angiogenesis and metastasis in solid tumours. In the experimental lung metastasis xenograft models, treatment with bexarotene inhibited the development of the lung tumour nodule formation compared to control. In vivo angiogenesis assay utilising gelfoam sponges, bexarotene reduced angiogenesis in sponges containing vascular endothelial growth factor, epidermal growth factor and basic fibroblast growth factor to various extent. To determine the basis of these observations, human breast and non-small-cell lung cancer cells were subjected to migration and invasion assays in the presence of bexarotene. Our data showed that bexarotene decrease migration and invasiveness of tumour cells in a dose-dependent manner. Furthermore, bexarotene inhibited angiogenesis by directly inhibiting human umbilical vein endothelial cell growth and indirectly inhibiting tumour cell-mediated migration of human umbilical vein endothelial cells through Matrigel matrix. Analysis of tumour-conditioned medium indicated that bexarotene decreased the secretion of angiogenic factors and matrix metalloproteinases and increased the tissue inhibitor of matrix metalloproteinases. The ability of bexarotene to inhibit angiogenesis and metastasis was dependent on activation of its heterodimerisation partner peroxisome proliferator-activated receptor gamma. Collectively, our results suggest a role of bexarotene in treatment of angiogenesis and metastasis in solid tumours.

Tuberculosis infection and disease in children living in households of Filipino patients with tuberculosis: a preliminary report.

SETTING: DOTS Clinic with a DOTS-Plus pilot project for the management of multidrug-resistant tuberculosis (MDR-TB) in a high burden country. OBJECTIVE: To determine the prevalence of tuberculosis (TB) infection and disease among pediatric household contacts of patients with pulmonary TB (PTB). DESIGN: Cross-sectional study. METHODOLOGY: One hundred and fifty-three children aged 0-15 years in the households of 62 bacteriologically confirmed PTB patients, including 44 with MDR-TB, were studied. BCG scars were noted, and tuberculin skin test (TST), screening chest radiography, and sputum or gastric aspirate smear and culture for Mycobacterium tuberculosis in those with radiographic findings suggestive of PTB were done. RESULTS: For children in this study, the prevalences of latent TB infection (LTBI), radiographically diagnosed pulmonary TB, and bacillary pulmonary TB were 69.2%, 3.3%, and 0.65%, respectively. Only age > or = 5 years was found to be a significant predictor of LTBI (OR 3.17, 95%CI 1.43-7.01). CONCLUSION: Contact investigation for active case-finding and early treatment of TB in children from households of patients with active PTB is essential for TB control. Further study on a more precise definition of TB infection and strategies for control in this population will be pursued.

Intraabdominal vancomycin-resistant enterococcus infections: the new threat.

GOALS: To determine the clinical course and outcome in patients with intraabdominal vancomycin-resistant enterococcus infections (VRE-A) and to identify probable risk factors for VRE-A. BACKGROUND: Vancomycin-resistant enterococcus is one of the most notable nosocomial emerging pathogens. The incidence is increasing, especially in the abdominal surgery setting. STUDY: A comparative study of patients with VRE-A and VRE infection in other sites (VRE-O) who were hospitalized for over 1 year. Fisher exact test and Student t test were used; a two-tailed p value of less than 0.05 was considered to be significant. RESULTS: Of 89 nine patients with VRE, six had VRE-A, 24 had VRE-O, and 59 had VRE colonization. The VRE-A group was comprised of one patient with an inoperable Klatskin tumor and biliary sepsis, one with acquired immune deficiency syndrome and an infected pancreatic pseudocyst, two with fecal peritonitis, and two with biliary sepsis after surgery for common bile duct stones. All six patients with VRE-A had recent surgery before VRE isolation, as compared with three in the VRE-O group (p = 0.0001). Despite adequate treatment with intravenous chloramphenicol, resulting in eradication of VRE in all six VRE-A cases, the mortality rate remained high at 50%. CONCLUSIONS: Vancomycin-resistant enterococcus should be recognized as an emerging nosocomial pathogen that causes potentially fatal intraabdominal infections in the postsurgical setting. However, the impact of treatment on ultimate outcome needs further evaluation.

Spontaneous fungal peritonitis (Candida glabrata) in a patient with cirrhosis.

We report a case of spontaneous fungal peritonitis in a patient with cirrhosis. A 70-year-old woman with cirrhosis secondary to autoimmune hepatitis was admitted with fever and abdominal distention. Paracentesis revealed neutrocytosis, and despite appropriate antibacterial coverage, no clinical improvement was noted and the ascitic fluid white cell count increased on repeat paracentesis. Two consecutive ascitic fluid cultures grew Candida glabrata, and antifungal therapy with amphotericin was initiated, pending sensitivity of the isolate. Because of worsening renal function, amphotericin was discontinued and itraconazole was started, as sensitivity of the isolate was then available. Antifungal therapy resulted in resolution of ascitic fluid neutrocytosis and culture negativity. However, the patient's renal function continued to deteriorate, necessitating hemodialysis. Despite multiple courses of antibiotics, she died of fulminant sepsis and multiorgan failure.

Clostridium difficile and vancomycin-resistant enterococcus: the new nosocomial alliance.

OBJECTIVES: The aims of this study were to determine the frequency of the association between Clostridium difficile (C. difficile) and vancomycin-resistant Enterococcus (VRE) and delineate the role of C. difficile coinfection as a predictor of VRE infection versus colonization and adverse outcome. METHODS: Patients with both C. difficile colitis and VRE (CD/VRE) were compared to patients with VRE alone with regard to demographics, comorbidity, prior antibiotic therapy, and coinfection with methicillin-resistant Staphylococcus aureus and funguria. C. difficile as a predictor of VRE infection (VRE-I) versus colonization (VRE-C) and adverse outcome was also studied. RESULTS: Eighty-nine patients with VRE infection or colonization were studied. This included 31 cases of VRE-I and 58 VRE-C. C. difficile was isolated in 17 (19.1%) of patients; of these C. difficile was isolated before VRE in 9 patients and after VRE in 8. The two groups did not differ in age, residence, or comorbidity. C. difficile coinfection was not predictive of VRE-I versus VRE-C, nor was it associated with increased length of stay or mortality. However, the mortality rates in both groups was high, around 30%. A significant association was noted between the use of vancomycin and metronidazole (before the isolation of VRE) and C. difficile coinfection (p = 0.03 and p = 0.001, respectively). A high incidence of nosocomial coinfection with methicillin-resistant Staphylococcus aureus, funguria, and gram-negative sepsis was noted in both groups; the association with funguria was statistically significant (p = 0.029). CONCLUSIONS: In conclusion, C. difficile coinfection is common in patients with VRE infection or colonization and is significantly associated with other nosocomial dilemmas like funguria. This may result in the emergence of highly virulent pathogens including vancomycin-resistant C. difficile, posing new challenges in the management of nosocomial diarrheas.

Clostridium difficile colitis: factors influencing treatment failure and relapse--a prospective evaluation.

OBJECTIVE: The aim of this study was to identify patient related factors that may influence the treatment response and relapse following Clostridium difficile (C. difficile) colitis. METHODS: A total of 36 patients with C. difficile colitis were followed for 3 months. Age, sex, place of residence, severity of infection, treatment, underlying medical condition, and treatment were compared in patients who failed to respond to treatment in 14 days and in patients who relapsed after a successful treatment. Student's t test and Fisher's exact test were used to compare the groups. A p value of <0.05 was considered significant. RESULTS: A low serum albumin (p=0.016) and continuation of systemic antibiotic treatment were found to be associated with refractoriness to treatment. Continuation or restarting of antibiotics after successful treatment increases the risk of relapse (p=0.003). The age, sex place of residence, underlying medical condition, and type of precipitating antibiotics had no effect on the treatment response and relapse. The severity of colitis and the type of therapy (metronidazole vs vancomycin) did not influence the treatment response or relapse. CONCLUSION: Low serum albumin serves as a useful marker for patients who require prolonged treatment for C. difficile colitis. It is prudent to review the need for the continuation of systemic antibiotic treatment, as it adversely affects the treatment response and increases the risk of relapse.

Activated microglia are the principal glial source of thromboxane in the central nervous system.

Thromboxane A2(TxA2) is a potent vasoconstrictor associated with cerebrovascular disease and is thought to be synthesized within tissues of the brain. In order to determine the cellular sources of TxA2 in the central nervous system (CNS), we measured the release of the stable metabolite TxB2 in cultures of mixed or highly enriched populations of brain glia. Using techniques which isolated large numbers of highly enriched microglia and astroglia, we found that only microglia release TxB2. Moreover, microglia, not astroglia, contain the requisite synthetic enzyme thromboxane synthase. Phagocytic signals and lipopolysaccharide are potent stimulants of microglial release of thromboxane, with lesser effects shown by platelet activating factor and substance P. We conclude that microglia, when activated, are the principal source of brain-derived thromboxane and may help to control vascular flow at sites of acute CNS injury.

Prognostic criteria in Clostridium difficile colitis.

OBJECTIVE: To determine the prognostic factors in Clostridium difficile (CD) colitis. METHODS: We conducted a retrospective study of proven cases of CD colitis in l8 months. Seventy six patients (from a 605-bed community hospital in the Bronx, NY) with proven CD colitis were studied. Mortality in patients with CD colitis was also examined. RESULTS: Seventy six patients with proven CD colitis were admitted between January 1993 and June 1994. Eighteen patients died during the same admission. Upon admission, serum albumin was less than 25 g/L in 12 (20.6%) of the survivors and in eight (44%) of the deceased patients (p <0.05). A fall in serum albumin levels was noted with the onset of symptoms of CD colitis in those who survived as well as in those who died, with a greater fall of 11.2 g/L (range 10-20 g/L) in patients who died compared with a fall of 6 g/L (range 5-10 g/L)in those who survived (p <0.05). Use of more than three antibiotics was noted in 13 (72%) of those who died and in 18 (31%) of those who survived (p <0.05). Persistence of CD cytotoxin 7 or more days after initiation of treatment was present in 14 (77%) of those who died and in eight (13%) of the survivors (p <0.01). Duration of hospitalization correlated with the development of CD colitis (35.89 vs 11.7 days) with no significant difference between survivors and deceased patients with CD colitis. Factors such as age, sex, residence, past medical history score, mean score of presenting complaints of CD colitis, history of prior episodes CD colitis, and mean number of recurrent episodes showed no difference in mortality. CONCLUSION: Factors predictive of an increased mortality in patients with CD colitis include a serum albumin of less than 25 g/L on admission, a fall in serum albumin level of greater than 11 g/L at the onset of symptoms of CD colitis, use of three or more antibiotics, and persistence of positive CD cytotoxin in the stool after completion of 7 or more days of treatment.

Models for determining cost of care and length of stay in neonatal intensive care units.

New models for determining the cost of care and length of stay in the neonatal intensive care unit (NICU) were developed using financial and clinical data from 588 admissions to our NICU. The model for determining costs explained 71% of the variability in total hospital costs. Models such as the ones developed in this study can be used to compare costs in different institutions, determine temporal trends in costs, and examine the financial impact of using new technologies. Such models can also be useful components of a rational prospective pricing system for the NICU.

Tuberculosis surveillance of community hospital employees. A recommended strategy.

OBJECTIVE AND METHODS: To suggest a cost-effective strategy with a high degree of surveillance for the transmission of tuberculosis infection to employees in community hospitals. We performed a cost-benefit analysis of tuberculin skin testing over a 4-year period. The setting was a community hospital in Bronx, NY. The subjects consisted of employees of the hospital who were categorized into high-risk employees defined as individuals who worked daily in patient care and low-risk employees defined as those not directly involved in patient care. All cases of tuberculin skin test conversion among employees were reviewed over a 4-year period. The departments involved, total number of employees, chest radiographic findings, and prophylaxis instituted were noted. RESULTS: The number of employees who were screened over the past 4 years consisted of 897 in 1990, 857 in 1991, 1357 in 1992, and 1316 in 1993. The mean annual conversion rate was 1%, 1.5%, 1.7%, and 1.4% for the 4 years, respectively. Skin test conversions according to job description revealed that of the total number of conversions 42% were from the nursing staff, 6.2% among the physicians and residents, and 52% among the ancillary staff. There was no difference in conversion between medical and nonmedical services such as the gynecology and surgical floors. CONCLUSION: Since tuberculin conversion rates of high-risk employees and those exposed to infectious tuberculosis cases have been low, we suggested a comprehensive strategy of 6-month tuberculin testing for high-risk employees and yearly testing for low-risk employees and eliminating boosting and repeated testing at 12 weeks in those exposed to infectious cases of tuberculosis.

Reactive mononuclear phagocytes release neurotoxins after ischemic and traumatic injury to the central nervous system.

Reactive microglia and invading macrophages, which appear in brain damaged by stroke or trauma, secrete neuron-killing factors. This release of cytotoxic substances is a delayed process and is not detected until inflammatory cells reach a peak of reactivity by the second day after injury. Proximity to the site of injury and density of mononuclear phagocytes determine in part the amount of neurotoxic activity released by injured tissues. Moreover, drugs that suppress the accumulation of reactive microglia and macrophages also reduce tissue production of neuron poisons. Neurotoxins released by brain inflammatory cells or extracted directly from inflamed tissues are heat-stable, protease-resistant molecules < 500 daltons with actions blocked by N-methyl-D-aspartate (NMDA) receptor antagonists. These molecules are distinguished from free radical intermediates, bind to cation exchange resins, lack carboxyl moieties, and are separated from excitatory amino acids including glutamate or aspartate and from the NMDA receptor-mediated toxin quinolinic acid by ion exchange and reverse phase chromatography. Our data suggest that an unrecognized class of neuron-killing molecules produced by inflammatory cells mediate the delayed neuronal loss associated with stroke and trauma.

Brain glia release factors with opposing actions upon neuronal survival.

Microglia and astroglia have been thought to govern the survival of neurons after damage to the CNS. To investigate these putative glia-neuron relationships, we examined microglia and astroglia secretion products for effects upon growth of cultured neurons. Activated microglia secrete small neurotoxic factors (< 500 Da), while astroglia constitutively release proteins (> 10 kDa) that promote neuronal growth. Proteins released from astroglia, moreover, attenuate microglial toxicity, suggesting that different glial populations have opposing actions upon neuronal survival. Further study shows that neurotoxins from microglia are heat-stable, protease-resistant molecules with biologic activities blocked by NMDA receptor antagonists. Microglial factors, although toxic for chick ciliary neurons and rat spinal cord neurons, did not reduce numbers of oligodendroglia, astroglia, or Schwann cells in culture. The microglial neurotoxins can be distinguished from cytokines, from free radical intermediates, from the excitatory amino acids glutamate or aspartate, and from the NMDA receptor-mediated toxin quinolinic acid. We propose that secretion products from reactive microglia, but not astroglia, endanger surviving neurons after CNS injury by release of a novel class of neuron-killing molecules.

Problems in the use of serologic tests for the diagnosis of Lyme disease.

Lyme disease can be reliably diagnosed in the presence of erythema migrans. When erythema migrans is absent, serologic tests are often used to confirm the diagnosis. To choose a test for our Lyme disease diagnostic center, serum samples were obtained from 34 patients and tested for antibodies to Borrelia burgdorferi. We evaluated five enzyme-linked immunosorbent assays from Stony Brook (NY) University Hospital, Cambridge Bioscience (Worcester, Mass), Hillcrest Biologicals (Cypress, Calif), Sigma Diagnostics (St Louis, Mo), and Zeus-Wampole Scientific Inc (Raritan, NJ) and two fluorescent antibody tests (3M [Diagnostic Systems Inc, Santa Clara, Calif] and FIAX [Whittaker M.A. Bioproducts Inc, Walkersville, Md]). A positive sample by any test was further analyzed by Western blot. Using the Centers for Disease Control (Atlanta, Ga) epidemiologic case definitions, patients were classified into those with clinical Lyme disease, patients not meeting the Centers for Disease Control definitions, and asymptomatic patients. Sensitivities of Lyme serologies varied from 13% to 73%, with Hillcrest showing the highest value and Sigma the lowest value. False-positive test results were found in 0% to 27% of patients. Western blot analysis was positive in six of 15 patients with clinical Lyme disease. These results emphasize the need for better serologic testing for Lyme disease and underline their usefulness only as adjuncts in the clinical diagnosis of Lyme disease.

Teenage pregnancy: trend and impact on rates of low birth weight and fetal, maternal, and neonatal mortality in the United States.

The trend of teenage pregnancy and its impact on national rates of low birth weight and fetal, neonatal, and maternal mortality in the United States was examined. It is our conclusion that the unfavorable outcomes associated with teenage pregnancy may be related more closely to other sociodemographic variables associated with pregnant teenagers than to biologic age itself.

Maternal age and incidence of low birth weight at term: a population study.

A total of 184,567 singleton live births with gestational ages of 40 weeks were examined from the 1980-1984 Illinois birth certificate data to determine the independent effect of maternal age on the incidence of low birth weight at term. The incidence is highest in mothers less than 17 years of age (3.2%) and gradually declines with advancing maternal age to reach 1.3% in women aged 25 to 34 years. It increases to 1.7% for those greater than 35 years of age. To separate out the independent effect of maternal age on the incidence of low birth weight infants at term, the presence of other maternal factors, such as race, education, parity, marital status, and prenatal care, were adjusted by use of a series of multiple logistic regression analyses. All of these analyses consistently demonstrated that the adjusted risk for low birth weight at term is the lowest in teenagers and increases with advancing maternal age. These results indicate that the high incidence of this factor in young mothers apparently reflects their poor sociodemographic and prenatal care status. Advancing maternal age is associated with a decreased potential for fetal growth, possibly reflecting biologic aging of maternal tissues and systems or the cumulative effects of disease.