Results of a pilot trial comparing prolonged intravenous antibiotics with sequential intravenous/oral antibiotics for children with perforated appendicitis

HYPOTHESIS

For children with perforated appendicitis, the use of a prolonged course of intravenous (i.v.) antibiotics is equivalent to a short course of i.v. antibiotics followed by sequential conversion to oral (PO) antibiotics.

DESIGN

Prospective, randomized, clinical trial.

SETTING

Multicenter study in tertiary children's hospitals.

PATIENTS

Children (aged 5-18 years) with perforated appendicitis found at laparotomy.

INTERVENTION

Children were randomized after appendectomy either to a 10-day course of a combination of i.v. ampicillin, gentamicin sulfate, and clindamycin (n = 10); or to a short course of a combination of i.v. ampicillin, gentamicin, and clindamycin, followed by conversion to a combination of p.o. amoxicillin and clavulanate potassium plus metronidazole (n = 16).

MAIN OUTCOME MEASURES

The primary outcome measure was clinical success, which was rated as complete, partial, or failure. Secondary outcome measures included return of oral intake, duration of fever, return of normal white blood cell count, and patient charges. Treatment equivalence was determined using confidence interval analysis.

RESULTS

We found treatment equivalence between the i.v. and i.v./p.o. groups, with 6 (60%) complete and 4 (40%) partial successes for the 10 patients in the i.v. group and 15 (94%) complete and 1 (6%) partial successes for the 16 patients in the i.v./p.o. group (P< or =.05). There was no difference in return of oral intake, duration of fever, or return of normal white blood cell count between the groups. Conversion to oral therapy results in savings of approximately $1500 per case.

CONCLUSION

There is treatment equivalence between prolonged i.v. therapy and i.v. therapy followed by conversion to oral antibiotic therapy in children with perforated appendicitis.

Growth inhibition of a Fusarium verticillioides GUS strain in corn kernels of aflatoxin-resistant genotypes

Two corn genotypes, GT-MAS:gk and MI82, resistant to Aspergillus flavus infection/aflatoxin contamination, were tested for their ability to limit growth of Fusarium verticillioides. An F. verticillioides strain was transformed with a beta-glucuronidase (GUS) reporter gene (uidA) construct to facilitate fungal growth quantification and then inoculated onto endosperm-wounded and non-wounded kernels of the above-corn lines. To serve as a control, an A. flavus strain containing the same reporter gene construct was inoculated onto non-wounded kernels of GT-MAS:gk. Results showed that, as in a previous study, non-wounded GT-MAS:gk kernels supported less growth (six- to ten-fold) of A. flavus than did kernels of a susceptible control. Also, non-wounded kernels of GT-MAS:gk and M182 supported less growth (two- to four-fold) of F. verticillioides than did susceptible kernels. Wounding, however, increased F. verticillioides infection of MI82, but not that of GT-MAS:gk. This is in contrast to a previous study of A. flavus, where wounding increased infection of GT-MAS:gk rather than M182 kernels. Further study is needed to explain genotypic variation in the kernel response to A. flavus and F. verticillioides kernel infections. Also, the potential for aflatoxin-resistant corn lines to likewise inhibit growth of F. verticillioides needs to be confirmed in the field.

Comparison of constitutive and inducible maize kernel proteins of genotypes resistant or susceptible to aflatoxin production

Maize genotypes resistant or susceptible to aflatoxin production or contamination were compared for differences in both constitutive and inducible proteins. Five additional constitutive proteins were found to be associated with resistance in over 8 of the 10 genotypes examined. Among these, the 58- and 46-kDa proteins were identified as globulin-1 and globulin-2, respectively. Differences in the ability to induce specific antifungal proteins, such as the higher synthesis of the 22-kDa zeamatin in resistant genotypes, were also observed between resistant and susceptible kernels incubated under germinating conditions (31 degrees C, 100% humidity). Both constitutive and inducible proteins appear to be necessary for kernel resistance. Embryo-killed kernels (unable to synthesize new proteins) supported the highest level of aflatoxins, whereas imbibed kernels (to hasten protein induction) supported the lowest among all treatments. This suggests that the synthesis of new proteins by the embryo plays an important role in conferring resistance. However, significantly lower levels of aflatoxin production in embryo-killed resistant kernels than in susceptible ones suggest that, in reality, high levels of constitutive antifungal proteins are indispensable to kernel resistance.

Identification of chemical components of corn kernel pericarp wax associated with resistance to Aspergillus flavus infection and aflatoxin production

Kernel pericarp wax of the corn breeding population GT-MAS:gk has been associated with resistance to Aspergillus flavus infection and aflatoxin production. GT-MAS:gk wax, previously compared to waxes of three susceptible genotypes, was presently compared to wax of a different, and more numerous, group of susceptible lines. Wax separation by TLC confirmed previous findings, demonstrating a unique GT-MAS:gk band and a unique "susceptible" band. Only GT-MAS:gk wax inhibited the growth of A. flavus; however, no association was established, as before, between kernel wax abundance and resistance. Gas chromatography-mass spectroscopy (GC-MS) analysis of kernel whole wax showed a higher percentage of phenol-like compounds in wax from GT-MAS:gk than in waxes from the susceptible lines. The GT-MAS:gk unique band contained phenol-like compounds and ethyl-hexadecanoate; butyl-hexadecanoate was preeminent in most of the "susceptible bands". Alkylresorcinol (phenolic compounds) content was dramatically higher in GT-MAS:gk wax than in the wax of susceptible lines. An alkylresorcinol, 5-methylresorcinol, also inhibited in vitro growth of A. flavus. These and other phenolic compounds may contribute to kernel wax inhibition of A. flavus infection/aflatoxin production. Further investigation is needed to confirm a role for them in GT-MAS:gk resistance.

Cervical spine injuries in children: a review of 103 patients treated consecutively at a level 1 pediatric trauma center

PURPOSE

Cervical spine (C-spine) injuries occur infrequently in children but may be associated with significant disability and mortality. The purpose of this study was to review the experience of a level 1 pediatric trauma center to determine the epidemiology, risk factors, mechanisms, levels, types of injury, comorbid factors, and outcomes associated with these potentially devastating injuries.

METHODS

A retrospective analysis of 103 consecutive C-spine injuries treated at a level 1 pediatric trauma center over a 9(1/2)-year period (January 1991 through August 2000) was performed.

RESULTS

The mean age was 10.3 +/- 5.2 years, and the male-to-female ratio was 1.6:1. The most common mechanism of injury was motor vehicle related (52%), followed by sporting injuries (27%). Football injuries accounted for 29% of all sports-related injuries. Sixty-eight percent of all children sustained injuries to C1 to C4; 25% to C5 to C7; and 7% to both. Spinal cord injury without radiographic abnormality (SCIWORA) occurred in 38%. Five patients had complete cord lesions involving the lower C-spine (C4 to C7); 4 of these were motor vehicle related, and all 4 patients died. Isolated C-spine injuries occurred in 43%, whereas 38% had associated closed head injuries (CHI). The overall mortality rate was 18.5%, most commonly motor vehicle related (95%), occurring in younger children (mean and median age 5 years) and associated with upper C-spine injuries (74%) and CHI (89%). C1 dislocations occurred in younger children (mean age, 6.6 years), most often as a result of motor vehicle-related trauma (especially pedestrians) and were associated with the highest injury severity score (ISS), longest length of stay (LOS), most CHIs, and the highest mortality rate (50%). C-spine fractures with or without SCI occurred most commonly as a result of falls and dives. Sporting injuries occurred almost exclusively in adolescent boys (mean age, 13.8 years) and were isolated injuries associated with a relatively low ISS and shorter LOS. Interestingly, 75% of sporting injuries showed SCIWORA, and all infants suffering from child abuse had SCIWORA.

CONCLUSIONS

Mechanisms of injury are age related, with younger children sustaining C-spine injuries as a result of motor vehicle-related trauma and older adolescents commonly injured during sporting activities. C-spine injuries in children most commonly involve the upper C-spine, but complete lesions of the cord are associated more frequently with lower C-spine injuries. The type of C-spine injury is related to the mechanism of injury: SCIWORA is associated with sporting activities and child abuse, C-spine dislocations most commonly result from motor vehicle-related trauma (especially among pedestrians), and C-spine fractures occur most commonly as a result of falls and dives. Predictors of mortality include younger age, motor vehicle-related mechanism, C1 dislocations, high ISS greater than 25, and associated CHI. A high index of suspicion for SCIWORA is essential when evaluating adolescents with neck trauma associated with sporting injuries or victims of child abuse.

A two-item conjoint screen for alcohol and other drug problems

BACKGROUND

Although nonmedical use of illicit and prescription drugs is not uncommon among American adults, the currently recommended screens for substance use disorders focus only on alcohol. This study reports on the criterion validity of a two-item conjoint screen (TICS) for alcohol and other drug abuse or dependence for a split sample of primary care patients.

METHODS

Two random samples of primary care patients aged 18 to 59 years responded to several screening items that emanated from a focus group process. The DSM-III-R criteria for substance use disorders, as codified by the Composite International Diagnostic Interview-Substance Abuse Module, served as the criterion standard.

RESULTS

At least one positive response to the TICS (In the last year, have you ever drunk or used drugs more than you meant to? and Have you felt you wanted or needed to cut down on your drinking or drug use in the last year?) detected current substance use disorders with nearly 80% sensitivity and specificity. The TICS was particularly sensitive to polysubstance use disorders. Respondents who gave 0, 1, and 2 positive responses had a 7.3%, 36.5%, and 72.4% chance of a current substance use disorder, respectively; likelihood ratios were 0.27, 1.93, and 8.77. The results were consistent across split samples of 434 and 702 participants.

CONCLUSIONS

Current alcohol or other drug problems can be detected in nearly 80% of young and middle-aged patients by asking two questions that are easily integrated into a clinical interview.

Variation in in vitro alpha-amylase and protease activity is related to the virulence of Aspergillus flavus isolates

Variation in the ability of Aspergillus flavus isolates to spread between cotton boll locules was previously shown to be at least partially related to variation in the production of a specific polygalacturonase (pectinase P2C). To determine if non-pectolytic hydrolase differences between low- and high-virulence isolates exist and, thus, could also potentially contribute to virulence differences, the present investigation was undertaken. Two A. flavus isolates, AF12 with low virulence and lacking pectinase P2C and AF13 with high virulence and producing pectinase P2C, were compared for production of nonpectolytic hydrolases after growth in 10% potato dextrose broth. Activity of amylases, cellulases, xylanases, and proteases was quantified using the radial diffusion/cup plate technique followed by differential staining. Culture filtrates also were subjected to native polyacrylamide gel electrophoresis. Both isolates produced amylases, proteases, and xylanases, whereas cellulases were not detected for either. AF13 produced more amylase than AF12, and this difference was supported by amylase isoform differences between isolates on native polyacrylamide gel electrophoresis gels. AF13 also produced more protease than AF12; however, isoform differences between isolates were inconclusive. These variations in other hydrolytic activities (besides pectinases) may contribute to virulence differences in cotton bolls between AF12 and AF13.

Resistance to aflatoxin accumulation in kernels of maize inbreds selected for ear rot resistance in West and Central Africa

Thirty-six inbred lines selected in West and Central Africa for moderate to high resistance to maize ear rot under conditions of severe natural infection were screened for resistance to aflatoxin contamination using the previously established kernel screening assay. Results showed that more than half the inbreds accumulated aflatoxins at levels as low as or lower than the resistant U.S. lines GT-MAS:gk or MI82. In 10 selected aflatoxin-resistant or aflatoxin-susceptible inbreds, Aspergillus flavus growth, which was quantified using an A. flavus transformant containing a GUS-beta-tubulin reporter gene construct, was, in general, positively related to aflatoxin accumulation. However, one aflatoxin-resistant inbred supported a relatively high level of fungal infection, whereas two susceptibles supported relatively low fungal infection. When kernels of the 10 tested lines were profiled for proteins using sodium dodecyl sulfate-polyacrylamide gel electrophoresis, significant variations from protein profiles of U.S. lines were observed. Confirmation of resistance in promising African lines in field trials may significantly broaden the resistant germplasm base available for managing aflatoxin contamination through breeding approaches. Biochemical resistance markers different from those being identified and characterized in U.S. genotypes, such as ones inhibitory to aflatoxin biosynthesis rather than to fungal infection, may also be identified in African lines. These discoveries could significantly enhance the host resistance strategy of pyramiding different traits into agronomically useful maize germplasm to control aflatoxin contamination.

Elliptic flow in Au+Au collisions at square root(S)NN = 130 GeV

Elliptic flow from nuclear collisions is a hadronic observable sensitive to the early stages of system evolution. We report first results on elliptic flow of charged particles at midrapidity in Au+Au collisions at square root(S)NN = 130 GeV using the STAR Time Projection Chamber at the Relativistic Heavy Ion Collider. The elliptic flow signal, v2, averaged over transverse momentum, reaches values of about 6% for relatively peripheral collisions and decreases for the more central collisions. This can be interpreted as the observation of a higher degree of thermalization than at lower collision energies. Pseudorapidity and transverse momentum dependence of elliptic flow are also presented.

Analysis of acoustic communication by ants

An analysis is presented of acoustic communication by ants, based on near-field theory and on data obtained from the black imported fire ant Solenopsis richteri and other sources. Generally ant stridulatory sounds are barely audible, but they occur continuously in ant colonies. Because ants appear unresponsive to airborne sound, myrmecologists have concluded that stridulatory signals are transmitted through the substrate. However, transmission through the substrate is unlikely, for reasons given in the paper. Apparently ants communicate mainly through the air, and the acoustic receptors are hairlike sensilla on the antennae that respond to particle sound velocity. This may seem inconsistent with the fact that ants are unresponsive to airborne sound (on a scale of meters), but the inconsistency can be resolved if acoustic communication occurs within the near field, on a scale of about 100 mm. In the near field, the particle sound velocity is significantly enhanced and has a steep gradient. These features can be used to exclude extraneous sound, and to determine the direction and distance of a near-field source. Additionally, we observed that the tracheal air sacs of S. richteri can expand within the gaster, possibly amplifying the radiation of stridulatory sound.

Evaluation of serum-free culture conditions able to support the ex vivo expansion and engraftment of human hematopoietic stem cells in the human-to-sheep xenograft model

To develop culture conditions devoid of serum that would support the ex vivo expansion and maintenance of hematopoietic stem cells (HSC) with engraftment capability, we performed in vitro studies in which phenotypic and functional expansion of putative HSC populations were evaluated. We then used the human-sheep xenograft model to evaluate the engraftment potential of the ex vivo expanded cells. Adult human bone marrow CD34+-enriched cells were cultured in QBSF-60 for 14 days with or without fetal bovine serum (FBS) in the presence of interleukin-3 (IL-3), IL-6, and stem cell factor (SCF), and analyzed at days 0, 3, 7, and 14 for expansion, phenotype, clonogenic ability, and cell cycling status. Although there was a progressive expansion of numbers of cells in both groups, the group cultured with serum exhibited more than twice the expansion seen in the group without serum at all time points. The phenotypic analysis of the cultured cells showed an increase in the absolute numbers of CD34+ cells in both groups. However, when we evaluated the presence of CD34+CD38- cells, this population persisted in significantly higher numbers in the group cultured without serum, with maximal output of CD34+CD38- cells seen at 3 and 7 days. A higher total clonogenic potential was found in the serum-free cultures. To evaluate the in vivo engraftment potential of these cultured cells, 19 sheep fetuses were each injected i.p. with 9 x 10(5) cells either fresh or cultured in the conditions described above. Although all the transplanted fetal sheep showed the presence of human cells in their bone marrow (BM), the highest levels of long-term engraftment in primary recipients were obtained with the fraction of cells cultured for 3 days followed by 7 days in the absence of serum. In the secondary sheep recipients, the highest level of long-term engraftment was also achieved in sheep that received cells from primary recipients that had received cultured cells in serum-free conditions for 3 days.

A novel ryanodine receptor mutation and genotype-phenotype correlation in a large malignant hyperthermia New Zealand Maori pedigree

Malignant hyperthermia (MH) is a pharmacogenetic disorder that predisposes to a sometimes fatal hypermetabolic reaction to halogenated anaesthetics. MH is considered to originate from abnormal regulation of skeletal muscle Ca(2+) release. Current diagnosis of MH susceptibility (MHS) relies on in vitro contracture testing (IVCT) of skeletal muscle. The ryanodine receptor (RYR1) encoding the major Ca(2+) release channel in the skeletal muscle sarcoplasmic reticulum has been shown to be mutated in a number of MH pedigrees. The large Maori pedigree reported here is the largest MHS pedigree investigated to date and comprises five probands who experienced clinical episodes of MH and 130 members diagnosed by the IVCT. Sequencing of the 15 117 bp RYR1 cDNA in a MHS individual from this pedigree identified a novel C14477T transition that results in a Thr4826 to Ile substitution in the C-terminal region/transmembrane loop of the skeletal muscle ryanodine receptor. This is the first mutation in the RyR1 C-terminal region associated solely with MHS. Although linkage analysis showed strong linkage (max LOD, 11.103 at theta = 0.133) between the mutation and MHS in the pedigree using the standardized European IVCT phenotyping protocol, 22 MHS recombinants were observed. The relationship between the IVCT response and genotype was explored and showed that as IVCT diagnostic cut-off points were made increasingly stringent, the number of MHS discordants decreased with complete concordance between the presence or absence of the C14477T mutation and MHS and MH normal phenotypes, respectively, using a cut-off of 1.2 g tension at 2.0 mM caffeine and 1.8 g tension at 2.0% halothane. Many MHS pedigrees investigated have been excluded from linkage to the RYR1 gene on the basis of a small number of recombinants; however, the linkage analysis reported here suggests that other recombinant families excluded from linkage to the RYR1 gene may actually demonstrate linkage as the number of members tested within the pedigrees increases. The high number of discordants observed using the standardized diagnostic cut-off points is likely to reflect the presence of a second MHS susceptibility locus in the pedigree.

Remission of alcohol disorders in primary care patients. Does diagnosis matter?

BACKGROUND

Alcohol use disorders (AUDs) are prevalent in primary care patient populations. Many primary care patients with AUDs can remit without formal treatment. An understanding of the factors that predispose patients to remission may help primary care physicians provide effective brief counseling for those with mild to moderate disorders and more effectively recommend formal treatment for others.

METHODS

A total of 119 eligible and randomly selected primary care patients with alcohol abuse or dependence in remission (as defined in Diagnostic and Statistical Manual of Mental Disorders, third edition, revised) participated in a semistructured telephone interview.

RESULTS

Of the subjects, 59.7% were women; 50.4% had been alcohol dependent; 66.3% made a conscious decision to modify their drinking; and 62.1%, including 54.2% of the alcohol-dependent subjects, moderated their drinking without abstaining. Family, emotional, and medical issues most often prompted reduced drinking. Nearly one third of the subjects found specific strategies and rules helpful in reducing their drinking, and many cited circumstances that helped or hindered their efforts. Only 10.9% had formal alcohol treatment.

CONCLUSIONS

A significant proportion of patients with AUDs remitted without formal treatment. Abstinence may not be necessary for a subset of dependent patients. When counseling patients with active AUDs, primary care clinicians are advised to counsel patients about the psychosocial and medical reasons to control drinking, promote rule-setting about drinking, help patients avoid circumstances that trigger drinking, and support patients' attempts at moderating drinking rather than abstaining. Motivational interviewing (motivational enhancement therapy) may provide a useful framework for such counseling.

Malignant hyperthermia in infancy and identification of novel RYR1 mutation

Malignant hyperthermia (MH) has been reported as non-existent in children less than 1 yr old, although several unconfirmed reports have been published. A case report of MH in a 6-month-old child is presented, with confirmation of MH susceptibility by in vitro contracture testing of quadriceps muscle at 13 yr old. Genetic analysis revealed a novel RYR1 mutation that substitutes arginine 2452 for tryptophan in a region of the calcium channel mutated in several other MH pedigrees.

Improving prevention systems in primary care practices: the Health Education and Research Trial (HEART)

BACKGROUND

The Health Education and Research Trial (HEART) was a multicenter clinical trial designed to test methods to improve primary care practice systems for heart disease prevention services. We present the trial methodology, the practices' use of medical record tools, and changes in documentation of cardiovascular risk factor screening and management.

METHODS

Primary care practices were recruited from 4 Midwestern states. The factorial design resulted in 4 study groups: conference only, conference and quality improvement consultations, conference and prevention coordinator, and all interventions combined. Medical record audits and physician, staff, and patient surveys assessed practice change in cardiovascular disease risk factor documentation.

RESULTS

Practices participated fully in this project, set goals to improve preventive services, and implemented recommended medical record tools. The number of goals set and the increase in the use of medical record tools were greatest in the combined intervention group, with improvements noted in all groups. The use of patient history questionnaires, problem lists, and flow sheets was significantly higher in the combined intervention group when compared with the conference-only group. Documentation of risk factor screening in a recommended-medical record location improved in all intervention groups, with significant sustained improvements in the practices that received the combined intervention. Documented risk factor management significantly improved in all intervention groups compared with the conference-only control.

CONCLUSION

Primary care practices are interested in improving prevention systems and can change these systems in response to supportive external interventions. Promoting organizational change to produce sustained improvement in preventive service clinical outcomes is a complex process that requires further research.

Otitis media, fluctuant hearing loss, and speech-language outcomes: a preliminary structural equation model

The goals of this study were to estimate the risk for lowered speech-language outcomes associated with early recurrent otitis media with effusion (OME) with and without hearing loss and to develop a preliminary descriptive-explanatory model for the findings. Three statistical approaches were used to assess associations among OME, hearing loss, and speech-language outcomes. Participants were a subsample of 70 children followed prospectively in the Dallas Cooperative Project on Early Hearing and Language Development (Friel-Patti & Finitzo, 1990). Findings indicated that hearing levels at 12-18 months were significantly associated with speech delay and low language outcomes at 3 years of age. The risk for subclinical or clinical speech delay at 3 years of age was 2% for children with less than 20 dB average hearing levels at 12-18 months and 33% for children with greater than 20 dB average hearing levels at 12-18 months. A structural equation model (Jöreskog & Sörbom, 1993) indicated that the significant and substantial effects of hearing levels at 12-18 months on speech status at 3 years were significantly mediated by language status at 3 years. Discussion includes implications of these findings for alternative speech perception models linking early OME and hearing loss to later speech-language disorder.

Irreversible activation of cyclic nucleotide-gated ion channels by sulfhydryl-reactive derivatives of cyclic GMP

First discovered in the sensory epithelium of the visual and olfactory systems, cyclic nucleotide-gated (CNG) ion channels have now been found in tissues throughout the body. Native rod CNG channels are tetramers composed of homologous, but distinct, alpha- and beta-subunits. The goal of this study was to develop a novel method for targeting covalent attachment of cGMP to individual subunit types. Toward this goal, we have found that treatment of membrane patches expressing rod alpha-subunit channels with sulfhydryl-reactive derivatives of cGMP resulted in irreversible activation. The persistent currents were sensitive to block by both Mg(2+) and tetracaine. Pretreatment of the patch with the sulfhydryl-blocking reagents N-ethylmaleimide (NEM) and bis-dithionitrobenzoic acid (DTNB) prevented covalent activation; the effect of DTNB was reversed by reduction with DTT. Furthermore, the process of covalent activation was dramatically slowed by the presence of an excess of 8-Br-cGMP. These results suggested that covalent activation resulted from the tethering of cGMP near the channel's ligand-binding sites by reaction with an endogenous cysteine. The alpha-subunit of the rod channel contains seven cysteine residues, and we set out to determine the site of attachment by site-directed mutagenesis. Surprisingly, irreversible activation was not abolished by elimination of all seven cysteine residues. This result suggests that the site of attachment is on a tightly associated protein, rather than on the channel protein itself. To further investigate these results, we treated patches containing irreversibly activated channels with 100 microg/mL trypsin and discovered two modes of covalent activation. One type developed rapidly and was removed by trypsin treatment, and the second developed slowly and was resistant to trypsin treatment. Both types of covalent activation were present in all mutants tested and were also present when CNG channels were expressed in HEK-293 cells. These results suggest that CNG channel subunits may associate with endogenous proteins when they are expressed in heterologous systems.

Juvenile papillomatosis of the breast in male infants: two case reports

Juvenile papillomatosis of the breast ("Swiss cheese disease") is a benign localized proliferative condition of the breast which occurs almost exclusively in young adult women. Patients with this lesion often have a family history of breast carcinoma, and rarely carcinoma may coexist with the lesion at the time of diagnosis. We present two cases of male infants with juvenile papillomatosis of the breast. The pathology and clinical management of this novel lesion is discussed.

Geomicrobiology of subglacial ice above Lake Vostok, Antarctica

Data from ice 3590 meters below Vostok Station indicate that the ice was accreted from liquid water associated with Lake Vostok. Microbes were observed at concentrations ranging from 2.8 x 10(3) to 3.6 x 10(4) cells per milliliter; no biological incorporation of selected organic substrates or bicarbonate was detected. Bacterial 16S ribosomal DNA genes revealed low diversity in the gene population. The phylotypes were closely related to extant members of the alpha- and beta-Proteobacteria and the Actinomycetes. Extrapolation of the data from accretion ice to Lake Vostok implies that Lake Vostok may support a microbial population, despite more than 10(6) years of isolation from the atmosphere.

Gastrointestinal bleeding in infants and children: Meckel's diverticulum and intestinal duplication

Gastrointestinal bleeding in infants and children can be quite alarming and anxiety-provoking for parents and caregivers alike. In most cases the cause is benign, and the course self-limited. However, in the patient with significant bleeding, an aggressive diagnostic approach is warranted. The differential diagnosis can be extensive and varies depending on the age of the patient. Meckel's diverticula and intestinal duplications may cause gastrointestinal bleeding in almost any age group and require a high index of suspicion for diagnosis. Bleeding usually is painless but may be massive. The advent of technetium (Tc) 99m pertechnetate radionuclide scanning has greatly facilitated the diagnosis of Meckel's diverticula and may also be useful for intestinal duplications. A positive scan requires the presence of ectopic gastric mucosa, which may be identified in both Meckel's diverticula and intestinal duplications. The significance of ectopic gastric mucosa is that it contains acid-secreting parietal cells, which may cause ulceration and bleeding. Only rarely are intestinal duplications diagnosed preoperatively. After initial fluid resuscitation, bleeding from Meckel's diverticula and intestinal duplications require surgical intervention. Resection is the treatment of choice. Diverticulectomy or segmental bowel resection including the diverticulum should be performed for bleeding Meckel's diverticula. It is important to remove the ectopic mucosa and site of ulceration to prevent rebleeding episodes. Intestinal duplications share a common wall and blood supply with native bowel. Segmental resection is indicated if it can be performed without sacrificing a significant portion of bowel. A recent advance has been laparoscopic-assisted resection of Meckel's diverticula and intestinal duplication cysts. With the aid of the laparoscope, extracorporeal or intracorporeal resection may be performed.

A Corn Trypsin Inhibitor with Antifungal Activity Inhibits Aspergillus flavus alpha-Amylase

ABSTRACT In this study, we found that the inhibition of fungal growth in potato dextrose broth (PDB) medium by the 14-kDa corn trypsin inhibitor (TI) protein, previously found to be associated with host resistance to aflatoxin production and active against various fungi, was relieved when exogenous alpha-amylase was added along with TI. No inhibitory effect of TI on fungal growth was observed when Aspergillus flavus was grown on a medium containing either 5% glucose or 1% gelatin as a carbon source. Further investigation found that TI not only inhibited fungal production of extracellular alpha-amylase when A. flavus was grown in PDB medium containing TI at 100 mug ml(-1) but also reduced the enzymatic activity of A. flavus alpha-amylase by 27%. At a higher concentration, however, TI stimulated the production of alpha-amylase. The effect of TI on the production of amyloglucosidase, another enzyme involved in starch metabolism by the fungus, was quite different. It stimulated the production of this enzyme during the first 10 h at all concentrations studied. These studies suggest that the resistance of certain corn genotypes to A. flavus infection may be partially due to the ability of TI to reduce the production of extracellular fungal alpha-amylase and its activity, thereby limiting the availability of simple sugars for fungal growth. However, further investigation of the relationship between TI levels and fungal alpha-amylase expression in vivo is needed.

The single-channel dose-response relation is consistently steep for rod cyclic nucleotide-gated channels: implications for the interpretation of macroscopic dose-response relations

Cyclic nucleotide-gated channels contain four subunits, each with a C-terminal binding site for cGMP or cAMP. The dose-response relation for activation is usually fit with the Hill equation, I/I(max) = [cGMP]n/([cGMP]n + K(1/2)n, where I/I(max) is the fraction of maximal current, K(1/2) is the concentration of cGMP that gives a half-maximal current, and n is the Hill coefficient, taken as the minimum number of ligands required for significant activation. The dose-response relations in multichannel patches are often fit with Hill coefficients of </=2.0, even though other lines of evidence indicate that these channels contain four binding sites and that the binding of three or four ligands is required for significant opening. We have measured dose-response relations for a large number of single cyclic nucleotide-gated channels composed of the bovine rod alpha subunit. We find that the single-channel Hill coefficient is consistently higher than 2.5, with an average of 3.0 +/- 0.37 over 16 patches. In both multichannel and single-channel patches, large variations in K(1/2) have been observed, and are thought to arise from modifications such as phosphorylation. Here we show that mixtures of single channels with high Hill coefficients and variable K(1/2) values will give rise to shallow macroscopic dose-response relations with anomalously low Hill coefficients. This is because activation occurs over a broad range of cGMP concentrations. Thus, dose-response relations from multichannel patches should be interpreted with caution, particularly when detailed mechanistic issues such as cooperativity are being investigated.