SARS-CoV-2 variant of concern fitness and adaptation in primary human airway epithelia

The severe acute respiratory syndrome coronavirus 2 pandemic is characterized by the emergence of novel variants of concern (VOCs) that replace ancestral strains. Here, we dissect the complex selective pressures by evaluating variant fitness and adaptation in human respiratory tissues. We evaluate viral properties and host responses to reconstruct forces behind D614G through Omicron (BA.1) emergence. We observe differential replication in airway epithelia, differences in cellular tropism, and virus-induced cytotoxicity. D614G accumulates the most mutations after infection, supporting zoonosis and adaptation to the human airway. We perform head-to-head competitions and observe the highest fitness for Gamma and Delta. Under these conditions, RNA recombination favors variants encoding the B.1.617.1 lineage 3' end. Based on viral growth kinetics, Alpha, Gamma, and Delta exhibit increased fitness compared to D614G. In contrast, the global success of Omicron likely derives from increased transmission and antigenic variation. Our data provide molecular evidence to support epidemiological observations of VOC emergence.

Viral airway injury promotes cell engraftment in an in vitro model of cystic fibrosis cell therapy

Cell therapy is a potential treatment for cystic fibrosis (CF). However, cell engraftment into the airway epithelium is challenging. Here, we model cell engraftment in vitro using the air-liquid interface (ALI) culture system by injuring well-differentiated CF ALI cultures and delivering non-CF cells at the time of peak injury. Engraftment efficiency was quantified by measuring chimerism by droplet digital PCR and functional ion transport in Ussing chambers. Using this model, we found that human bronchial epithelial cells (HBECs) engraft more efficiently when they are cultured by conditionally reprogrammed cell (CRC) culture methods. Cell engraftment into the airway epithelium requires airway injury, but the extent of injury needed is unknown. We compared three injury models and determined that severe injury with partial epithelial denudation facilitates long-term cell engraftment and functional CFTR recovery up to 20% of wildtype function. The airway epithelium promptly regenerates in response to injury, creating competition for space and posing a barrier to effective engraftment. We examined competition dynamics by time-lapse confocal imaging and found that delivered cells accelerate airway regeneration by incorporating into the epithelium. Irradiating the repairing epithelium granted engrafting cells a competitive advantage by diminishing resident stem cell proliferation. Intentionally, causing severe injury to the lungs of people with CF would be dangerous. However, naturally occurring events like viral infection can induce similar epithelial damage with patches of denuded epithelium. We found that viral preconditioning promoted effective engraftment of cells primed for viral resistance.NEW & NOTEWORTHY Cell therapy is a potential treatment for cystic fibrosis (CF). Here, we model cell engraftment by injuring CF air-liquid interface cultures and delivering non-CF cells. Successful engraftment required severe epithelial injury. Intentionally injuring the lungs to this extent would be dangerous. However, naturally occurring events like viral infection induce similar epithelial damage. We found that viral preconditioning promoted the engraftment of cells primed for viral resistance leading to CFTR functional recovery to 20% of the wildtype.

Host range, transmissibility and antigenicity of a pangolin coronavirus

The pathogenic and cross-species transmission potential of SARS-CoV-2-related coronaviruses (CoVs) remain poorly characterized. Here we recovered a wild-type pangolin (Pg) CoV GD strain including derivatives encoding reporter genes using reverse genetics. In primary human cells, PgCoV replicated efficiently but with reduced fitness and showed less efficient transmission via airborne route compared with SARS-CoV-2 in hamsters. PgCoV was potently inhibited by US Food and Drug Administration approved drugs, and neutralized by COVID-19 patient sera and SARS-CoV-2 therapeutic antibodies in vitro. A pan-Sarbecovirus antibody and SARS-CoV-2 S2P recombinant protein vaccine protected BALB/c mice from PgCoV infection. In K18-hACE2 mice, PgCoV infection caused severe clinical disease, but mice were protected by a SARS-CoV-2 human antibody. Efficient PgCoV replication in primary human cells and hACE2 mice, coupled with a capacity for airborne spread, highlights an emergence potential. However, low competitive fitness, pre-immune humans and the benefit of COVID-19 countermeasures should impede its ability to spread globally in human populations.

A MERS-CoV antibody neutralizes a pre-emerging group 2c bat coronavirus

The repeated emergence of zoonotic human betacoronaviruses (β-CoVs) dictates the need for broad therapeutics and conserved epitope targets for countermeasure design. Middle East respiratory syndrome (MERS)-related coronaviruses (CoVs) remain a pressing concern for global health preparedness. Using metagenomic sequence data and CoV reverse genetics, we recovered a full-length wild-type MERS-like BtCoV/li/GD/2014-422 (BtCoV-422) recombinant virus, as well as two reporter viruses, and evaluated their human emergence potential and susceptibility to currently available countermeasures. Similar to MERS-CoV, BtCoV-422 efficiently used human and other mammalian dipeptidyl peptidase protein 4 (DPP4) proteins as entry receptors and an alternative DPP4-independent infection route in the presence of exogenous proteases. BtCoV-422 also replicated efficiently in primary human airway, lung endothelial, and fibroblast cells, although less efficiently than MERS-CoV. However, BtCoV-422 shows minor signs of infection in 288/330 human DPP4 transgenic mice. Several broad CoV antivirals, including nucleoside analogs and 3C-like/Mpro protease inhibitors, demonstrated potent inhibition against BtCoV-422 in vitro. Serum from mice that received a MERS-CoV mRNA vaccine showed reduced neutralizing activity against BtCoV-422. Although most MERS-CoV-neutralizing monoclonal antibodies (mAbs) had limited activity, one anti-MERS receptor binding domain mAb, JC57-11, neutralized BtCoV-422 potently. A cryo-electron microscopy structure of JC57-11 in complex with BtCoV-422 spike protein revealed the mechanism of cross-neutralization involving occlusion of the DPP4 binding site, highlighting its potential as a broadly neutralizing mAb for group 2c CoVs that use DPP4 as a receptor. These studies provide critical insights into MERS-like CoVs and provide candidates for countermeasure development.

Air-Liquid Interface Cultures to Model Drug Delivery through the Mucociliary Epithelial Barrier

Epithelial cells from mucociliary portions of the airways can be readily grown and expanded in vitro. When grown on a porous membrane at an air-liquid interface (ALI) the cells form a confluent, electrically resistive barrier separating the apical and basolateral compartments. ALI cultures replicate key morphological, molecular and functional features of the in vivo epithelium, including mucus secretion and mucociliary transport. Apical secretions contain secreted gel-forming mucins, shed cell-associated tethered mucins, and hundreds of additional molecules involved in host defense and homeostasis. The respiratory epithelial cell ALI model is a time-proven workhorse that has been employed in various studies elucidating the structure and function of the mucociliary apparatus and disease pathogenesis. It serves as a critical milestone test for small molecule and genetic therapies targeting airway diseases. To fully exploit the potential of this important tool, numerous technical variables must be thoughtfully considered and carefully executed.

A multimodal iPSC platform for cystic fibrosis drug testing

Cystic fibrosis is a monogenic lung disease caused by dysfunction of the cystic fibrosis transmembrane conductance regulator anion channel, resulting in significant morbidity and mortality. The progress in elucidating the role of CFTR using established animal and cell-based models led to the recent discovery of effective modulators for most individuals with CF. However, a subset of individuals with CF do not respond to these modulators and there is an urgent need to develop novel therapeutic strategies. In this study, we generate a panel of airway epithelial cells using induced pluripotent stem cells from individuals with common or rare CFTR variants representative of three distinct classes of CFTR dysfunction. To measure CFTR function we adapt two established in vitro assays for use in induced pluripotent stem cell-derived airway cells. In both a 3-D spheroid assay using forskolin-induced swelling as well as planar cultures composed of polarized mucociliary airway epithelial cells, we detect genotype-specific differences in CFTR baseline function and response to CFTR modulators. These results demonstrate the potential of the human induced pluripotent stem cell platform as a research tool to study CF and in particular accelerate therapeutic development for CF caused by rare variants.

Small molecule eRF3a degraders rescue CFTR nonsense mutations by promoting premature termination codon readthrough

The vast majority of people with cystic fibrosis (CF) are now eligible for CF transmembrane regulator (CFTR) modulator therapy. The remaining individuals with CF harbor premature termination codons (PTCs) or rare CFTR variants with limited treatment options. Although the clinical modulator response can be reliably predicted using primary airway epithelial cells, primary cells carrying rare CFTR variants are scarce. To overcome this obstacle, cell lines can be created by overexpression of mouse Bmi-1 and human TERT (hTERT). Using this approach, we developed 2 non-CF and 6 CF airway epithelial cell lines, 3 of which were homozygous for the W1282X PTC variant. The Bmi-1/hTERT cell lines recapitulated primary cell morphology and ion transport function. The 2 F508del-CFTR cell lines responded robustly to CFTR modulators, which was mirrored in the parent primary cells and in the cell donors’ clinical response. Cereblon E3 ligase modulators targeting eukaryotic release factor 3a (eRF3a) rescued W1282X-CFTR function to approximately 20% of WT levels and, when paired with G418, rescued G542X-CFTR function to approximately 50% of WT levels. Intriguingly, eRF3a degraders also diminished epithelial sodium channel (ENaC) function. These studies demonstrate that Bmi-1/hTERT cell lines faithfully mirrored primary cell responses to CFTR modulators and illustrate a therapeutic approach to rescue CFTR nonsense mutations.

Epigenome editing of the CFTR-locus for treatment of cystic fibrosis

BACKGROUND

Mechanisms governing the diversity of CFTR gene expression throughout the body are complex. Multiple intronic and distal regulatory elements are responsible for regulating differential CFTR expression across tissues.

METHODS

Drawing on published data, 18 high-priority genomic regions were identified and interrogated for CFTR-enhancer function using CRISPR/dCas9-based epigenome editing tools. Each region was evaluated by dCas9p300 and dCas9KRAB for its ability to enhance or repress CFTR expression, respectively.

RESULTS

Multiple genomic regions were tested for enhancer activity using CRISPR/dCas9 epigenome editing. dCas9p300 mediates a significant increase in CFTR mRNA levels when targeted to the promoter and a region 44 kb upstream of the transcriptional start site in a CFTR-low expressing cell line. Multiple gRNAs targeting the promoter induced a robust increase in CFTR protein levels. In contrast, dCas9KRAB-mediated repression is much more robust with 10 of the 18 evaluated genomic regions inducing CFTR protein knockdown. To evaluate the therapeutic efficacy of modulating CFTR gene regulation, dCas9p300 was used to induce elevated levels of CFTR from the endogenous locus in ΔF508/ΔF508 human bronchial epithelial cells. Ussing chamber studies demonstrated a synergistic increase in ion transport in response to CRISPR-induced expression of ΔF508 CFTR mRNA along with VX809 treatment.

CONCLUSIONS

CRISPR/dCas9-based epigenome-editing provides a previously unexplored tool for interrogating CFTR enhancer function. Here, we demonstrate that therapeutic interventions that increase the expression of CFTR may improve the efficacy of CFTR modulators. A better understanding CFTR regulatory mechanisms could uncover novel therapeutic interventions for the development of cystic fibrosis therapies.

Secretory Cells Dominate Airway CFTR Expression and Function in Human Airway Superficial Epithelia

Rationale: Identification of the specific cell types expressing CFTR (cystic fibrosis [CF] transmembrane conductance regulator) is required for precision medicine therapies for CF. However, a full characterization of CFTR expression in normal human airway epithelia is missing. Objectives: To identify the cell types that contribute to CFTR expression and function within the proximal-distal axis of the normal human lung. Methods: Single-cell RNA (scRNA) sequencing (scRNA-seq) was performed on freshly isolated human large and small airway epithelial cells. scRNA in situ hybridization (ISH) and single-cell qRT-PCR were performed for validation. In vitro culture systems correlated CFTR function with cell types. Lentiviruses were used for cell type-specific transduction of wild-type CFTR in CF cells. Measurements and Main Results: scRNA-seq identified secretory cells as dominating CFTR expression in normal human large and, particularly, small airway superficial epithelia, followed by basal cells. Ionocytes expressed the highest CFTR levels but were rare, whereas the expression in ciliated cells was infrequent and low. scRNA ISH and single-cell qRT-PCR confirmed the scRNA-seq findings. CF lungs exhibited distributions of CFTR and ionocytes similar to those of normal control subjects. CFTR mediated Cl^- secretion in cultures tracked secretory cell, but not ionocyte, densities. Furthermore, the nucleotide-purinergic regulatory system that controls CFTR-mediated hydration was associated with secretory cells and not with ionocytes. Lentiviral transduction of wild-type CFTR produced CFTR-mediated Cl^- secretion in CF airway secretory cells but not in ciliated cells. Conclusions: Secretory cells dominate CFTR expression and function in human airway superficial epithelia. CFTR therapies may need to restore CFTR function to multiple cell types, with a focus on secretory cells.

SARS-CoV-2 infection of the oral cavity and saliva

Despite signs of infection-including taste loss, dry mouth and mucosal lesions such as ulcerations, enanthema and macules-the involvement of the oral cavity in coronavirus disease 2019 (COVID-19) is poorly understood. To address this, we generated and analyzed two single-cell RNA sequencing datasets of the human minor salivary glands and gingiva (9 samples, 13,824 cells), identifying 50 cell clusters. Using integrated cell normalization and annotation, we classified 34 unique cell subpopulations between glands and gingiva. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viral entry factors such as ACE2 and TMPRSS members were broadly enriched in epithelial cells of the glands and oral mucosae. Using orthogonal RNA and protein expression assessments, we confirmed SARS-CoV-2 infection in the glands and mucosae. Saliva from SARS-CoV-2-infected individuals harbored epithelial cells exhibiting ACE2 and TMPRSS expression and sustained SARS-CoV-2 infection. Acellular and cellular salivary fractions from asymptomatic individuals were found to transmit SARS-CoV-2 ex vivo. Matched nasopharyngeal and saliva samples displayed distinct viral shedding dynamics, and salivary viral burden correlated with COVID-19 symptoms, including taste loss. Upon recovery, this asymptomatic cohort exhibited sustained salivary IgG antibodies against SARS-CoV-2. Collectively, these data show that the oral cavity is an important site for SARS-CoV-2 infection and implicate saliva as a potential route of SARS-CoV-2 transmission.

SARS-CoV-2 D614G variant exhibits efficient replication ex vivo and transmission in vivo

The spike aspartic acid-614 to glycine (D614G) substitution is prevalent in global severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) strains, but its effects on viral pathogenesis and transmissibility remain unclear. We engineered a SARS-CoV-2 variant containing this substitution. The variant exhibits more efficient infection, replication, and competitive fitness in primary human airway epithelial cells but maintains similar morphology and in vitro neutralization properties, compared with the ancestral wild-type virus. Infection of human angiotensin-converting enzyme 2 (ACE2) transgenic mice and Syrian hamsters with both viruses resulted in similar viral titers in respiratory tissues and pulmonary disease. However, the D614G variant transmits significantly faster and displayed increased competitive fitness than the wild-type virus in hamsters. These data show that the D614G substitution enhances SARS-CoV-2 infectivity, competitive fitness, and transmission in primary human cells and animal models.

Assessing Human Airway Epithelial Progenitor Cells for Cystic Fibrosis Cell Therapy

Cystic fibrosis (CF) is caused by loss-of-function mutations in the CFTR (CF transmembrane regulator) gene. Pharmacologic therapies directed at CFTR have been developed but are not effective for mutations that result in little or no mRNA or protein expression. Cell therapy is a potential mutation-agnostic approach to treatment. One strategy is to harvest human bronchial epithelial cells (HBECs) for gene addition or genetic correction, followed by expansion and engraftment. This approach will require cells to grow extensively while retaining their ability to reconstitute CFTR activity. We hypothesized that conditionally reprogrammed cell (CRC) technology, namely growth in the presence of irradiated feeder cells and a Rho kinase inhibitor, would enable expansion while maintaining cell capacity to express functional CFTR. Our goal was to compare expression of the basal cell marker NGFR (nerve growth factor receptor) and three-dimensional bronchosphere colony-forming efficiency (CFE) in early- and later-passage HBECs grown using nonproprietary bronchial epithelial growth medium or the CRC method. Cell number and CFTR activity were determined in a competitive repopulation assay employing chimeric air-liquid interface cultures. HBECs expanded using the CRC method expressed the highest NGFR levels, had the greatest 3D colony-forming efficiency at later passage, generated greater cell numbers in chimeric cultures, and most effectively reconstituted CFTR activity. In our study, the HBEC air-liquid interface model, an informative testing platform proven vital for the development of other CF therapies, illustrated that cells grown by CRC technology or equivalent methods may be useful for cell therapy of CF.

SARS-CoV-2 D614G Variant Exhibits Enhanced Replication ex vivo and Earlier Transmission in vivo

The D614G substitution in the S protein is most prevalent SARS-CoV-2 strain circulating globally, but its effects in viral pathogenesis and transmission remain unclear. We engineered SARS-CoV-2 variants harboring the D614G substitution with or without nanoluciferase. The D614G variant replicates more efficiency in primary human proximal airway epithelial cells and is more fit than wildtype (WT) virus in competition studies. With similar morphology to the WT virion, the D614G virus is also more sensitive to SARS-CoV-2 neutralizing antibodies. Infection of human ACE2 transgenic mice and Syrian hamsters with the WT or D614G viruses produced similar titers in respiratory tissue and pulmonary disease. However, the D614G variant exhibited significantly faster droplet transmission between hamsters than the WT virus, early after infection. Our study demonstrated the SARS-CoV2 D614G substitution enhances infectivity, replication fitness, and early transmission.

SARS-CoV-2 Reverse Genetics Reveals a Variable Infection Gradient in the Respiratory Tract

The mode of acquisition and causes for the variable clinical spectrum of coronavirus disease 2019 (COVID-19) remain unknown. We utilized a reverse genetics system to generate a GFP reporter virus to explore severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pathogenesis and a luciferase reporter virus to demonstrate sera collected from SARS and COVID-19 patients exhibited limited cross-CoV neutralization. High-sensitivity RNA in situ mapping revealed the highest angiotensin-converting enzyme 2 (ACE2) expression in the nose with decreasing expression throughout the lower respiratory tract, paralleled by a striking gradient of SARS-CoV-2 infection in proximal (high) versus distal (low) pulmonary epithelial cultures. COVID-19 autopsied lung studies identified focal disease and, congruent with culture data, SARS-CoV-2-infected ciliated and type 2 pneumocyte cells in airway and alveolar regions, respectively. These findings highlight the nasal susceptibility to SARS-CoV-2 with likely subsequent aspiration-mediated virus seeding to the lung in SARS-CoV-2 pathogenesis. These reagents provide a foundation for investigations into virus-host interactions in protective immunity, host susceptibility, and virus pathogenesis.

SARS-CoV-2 Reverse Genetics Reveals a Variable Infection Gradient in the Respiratory Tract

The mode of acquisition and causes for the variable clinical spectrum of coronavirus disease 2019 (COVID-19) remain unknown. We utilized a reverse genetics system to generate a GFP reporter virus to explore severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pathogenesis and a luciferase reporter virus to demonstrate sera collected from SARS and COVID-19 patients exhibited limited cross-CoV neutralization. High-sensitivity RNA in situ mapping revealed the highest angiotensin-converting enzyme 2 (ACE2) expression in the nose with decreasing expression throughout the lower respiratory tract, paralleled by a striking gradient of SARS-CoV-2 infection in proximal (high) versus distal (low) pulmonary epithelial cultures. COVID-19 autopsied lung studies identified focal disease and, congruent with culture data, SARS-CoV-2-infected ciliated and type 2 pneumocyte cells in airway and alveolar regions, respectively. These findings highlight the nasal susceptibility to SARS-CoV-2 with likely subsequent aspiration-mediated virus seeding to the lung in SARS-CoV-2 pathogenesis. These reagents provide a foundation for investigations into virus-host interactions in protective immunity, host susceptibility, and virus pathogenesis.

Mometasone absorption in cultured airway epithelium

BACKGROUND

Topical mometasone is frequently used as an intranasal spray, on drug-eluting stents, and compounded by specialty pharmacies as a sinus rinse. A typical sinus rinse contains 1.2 mg of mometasone dissolved in 240 mL of buffered saline and is flushed through the sinonasal cavity. The mometasone irrigation rapidly flows to the contralateral sinonasal cavity or the nasopharynx with a contact time on the order of 5 to 10 seconds. However, no information is available on the absorption rate of topical mometasone on the sinonasal surface.

METHODS

To determine the absorption characteristics of mometasone, we harvested nasal epithelium from 2 healthy donors and differentiated them into a mature ciliated epithelium on Millicell membranes. We applied mometasone to the apical surface for various time intervals and then rinsed off non-absorbed mometasone with phosphate-buffered saline. Millicell membranes with the adherent epithelial cells were then harvested and stored in guanidine hydrochloride for quantification using high-performance liquid chromatography-mass spectrometry.

RESULTS

Fifty percent of the maximal absorption occurred after an average of 38 minutes after application, and maximal absorption occurred after an average of 114 minutes.

CONCLUSION

Our data provide an estimate for rates of absorption of mometasone applied to the sinonasal cavity and suggest that the absorption rates poorly match contact time during saline lavage.

Challenges Facing Airway Epithelial Cell-Based Therapy for Cystic Fibrosis

Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene cause the life-limiting hereditary disease, cystic fibrosis (CF). Decreased or absent functional CFTR protein in airway epithelial cells leads to abnormally viscous mucus and impaired mucociliary transport, resulting in bacterial infections and inflammation causing progressive lung damage. There are more than 2000 known variants in the CFTR gene. A subset of CF individuals with specific CFTR mutations qualify for pharmacotherapies of variable efficacy. These drugs, termed CFTR modulators, address key defects in protein folding, trafficking, abundance, and function at the apical cell membrane resulting from specific CFTR mutations. However, some CFTR mutations result in little or no CFTR mRNA or protein expression for which a pharmaceutical strategy is more challenging and remote. One approach to rescue CFTR function in the airway epithelium is to replace cells that carry a mutant CFTR sequence with cells that express a normal copy of the gene. Cell-based therapy theoretically has the potential to serve as a one-time cure for CF lung disease regardless of the causative CFTR mutation. In this review, we explore major challenges and recent progress toward this ambitious goal. The ideal therapeutic cell would: (1) be autologous to avoid the complications of rejection and immune-suppression; (2) be safely modified to express functional CFTR; (3) be expandable ex vivo to generate sufficient cell quantities to restore CFTR function; and (4) have the capacity to engraft, proliferate and persist long-term in recipient airways without complications. Herein, we explore human bronchial epithelial cells (HBECs) and induced pluripotent stem cells (iPSCs) as candidate cell therapies for CF and explore the challenges facing their delivery to the human airway.

Diatom assemblages promote ice formation in large lakes

We present evidence for the directed formation of ice by planktonic communities dominated by filamentous diatoms sampled from the ice-covered Laurentian Great Lakes. We hypothesize that ice formation promotes attachment of these non-motile phytoplankton to overlying ice, thereby maintaining a favorable position for the diatoms in the photic zone. However, it is unclear whether the diatoms themselves are responsible for ice nucleation. Scanning electron microscopy revealed associations of bacterial epiphytes with the dominant diatoms of the phytoplankton assemblage, and bacteria isolated from the phytoplankton showed elevated temperatures of crystallization (T(c)) as high as -3 °C. Ice nucleation-active bacteria were identified as belonging to the genus Pseudomonas, but we could not demonstrate that they were sufficiently abundant to incite the observed freezing. Regardless of the source of ice nucleation activity, the resulting production of frazil ice may provide a means for the diatoms to be recruited to the overlying lake ice, thereby increasing their fitness. Bacterial epiphytes are likewise expected to benefit from their association with the diatoms as recipients of organic carbon excreted by their hosts. This novel mechanism illuminates a previously undescribed stage of the life cycle of the meroplanktonic diatoms that bloom in Lake Erie and other Great Lakes during winter and offers a model relevant to aquatic ecosystems having seasonal ice cover around the world.

Are routine peritoneal fluid cultures during appendicectomy justified?

BACKGROUND

To determine the impact of obtaining routine peritoneal fluid cultures during appendicectomy, on the treatment and the clinical outcomes.

METHODS

The case notes of 137 consecutive patients having appendicectomy, selected from the microbiology database over a period of 1 year were reviewed. The microorganisms in peritoneal cultures, selection of antibiotics and clinical outcomes were recorded. Patients were subdivided into two groups; group I: uncomplicated appendicitis and group II: complicated appendicitis.

RESULTS

The study included 137 patients with a median age of 19 years. Cultures were obtained from 79.5% of patients (group I: 67/84, group II: 42/53). Cultures were positive in 28.3% (19/67) patients in group I and 69% (29/ 42) in group II. Wound infection (5.6%), prolonged ileus (7.5%) and intra-abdominal abscess (3.7%) were the recorded complications in group II. Antibiotics were modified in 3 out of 109 patients.

CONCLUSION

Intra-operative peritoneal cultures during appendicectomy do not significantly contribute towards patient management.

Habitat requirements of the seabird tick, Ixodes uriae (Acari: Ixodidae), from the Antarctic Peninsula in relation to water balance characteristics of eggs, nonfed and engorged stages

The seabird tick Ixodes uriae is exposed to extreme environmental conditions during the off-host phase of its life cycle on the Antarctic Peninsula. To investigate how this tick resists desiccation, water requirements of each developmental stage were determined. Features of I. uriae water balance include a high percentage body water content, low dehydration tolerance limit, and a high water loss rate, which are characteristics that classify this tick as hydrophilic. Like other ticks, I. uriae relies on water vapor uptake as an unfed larva and enhanced water retention in the adult, while nymphs are intermediate and exploit both strategies. Stages that do not absorb water vapor, eggs, fed larvae and fed nymphs, rely on water conservation. Other noteworthy features include heat sensitivity that promotes water loss in eggs and unfed larvae, an inability to drink free water from droplets, and behavioral regulation of water loss by formation of clusters. We conclude that I. uriae is adapted for life in a moisture-rich environment, and this requirement is met by clustering in moist, hydrating, microhabitats under rocks and debris that contain moisture levels that are higher than the tick's critical equilibrium activity.

Anoxia tolerance and freeze tolerance in hatchling turtles

Freezing survival in hatchling turtles may be limited by ischemic anoxia in frozen tissues and the associated accumulation of lactate and reactive oxygen species (ROS). To determine whether mechanisms for coping with anoxia are also important in freeze tolerance, we examined the association between capacities for freezing survival and anoxia tolerance in hatchlings of seven species of turtles. Tolerance to freezing (-2.5 degrees C) was high in Emydoidea blandingii, Chrysemys picta, Terrapene ornata, and Malaclemys terrapin and low in Graptemys geographica, Chelydra serpentina, and Trachemys scripta. Hatchlings survived in a N(2) atmosphere at 4 degrees C for periods ranging from 17 d (M. terrapin) to 50 d (G. geographica), but survival time was not associated with freeze tolerance. Lactate accumulated during both stresses, but plasma levels in frozen/thawed turtles were well below those found in anoxia-exposed animals. Activity of the antioxidant enzyme catalase in liver increased markedly with anoxia exposure in most species, but increased with freezing/thawing only in species with low freeze tolerance. Our results suggest that whereas oxygen deprivation occurs during somatic freezing, freeze tolerance is not limited by anoxia tolerance in hatchling turtles.

Adaptations to terrestrial overwintering of hatchling northern map turtles, Graptemys geographica

We conducted a 3-year field and laboratory study of winter biology in hatchlings of the northern map turtle ( Graptemys geographica). At our study area in northern Indiana, hatchlings routinely overwintered in their natal nests, emerging after the weather warmed in spring. Winter survival was excellent despite the fact that hatchlings were exposed frequently to subfreezing temperatures (to -5.4 degrees C). In the laboratory, cold-acclimated hatchlings exhibited low rates of evaporative water loss (mean=2.0 mg g(-1) day(-1)), which would enable them to conserve body water during winter. Laboratory-reared hatchlings were intolerant of freezing at -2.5 degrees C for 24 h, conditions that are readily survived by freeze-tolerant species of turtles. Winter survival of hatchling G. geographica probably depended on their extensive capacity for supercooling (to -14.8 degrees C) and their well-developed resistance to inoculative freezing, which may occur when hatchlings contact ice and ice-nucleating agents present in nesting soil. Supercooled hatchlings survived a brief exposure to -8 degrees C. Others, held at -6 degrees C for 5 days, maintained ATP concentrations at control levels, although they did accumulate lactate and glucose, probably in response to tissue hypoxia. Therefore, anoxia tolerance, as evidenced by the viability of hatchlings exposed to N(2) gas for 8 days, may promote survival during exposure to subfreezing temperatures.

Acquisition of freezing tolerance in early autumn and seasonal changes in gall water content influence inoculative freezing of gall fly larvae, Eurosta solidaginis (Diptera, Tephritidae)

We examined seasonal changes in freeze tolerance and the susceptibility of larvae of the gall fly, Eurosta solidaginis to inoculative freezing within the goldenrod gall (Solidago sp.). In late September, when the water content of the galls was high (approximately 55%), more than half of the larvae froze within their galls when held at -2.5 degrees C for 24 h, and nearly all larvae froze at -4 or -6 degrees C. At this time, most larvae survived freezing at > or = -4 degrees C. By October plants had senesced, and their water content had decreased to 33%. Correspondingly, the number of larvae that froze by inoculation at -4 and -6 degrees C also decreased, however the proportion of larvae that survived freezing increased markedly. Gall water content reached its lowest value (10%) in November, when few larvae froze during exposure to subzero temperatures > or = -6 degrees C. In winter, rain and melting snow transiently increased gall water content to values as high as 64% causing many larvae to freeze when exposed to temperatures as high as -4 degrees C. However, in the absence of precipitation, gall tissues dried and, as before, larvae were not likely to freeze by inoculation. Consequently, in nature larvae freeze earlier in the autumn and/or at higher temperatures than would be predicted based on the temperature of crystallization (T(c)) of isolated larvae. However, even in early September when environmental temperatures are relatively high, larvae exhibited limited levels of freezing tolerance sufficient to protect them if they did freeze.

Validating motivational readiness for exercise behavior with adolescents

The stages of motivational readiness as conceptualized by the Transtheoretical Model have been widely used among adult samples to assess readiness for adopting exercise behavior. To date, little research has been conducted using a staging framework with adolescent samples. There is a need for validation of the staging framework prior to a substantial amount of research with this age group. The current article presents two studies assessing stage and reported exercise behavior (Study 1: n = 819; M age = 15.0 years, SD = 1.2; 51% men; Study 2: n = 184; M age = 18.6 years, SD = .5; 45% men). As hypothesized in both studies, reported exercise consistently varied as a function of stage classification; those in earlier stages of readiness reported less exercise than those in later stages. Staging algorithms showed good sensitivity to detect reported exercise; however, specificity was distinctly better with the algorithm that used a specific activity criterion and immediate intention, as opposed to irregular behavior, in defining the preparation stage. Results support the validity of the staging framework for measuring motivational readiness for exercise behavior among North American adolescents.

The relation between community bans of self-service tobacco displays and store environment and between tobacco accessibility and merchant incentives

OBJECTIVES

These studies investigated (1) the effect of community bans of self-service tobacco displays on store environment and (2) the effect of consumer tobacco accessibility on merchants.

METHODS

We counted cigarette displays (self-service, clerk-assisted, clear acrylic case) in 586 California stores. Merchant interviews (N = 198) identified consumer tobacco accessibility, tobacco company incentives, and shoplifting.

RESULTS

Stores in communities with self-service tobacco display bans had fewer self-service displays and more acrylic displays but an equal total number of displays. The merchants who limited consumer tobacco accessibility received fewer incentives and reported lower shoplifting losses. In contrast, consumer access to tobacco was unrelated to the amount of monetary incentives.

CONCLUSIONS

Community bans decreased self-service tobacco displays; however, exposure to tobacco advertising in acrylic displays remained high. Reducing consumer tobacco accessibility may reduce shoplifting.

Intracellular freezing, viability, and composition of fat body cells from freeze-intolerant larvae of Sarcophaga crassipalpis

Although it is often assumed that survival of freezing requires that ice formation must be restricted to extracellular compartments, fat body cells from freeze-tolerant larvae of the gall fly, Eurosta solidaginis (Diptera, Tephritidae) survive intracellular freezing. Furthermore, these cells are highly susceptible to inoculative freezing by external ice, undergo extensive lipid coalescence upon thawing, and survive freezing better when glycerol is added to the suspension medium. To determine whether these traits are required for intracellular freeze tolerance or whether they are incidental and possessed by fat body cells in general, we investigated the capacity of fat body cells from nondiapause-destined and diapause-destined (i.e., cold-hardy) larvae of the freeze-intolerant flesh fly Sarcophaga crassipalpis (Diptera, Sarcophagidae) to survive intracellular freezing. Fat body cells from both types of larvae were highly susceptible to inoculative freezing; all cells froze between -3.7 to -6.2 degrees C. The highest rates for survival of intracellular freezing occurred at -5 degrees C. The addition of glycerol to the media markedly increased survival rates. Upon thawing, the fat body cells showed little or no lipid coalescence. Fat body cells from E. solidaginis had a water content of only 35% compared to cells from S. crassipalpis larvae that had 52-55%; cells with less water may be less likely to be damaged by mechanical forces during intracellular freezing.

A prospective analysis of the relationship between walking and mood in sedentary ethnic minority women

Walking for exercise is becoming widely recognized for bestowing health benefits. This study examined the association of walking for exercise and mood in sedentary, ethnic minority women over a five-month period. Ethnic minority women (N = 102) participated in a randomized, controlled trial of a 7-week behaviorally based telephone and mail intervention that promoted the adoption of walking for exercise compared to a non-behavioral minimal intervention. At 2-month post-test and 5-month follow-up, participants reported significant decreases in depressive mood and increases in vigor. Increase in walking over the course of the study was associated with change in vigor. Limited evidence was found to support a relationship between walking for exercise and mood improvement in ethnic-minority women.

Cigarette advertising and promotional strategies in retail outlets: results of a statewide survey in California

OBJECTIVE

To examine the extent and types of cigarette advertising materials in stores and to assess tobacco company compliance with the 1998 Master Settlement Agreement (MSA).

DESIGN

A cross-sectional analysis of a random sample of 586 stores that sold cigarettes.

SETTING

US state of California.

MAIN OUTCOME MEASURES

Trained data collectors classified cigarette advertising materials by type (signs, displays, functional items), location (interior or exterior), and placement (below 3 feet (1 m) or near candy).

RESULTS

California retail outlets featured 17.2 (SD 16.1) tobacco advertising materials on average, and 94% of stores featured at least some advertising. About 85% of these were within 4 feet (1.3 m) of the counter. About 50% of the stores had ads at or below 3 feet, and 23% had cigarette product displays next to candy. In violation of the MSA, 3% of stores featured signs with cartoons and 11% had large exterior signs.

CONCLUSIONS

Tobacco companies are aggressively using stores to market cigarettes. Moreover, the spirit of the MSA-to protect children from cigarette advertising-has not been realised. Future studies should monitor industry use of this venue and assess the impact of exposure to cigarette advertising materials in stores on adult smokers and youth.

Physiological responses to supercooling and hypoxia in the hatchling painted turtle, Chrysemys picta

We investigated physiological responses to supercooling in hatchling painted turtles (Chrysemys picta) which remain in their natal nests over winter and therefore may become exposed to subzero temperatures. These turtles are freeze tolerant but also must rely on supercooling to survive exposure to the lower temperatures occurring in nests during winter. We compared whole-body concentrations of lactate, glucose, glycerol, and ATP in turtles chilled at 0 degrees C, -4 degrees C, or -6 degrees C for 5 days, or at 6 degrees C for 19 days. In a companion experiment, we measured metabolite concentrations in turtles exposed to a hypoxic environment for 1 day, 4 days, or 8 days. Supercooling and hypoxia exposure were both associated with an increase in concentrations of lactate and glucose and a decrease in glycerol concentrations (albeit no change in the ATP pool), suggesting that supercooling induces functional hypoxia. We conclude that hypoxia tolerance may be an important pre-adaptation for surviving exposure to subzero temperatures in hatchling C. picta.

Rapid cold-hardening of Drosophila melanogaster (Diptera: Drosophiladae) during ecologically based thermoperiodic cycles

In contrast to most studies of rapid cold-hardening, in which abrupt transfers to low temperatures are used to induce an acclimatory response, the primary objectives of this study were to determine (i) whether rapid cold-hardening was induced during the cooling phase of an ecologically based thermoperiod, (ii) whether the protection afforded was lost during warming or contributed to increased cold-tolerance during subsequent cycles and (iii) whether the major thermally inducible stress protein (Hsp70) or carbohydrate cryoprotectants contributed to the protection afforded by rapid cold-hardening. During the cooling phase of a single ecologically based thermoperiod, the tolerance of Drosophila melanogaster to 1 h at −7 degrees C increased from 5 +/− 5% survival to 62.5 +/− 7.3% (means +/− S.E.M., N=40-60), while their critical thermal minima (CTmin) decreased by 1.9 degrees C. Cold hardiness increased with the number of thermoperiods to which flies were exposed; i.e. flies exposed to six thermoperiods were more cold-tolerant than those exposed to two. Endogenous levels of Hsp70 and carbohydrate cryoprotectants were unchanged in rapidly cold-hardened adults compared with controls held at a constant 23 degrees C. In nature, rapid cold-hardening probably affords subtle benefits during short-term cooling, such as allowing D. melanogaster to remain active at lower temperatures than they otherwise could.

Biological ice nucleation and ice distribution in cold-hardy ectothermic animals

For many ectotherms, overwintering survival depends on the avoidance or regulation of ice nucleation and growth within their body fluids. Freeze avoidance via supercooling plays an important role in the cold hardiness of many small species, particularly terrestrial arthropods, that do not survive the freezing of their body fluids. In contrast, mechanisms that limit supercooling and initiate freezing at relatively high temperatures promote survival of the few invertebrates and vertebrates that tolerate freezing. These mechanisms include inoculative freezing, which results from contact with ice in the environment, and various ice nucleating proteins, microbes, and crystalloid compounds. In freeze-tolerant ectotherms, cold hardiness is influenced by complex, seasonally changing interactions among physiological factors, ice nucleators, and the physical microenvironment. Extraorgan sequestration of ice is a major adaptation of freeze tolerance. For most freeze-tolerant species, ice growth is primarily restricted to extracellular compartments; however, intracellular freezing also occurs in some species.

Diapause development in frozen larvae of the goldenrod gall fly, Eurosta solidaginis fitch (diptera: tephritidae)

Seasonal changes in metabolic rate and the potential for morphological development demonstrated that third-instar larvae of the goldenrod gall fly, Eurosta solidaginis Fitch, exhibit a distinct winter diapause. Metabolic rate (CO2 production) was significantly lower from 15 October to 9 February than in early autumn (9 September) and spring (1 March) samples. The induction of diapause coincided with the development of cold-hardening, maximum larval mass, and gall senescence, but our experiments did not identify specific cues triggering diapause induction. We examined the influence of exposure to 0 degrees C and -20 degrees C on diapause development. Diapause development in larvae stored at 0 degrees C occurred at approximately the same rate as in nature. Until 15 December the larvae were in the refractory phase of diapause (incapable of morphological development, even at permissive temperatures), but afterward moved to the activated phase within which diapause intensity decreased until termination in February. Diapause development occurred in larvae collected during the winter and stored at -20 degrees C for periods of 1 week to 3 months. Diapause intensity decreased in frozen larvae through the winter but at a slower rate than in larvae stored at 0 degrees C.

Functional phosphorylation sites in the C-terminal region of the multivalent multifunctional transcriptional factor CTCF

CTCF is a widely expressed and highly conserved multi-Zn-finger (ZF) nuclear factor. Binding to various CTCF target sites (CTSs) is mediated by combinatorial contributions of different ZFs. Different CTSs mediate distinct CTCF functions in transcriptional regulation, including promoter repression or activation and hormone-responsive gene silencing. In addition, the necessary and sufficient core sequences of diverse enhancer-blocking (insulator) elements, including CpG methylation-sensitive ones, have recently been pinpointed to CTSs. To determine whether a posttranslational modification may modulate CTCF functions, we studied CTCF phosphorylation. We demonstrated that most of the modifications that occur at the carboxy terminus in vivo can be reproduced in vitro with casein kinase II (CKII). Major modification sites map to four serines within the S(604)KKEDS(609)S(610)DS(612)E motif that is highly conserved in vertebrates. Specific mutations of these serines abrogate phosphorylation of CTCF in vivo and CKII-induced phosphorylation in vitro. In addition, we showed that completely preventing phosphorylation by substituting all serines within this site resulted in markedly enhanced repression of the CTS-bearing vertebrate c-myc promoters, but did not alter CTCF nuclear localization or in vitro DNA-binding characteristics assayed with c-myc CTSs. Moreover, these substitutions manifested a profound effect on negative cell growth regulation by wild-type CTCF. CKII may thus be responsible for attenuation of CTCF activity, either acting on its own or by providing the signal for phosphorylation by other kinases and for CTCF-interacting protein partners.

Seasonal changes in physiology and development of cold hardiness in the hatchling painted turtle Chrysemys picta

Hatchling painted turtles (Chrysemys picta) commonly hibernate in shallow, natal nests where winter temperatures may fall below −10 degrees C. Although hatchlings are moderately freeze-tolerant, they apparently rely on supercooling to survive exposure to severe cold. We investigated seasonal changes in physiology and in the development of supercooling capacity and resistance to inoculative freezing in hatchling Chrysemys picta exposed in the laboratory to temperatures that decreased from 22 to 4 degrees C over a 5.5 month period. For comparison, we also studied hatchling snapping turtles (Chelydra serpentina), a less cold-hardy species that usually overwinters under water. Although Chrysemys picta and Chelydra serpentina differed in some physiological responses, both species lost dry mass, catabolized lipid and tended to gain body water during the acclimation regimen. Recently hatched, 22 degrees C-acclimated Chrysemys picta supercooled only modestly (mean temperature of crystallization −6.3+/−0.2 degrees C; N=6) and were susceptible to inoculation by ice nuclei in a frozen substratum (mean temperature of crystallization −1.1+/−0.1 degrees C; N=6) (means +/− s.e.m.). In contrast, cold-acclimated turtles exhibited pronounced capacities for supercooling and resistance to inoculative freezing. The development of cold hardiness reflected the elimination or deactivation of potent endogenous ice nuclei and an elevation of blood osmolality that was due primarily to the retention of urea, but was not associated with accumulation of the polyols, sugars or amino acids commonly found in the cryoprotection systems of other animals. Also, Chrysemys picta (and Chelydra serpentina) lacked both antifreeze proteins and ice-nucleating proteins, which are used by some animals to promote supercooling and to initiate freezing at the high temperatures conducive to freezing survival, respectively.

Isoniazid affects multiple components of the type II fatty acid synthase system of Mycobacterium tuberculosis

Genetic and biochemical evidence has implicated two different target enzymes for isoniazid (INH) within the unique type II fatty acid synthase (FAS) system involved in the production of mycolic acids. These two components are an enoyl acyl carrier protein (ACP) reductase, InhA, and a beta-ketoacyl-ACP synthase, KasA. We compared the consequences of INH treatment of Mycobacterium tuberculosis (MTB) with two inhibitors having well-defined targets: triclosan (TRC), which inhibits InhA; and thiolactomycin (TLM), which inhibits KasA. INH and TLM, but not TRC, upregulate the expression of an operon containing five FAS II components, including kasA and acpM. Although all three compounds inhibit mycolic acid synthesis, treatment with INH and TLM, but not with TRC, results in the accumulation of ACP-bound lipid precursors to mycolic acids that were 26 carbons long and fully saturated. TLM-resistant mutants of MTB were more cross-resistant to INH than TRC-resistant mutants. Overexpression of KasA conferred more resistance to TLM and INH than to TRC. Overexpression of InhA conferred more resistance to TRC than to INH and TLM. Co-overexpression of both InhA and KasA resulted in strongly enhanced levels of INH resistance, in addition to cross-resistance to both TLM and TRC. These results suggest that these components of the FAS II complex are not independently regulated and that alterations in the expression level of InhA affect expression levels of KasA. Nonetheless, INH appeared to resemble TLM more closely in overall mode of action, and KasA levels appeared to be tightly correlated with INH sensitivity.

Clinical assessment using the Clinical Rating Scale: Thomas and Olson revisited

Does the Clinical Rating Scale retain its validity when it is used, not by researchers, but by psychotherapists in their clinical practice? Students in a marital and family therapy training center routinely used the Clinical Rating Scale as part of the intake process. Although they had modest training in its use, confirmatory factor analysis indicated that they produced data that provided a reasonable approximation of the underlying factor structure. Therefore, although primarily considered a research instrument, the Clinical Rating Scale may have a role in clinical assessment and treatment planning.

Mild winter temperatures reduce survival and potential fecundity of the goldenrod gall fly, Eurosta solidaginis (Diptera: Tephritidae)

We tested the hypothesis that mild winter temperatures are detrimental to the survival and reproductive potential of insects. We measured survival, body size, and potential fecundity of a freeze tolerant insect, the goldenrod gall fly (Eurosta solidaginis), after overwintering in the laboratory for ~3 mo. frozen at -22 degrees C, unfrozen at 0 degrees C, or unfrozen at 12 degrees C. Larvae held at 12 degrees C suffered high mortality (70%) and relatively low potential fecundity as adults (mean+/-SEM=199+/-11 eggs/female), while those held at 0 degrees C had both low mortality (11%) and high potential fecundity (256+/-15 eggs/female). Freezing (-22 degrees C) increased mortality (30% overall) but did not significantly reduce fecundity (245+/-13 eggs/female). Egg length and width were constant regardless of treatment group or female body size. Analysis of covariance indicated that reduced fecundity in the 12 degrees C group was related to reduced larval body weight following treatment. Patterns of larval weight loss in the experimental treatments were generally correlated with previous reports of latitudinal trends in weight loss through the winter. We conclude that mild winter temperatures may be detrimental to some overwintering insects, particularly species that do not feed following winter diapause. Low temperature and even freezing are beneficial, allowing conservation of energy reserves to maintain high survival and potential fecundity.

Identification of ice-nucleating active Pseudomonas fluorescens strains for biological control of overwintering Colorado potato beetles (Coleoptera: Chrysomelidae)

Laboratory studies were conducted to identify ice-nucleating active bacterial strains able to elevate the supercooling point, the temperature at which freezing is initiated in body fluids, of Colorado potato beetles, Leptinotarsa decemlineata (Say), and to persist in their gut. Adult beetles fed ice-nucleating active strains of Pseudomonas fluorescens, P. putida, or P. syringae at 10(6) or 10(3) bacterial cells per beetle had significantly elevated supercooling points, from -4.5 to -5.7 degrees C and from -5.2 to -6.6 degrees C, respectively, immediately after ingestion. In contrast, mean supercooling point of untreated control beetles was -9.2 degrees C. When sampled at 2 and 12 wk after ingestion, only beetles fed P. fluorescens F26-4C and 88-335 still had significantly elevated supercooling points, indicating that these strains of bacteria were retained. Furthermore, beetle supercooling points were comparable to those observed immediately after ingestion, suggesting that beetle gut conditions were favorable not only for colonization but also for expression of ice-nucleating activity by these two strains. The results obtained from exposure to a single, low dose of either bacterial strain also show that a minimum amount of inoculum is sufficient for establishment of the bacterium in the gut. Persistence of these bacteria in Colorado potato beetles long after ingestion was also confirmed using a polymerase chain reaction technique that detected ice-nucleating active bacteria by virtue of their ina genes. Application of these ice-nucleating active bacteria to elevate the supercooling point of this freeze-intolerant insect pest could significantly reduce their winter survival, thereby reducing local populations and, consequently, crop damage.

Extreme resistance to desiccation in overwintering larvae of the gall fly Eurosta solidaginis (Diptera, tephritidae)

During winter, larvae of the goldenrod gall fly Eurosta solidaginis are exposed for extended periods to severe low ambient temperatures and low humidities within plant galls. The resistance of these larvae to desiccation at various temperatures and humidities, the transition (critical) temperature, and the effects of treatment with organic solvents on the larval rates of water loss and on changes in osmolality during desiccation were examined. The water loss rates of the flesh fly Sarcophaga crassipalpis under desiccating conditions were also measured. The water permeability of the cuticle of E. solidaginis larvae was very low (0.038 microgram h(−1)cm(−2)Pa(−1) at 20 C and 4% relative humidity) compared with that of larvae of other species. The value for E. solidaginis is equivalent to that of the very drought-resistant larvae of the tenebrionid beetle Tenebrio molitor (0.038 microgram h(−1)cm(−2)Pa(−1) at 30 C). In contrast, the permeability of larvae of the flesh fly Sarcophaga crassipalpis at 20 C and 4 % relative humidity was 0.331 microgram h(−1) cm(−2)Pa(−1). The thermal dependence of the cuticular permeability increased with temperature by approximately 0.0010 +microgram h(−1) cm(−2)Pa(−1) C(−1) in the interval between 4 and 40 C. At the transition temperature of 40 C, the thermal dependence of the permeability increased abruptly to 0.0400 microgram h(−1)cm(−2)Pa(−1) C(−1). Larvae treated with hexane and acetone remained remarkably resistant to water loss. However, treatment with chloroform:methanol increased the water loss rate approximately 25-fold. During desiccation at 4 C and 4% relative humidity for 21 days, E. solidaginis larvae showed a mass loss of 18.5+/−4.4 % (mean +/− s.e.m., N=6). Animals dried under the same conditions over the same period showed a haemolymph osmolality of 851+/−75 mosmol kg(−1) (N=4). Larvae freshly removed from the galls showed a haemolymph osmolality of 918+/−67 mosmol kg(−1)(N=3). A higher osmolality in the dried compared with the fresh larvae would have been expected. The present observation suggests that important ions in the haemolymph may have been excreted or rendered osmotically inactive during desiccation.

Use of genomics and combinatorial chemistry in the development of new antimycobacterial drugs

With the completion of the genome of Mycobacterium tuberculosis comes the promise of a new generation of potent drugs to combat the emerging epidemic of multiply drug-resistant isolates. Translating this genomic information into realistic assays, valid targets, and preclinical drug candidates represents the next great hope in tuberculosis control. We propose a paradigm for exploiting the genome to inform the development of novel antituberculars, utilizing the techniques of differential gene expression as monitored by DNA microarrays coupled with the emerging discipline of combinatorial chemistry. A comparison of currently used antituberculars with the properties of other pharmaceuticals suggests that such compounds will have a defined range of physiochemical properties. In general, we can expect the next generation of antituberculars to be small, relatively hydrophilic molecules that bind tightly to specific cellular targets. Many current antimycobacterials require some form of cellular activation (e.g. the activation of isoniazid by a catalase-peroxidase). Activation corresponds to the oxidative, reductive, or hydrolytic unmasking of reactive groups, which occurs with many current antimycobacterial prodrugs. Understanding the mechanisms involved in activation of current antimycobacterial therapeutics also may facilitate the development of alternative activation strategies or of analogs that require no such processes.

Trans rectal ultrasound guided radioactive seed implant: the Sumter experience

108 patients were treated between 1/06/97 and 7/19/99. Ages ranged from 53 years to 82 years. Pretreatment PSA ranged from 4.0 to 34.6 and post treatment PSA from 0 to 7.3. Given the fact that carcinoma of the prostate is a relatively slow growing tumor and that long survival times are not uncommon even in the face of relatively advanced disease, our treatment team believes that the preferred method of treatment in otherwise healthy patients who have a 20 year life expectancy is radical surgery. We do believe that brachytherapy has a role in the treatment of organ-confined disease and may possibly be proven to be as effective as surgery; however, until there is at least 15-year data, it cannot be considered as the primary treatment of choice in young men. The senior author has stressed the term "treatment team" in this paper for a reason. We sincerely believe that the best results for our patients are obtained when we approach the treatment of the patient as a unified team that makes use of our individual talents and training for the good of the patient as a whole. Each member of the team performs the procedures that he is best trained to do, and we are consistent in our approach and advice to our patients regardless of our disciplines.

Long-term retention of ice-nucleating active Pseudomonas fluorescens by overwintering colorado potato beetles

Ice nucleating-active Pseudomonas fluorescens F264C was fed to Colorado potato beetles to determine bacterial retentioin in the beetle gut and its effect on the cold hardiness of this insect pest. The bacrterium was present in beetles recovered after overwintering in the field, seven months after their exposure to P. fluorescens. Retention was evident not only in the detection of the P. fluorescens ice nucleating gene, inaW, in bacterial cultures from beetle guts but also in the elevated supercooling points of some treated beetles.

Electrophysiological and ultrastructural correlates of cryoinjury in sciatic nerve of the freeze-tolerant wood frog, Rana sylvatica

We investigated function and ultrastructure of sciatic nerves isolated from wood frogs (Rana sylvatica) endemic to the Northwest Territories, Canada, following freezing at -2.5 degrees C, -5.0 degrees C, or -7.5 degrees C. All frogs frozen at -2.5 degrees C, and most frogs (71%) frozen at -5.0 degrees C, recovered within 14 h after thawing began; however, frogs did not survive exposure to -7.5 degrees C. Sciatic nerves isolated from frogs frozen at -7.5 degrees C were refractory to electrical stimulation, whereas those obtained from frogs surviving exposure to -2.5 degrees C or -5.0 degrees C generally exhibited normal characteristics of compound action potentials. Frogs responded to freezing by mobilizing hepatic glycogen reserves to synthesize the cryoprotectant glucose, which increased 20-fold in the liver and 40-fold in the blood. Ultrastructural analyses of nerves harvested from frogs in each treatment group revealed that freezing at -2.5 degrees C or -5.0 degrees C had little or no effect on tissue and cellular organization, but that (lethal) exposure to -7.5 degrees C resulted in marked shrinkage of the axon, degeneration of mitochondria within the axoplasm, and extensive delamination of myelin sheaths of the surrounding Schwann cells.

Inoculative freezing by environmental ice nuclei in the freeze-tolerant wood frog, Rana sylvatica

Efficacy of inoculative freezing by ice nuclei in a simulated winter environment was studied in the wood frog (Rana sylvatica), a freeze-tolerant species that overwinters on the forest floor beneath organic detritus. Adult frogs were confined to plastic canisters and cooled to -2 degrees C over 24 hr with their ventral skin in contact with substrate (humic soil hydrated to 40, 10, or 5%, or soil/peat mixture hydrated to 20 or 10%, w/w), or their dorsal skin in contact with damp leaf mould. Whereas only 20% of control frogs cooled in dry, plastic canisters froze, freezing occurred in nearly all (98%) frogs contacting soil or leaf mould. Inoculation was briefly delayed in frogs exposed to drier substrates. Frogs exposed to an unfreezable substrate (humic soil, 5% moisture) themselves froze, apparently due to the action of constituent nuclei which commonly occur in natural materials. Although the surface over which inoculation can occur is greater in larger frogs, inoculation susceptibility was not correlated with body mass in our frogs (mean +/- SE body mass = 14.0 +/- 0.2 g; range, 9.8-17.8 g). We conclude that the high susceptibility to inoculative freezing in R. sylvatica, which is conferred by its moist, highly permeable integument, promotes freeze tolerance by ensuring that inoculation commences at relatively high temperatures.