Receptor cell habituation in the A1 auditory receptor of four noctuoid moths

Moths of both sexes of Empyreuma affinis (=pugione) and Syntomeida epilais (Arctiidae, Ctenuchinae), Maenas jussiae (Arctiidae, Arctiinae) and Spodoptera frugiperda (Noctuidae, Amphipyrinae) were studied. Spike activity in the A1 cell was recorded using a stainless-steel hook electrode from the tympanic nerve in the mesothorax. Acoustic stimuli consisting of 25 and 100 ms pulses at the best frequency for the species and at intensities that evoke A1 cell saturation response were used at repetition rates of 0.5 and 5 Hz for 100 ms stimuli, and between 2 and 20 Hz for 25 ms stimuli. Stimuli at a repetition rate corresponding to a duty cycle of 5 % (25 ms at 2 Hz and 100 ms at 0.5 Hz) did not evoke monotonic changes in the responses of the A1 cell. With 25 ms pulses, rates above 5 Hz evoked an exponential decrease in the number of spikes and an increase in the latency of the responses of all the 37 specimens tested. The response duration showed no apparent change with stimulus repetition rates even at the highest duty cycle used (50 %), i.e. 25 ms at 20 Hz and 100 ms at 5 Hz. The higher the rate of stimulus repetition, the more marked were the changes in the A1 cell responses. In 16 of 17 preparations from two species, habituation had no effect on the adaptation rate in each response, while in seven of eight specimens of another species, the adaptation rate decreased with stimulus repetition. These results, and those from another mechanoreceptor cell, indicate that receptor cell adaptation (changes evoked in the response by a stimulus of constant intensity) and habituation (changes in the responses due to stimulus repetition rate) are two distinctive phenomena. The A1 cell in its habituated state showed an increase in its response to incremental increases in stimulus intensity of 10 dB. This result supports the idea that receptor cell habituation does not seem to be due to fatigue, i.e. to a temporary loss of the ability to respond to stimulation induced in a sensory receptor by continued stimulation.

Prognostic value of gastric intramucosal pH in critically ill children

OBJECTIVE

To determine the association of tonometrically measured gastric intramucosal pH (pHi) to the occurrence of multiple organ dysfunction syndrome (MODS) and death in critically ill children.

DESIGN

Prospective, observational study.

SETTING

Pediatric intensive care unit (ICU) of a teaching children's hospital.

PATIENTS

Fifty-one critically ill children admitted (median age 5.4+/-5 [SD] yrs; range 1 mo to 16 yrs) with the following diagnoses: post major surgery (n=26), sepsis (n=8), multiple trauma (n=5), acute respiratory distress syndrome (n=4), and "miscellaneous" (n=8).

INTERVENTIONS

Placement of a tonometric catheter.

MEASUREMENTS AND MAIN RESULTS

Pediatric Risk of Mortality (PRISM) score and clinical data were collected on admission and pHi daily during their stay in the pediatric ICU. A sigmoid tonometer was used to determine the pHi. Unconditional logistic regression was used to investigate the prognostic value of pHi. On admission, 26 patients presented with low gastric pHi (< or =7.35) and 17 of them had values of <7.30. The mortality rate in children with pHi <7.30 was 47.1% (95% confidence interval, 26.2 to 69) in contrast with an 11.7% mortality rate (95% confidence interval, 4.6 to 26.6) in children having a pHi of > or =7.30 (p=.015). The pHi and PRISM score on admission were independent predictive factors of death. The risk of mortality is increased when the pHi is low (odds ratio=2.5). However, we did not find the pHi to be a predictor for developing MODS.

CONCLUSIONS

Our results show that pHi is an independent predictor of mortality in patients admitted to a pediatric ICU. Although no relationship was observed between the risk of MODS and gastric pHi, the univariate difference of 21% vs. 41% is highly suggestive. The pHi determination is a minimally invasive procedure and well tolerated in children of all ages.

[Outbreak of asthma caused by soybean dust allergy. Clinical and immunologic study of the affected patients]

BACKGROUND

To study the clinical and immunological data of patients affected by a soybean asthma outbreak in Tarragona, Spain.

PATIENTS AND METHODS

Characteristics of previous asthma, emergency rooms records and immediate outcome of 15 patients who attended emergency room departments the epidemic day were recorded. Functional respiratory studies, skin prick tests to aeroallergens, and prick tests, specific IgE and immunoblotting to soybean extracts were performed in all patients.

RESULTS

Thirteen patients were sensitized to soybean proteins. All of them were atopic (most sensitized to house dust mites) and half had started asthma symptoms after their thirties. The epidemic crisis was particularly severe in patients over 50 years, daily chronic asthma, severe obstructive pattern and/or non receiving steroids. Four patients were admitted to intensive care units. Seven patients showed asthma exacerbations (late reactions) 24 h after the beginning of the epidemic crisis. Specific IgE against a 5-6 kD and a 15.5-17 kD soybean proteins was detected in the sera of 8 patients and 10 patients, respectively.

CONCLUSIONS

The outbreak affected atopic patients exposed to soybean dust. The severity of the crisis was related with the previous severity of asthma. Besides the well known 5-6 kD allergenic soybean protein, the 15.5-17 kD protein seems also to be implicated in the sensitization of most of these patients.

Compounding Fumed Silicas into Polydimethylsiloxane: Bound Rubber and Final Aggregate Size

The properties of mechanically mixed suspensions of fumed silicas in polydimethylsiloxane (PDMS) were studied. The work focuses on two aspects: (i) Adsorption of PDMS onto silicas by means of the mechanical mixing of the bulk polymer and untreated or chemically modified fumed silicas. The silica-PDMS suspensions were completely dispersed or only swollen by a solvent, depending on the filler concentration, the silica surface chemistry, and the polymer molecular weight. The bound rubber content of the different preparations was determined by a weight difference technique and by carbon analysis of the samples and was compared with previously reported values in similar systems. (ii) The effect of the mechanical mixing on the final aggregate size of the silica and on the polymer molecular weight distribution. One PDMS and silicas of different surface area and surface chemistry were used. The final size of the aggregates after a long mixing time with the bulk polymer was approximately the same in all cases. Copyright 1997 Academic Press. Copyright 1997Academic Press

Cell kinetics and tumor regression during radiotherapy in head and neck squamous-cell carcinomas

Head and neck squamous-cell carcinoma (HN-SCC) patient management is mainly based on TNM classification and needs be improved by considering other potentially useful prognostic factors. We examined the pre-radiotherapy tumor potential doubling time (Tpot) evaluated after in vivo infusion of bromodeoxyuridine and flow-cytometric analysis and the early clinical tumor regression after 40 Gy (40 Gy-TR). Tpot values and clinical 40 Gy-TR classes (minor and major) were available for 82 HN-SCC patients. Radiation therapy completion was done either with 1 dose per day (conventional regimen) or 2 doses per day (accelerated regimen). Local control was also available for follow-up times above 4 years. We found that major 40 Gy-TR was strongly correlated with fast tumor growth, characterized by Tpot values below 5 days, and that patients with major 40 Gy-TR showed better local control than those with minor 40 Gy-TR, independently from the radiotherapy regimen type. We also found that treatment completion with accelerated radiotherapy gave better local control for patients with major 40 Gy-TR and fast tumor growth than conventional radiotherapy. Multivariate analysis, performed on all patients, assigned an independent prognostic value to Tpot, tumor classification and 40 Gy-TR.

Differential motility stimulation but not growth stimulation or adhesion of metastatic human colorectal carcinoma cells by target organ-derived liver sinusoidal endothelial cells

Liver is the most common distant metastatic site for colorectal cancers and when blood-borne colorectal cancer cells reach the liver, they first encounter hepatic capillary and sinusoidal endothelial cells. Thus we studied differences between highly (HT-29LMM) and poorly (HT-29P) liver-metastatic sublines of human colorectal cancer cells by examining the interactions between tumor cells and liver microvessel endothelial cells. Using hepatic sinusoidal endothelial (HSE) and lung microvessel endothelial (MLE) cell-conditioned medium we measured the growth and motility stimulating activities released from these endothelial cells and adhesion of these cancer cells to the endothelial cells. Differences in the ability of HSE-conditioned medium (HSE-CM) or MLE-conditioned medium (MLE-CM) to stimulate HT-29 cell growth were not observed. There was a small but significant increase in the rate of adhesion of highly metastatic HT-29LMM cells to HSE cell monolayers than poorly metastatic HT-29P cells, but there was no difference in adhesion to MLE cell monolayers. HSE-CM stimulated the motility of highly metastatic colorectal cancer cells to a greater extent than the poorly metastatic cells. Motility-stimulating activity for the colorectal cancer cell lines was not detected in MLE-CM. The HSE-CM motility-stimulating activity for human HT-29 cells was not removed using antibodies against hepatocyte growth factor (HGF/SF), complement component C3 or laminin, indicating that it is not related to these known liver-derived motility factors. The results suggest that the ability of highly metastatic HT-29LMM colorectal cancer cells to colonize the liver is related to their ability to respond to liver sinusoidal endothelial cell-derived motility factors and to a lesser degree to adhere to liver sinusoidal endothelial cells.

Enteral nutrition following total laryngectomy

Body composition was measured in patients who underwent total laryngectomy for carcinoma and who were enterally fed throughout the postoperative period with full liquid artificial mixtures. The intestinal complications were very mild and required no changes in the nutritional program. Body sector sizes remained essentially unchanged until the end of the support, malnutrition did not occur and the postoperative local infection rate was very low. On the contrary, in patients fed with blenderized food, the amount of enteral infusion had to be reduced because of poor tolerance or abdominal discomfort; in this case caloric intake was largely inadequate. Fall in BW and BCM size and increase of TBNa/TBK ratio demonstrated a postoperative impairment of the nutritional status. Furthermore, the postoperative infection rate, the number of days with fever and the length of antibioticotherapy were higher than those observed in patients fed with full liquid mixtures.

Biomaterial-induced alterations of neutrophil superoxide production

Because periprosthetic infection remains a vexing problem for patients receiving implanted devices, we evaluated the effect of several materials on neutrophil free radical production. Human peripheral blood neutrophils were incubated with several sterile, lipopolysaccharide (LPS)-free biomaterials used in surgically implantable prosthetic devices: polyurethane, woven dacron, and velcro. Free radical formation as the superoxide (O2-) anion was evaluated by cytochrome c reduction in neutrophils that were exposed to the materials and then removed and in neutrophils allowed to remain in association with the materials. Neutrophils exposed to polyurethane or woven dacron for 30 or 60 min and then removed consistently exhibited an enhanced release of O2- after simulation via receptor engagement with formyl methionyl-leucyl-phenylalanine. Enhanced reactivity to stimulation via protein kinase C with phorbol myristate acetate, however, was not consistently observed. The cells evaluated for O2- release during continuous association with the biomaterials showed enhanced metabolic activity during short periods of association (especially with polyurethane and woven dacron). Although O2- release by neutrophils in association with these materials decreased with longer periods of incubation, it was not obliterated. These studies, therefore, show that several commonly used biomaterials activate neutrophils soon after exposure and that this activated state diminishes with prolonged exposure but nevertheless remains measurable. The diminishing level of activity with prolonged exposure, however, suggests that ultimately a depletion of reactivity may occur and may result in increased susceptibility to periprosthetic infection.

Chief complaint of 3,545 pediatric patients at the emergency room of San Pablo Hospital during a five months period

A survey was made of the chief complaints at the Emergency Room of San Pablo Hospital of 3,545 pediatric patients seen between January 1 and May 31, 1988. Most common chief complaints involved the gastrointestinal system, trauma, and fractures. There was a wide range of chief complaints. Periodic surveys of this type should be useful in establishing priorities of pediatric training.

Plasma and synovial fluid lanthanides in rheumatoid arthritis: variations after intra-articular therapy

Lanthanides (Ln), or rare earth elements, are detectable in trace amounts in organisms. Increased concentrations of Ln have been observed in rheumatoid arthritis (RA) in plasma (pl) and synovial fluid (Sf). We have evaluated pl and Sf concentrations of Ln (in particular La, Nd, Ce, Yb, Lu, Eu), in rheumatoid arthritis patients, before and after intra-articular steroid injection. Increased pl and Sf concentrations of Ln were confirmed in RA. No detectable synovial fluid concentrations of Ln were observed in healthy controls. A statistically significant Ln reduction (p less than 0.001) was observed in Sf 3 and 6 days after local steroid injection and in pl after 6 days. The decrease in Ln concentrations in Sf and pl, after antiphlogistic therapy, reflects the reduction of the inflammatory condition.

The distribution of arsenic and cobalt in patients with laryngeal carcinoma

The objective of this study was to evaluate tissue and plasma concentrations of arsenic and cobalt in an attempt to discover the role of these elements in the malignant process. Using neutron activation analysis, arsenic and cobalt levels were determined in plasma and in non-malignant and malignant human tissues in 15 patients with laryngeal carcinoma. Arsenic and cobalt levels were about 60% higher in tumor than in adjacent non-malignant tissue (P less than 0.001): arsenic 72.4 +/- 18.0 ng/g versus 43.1 +/- 9.4 in non-malignant tissues, and cobalt 68.7 +/- 7.3 ng/g versus 39.6 +/- 7.0 in non-malignant tissues. Mean plasma arsenic and cobalt levels were also significantly higher in patients with laryngeal carcinoma than in healthy control subjects.

Effects of caponization on body weight, atherosclerosis, and cardiovascular variables in hypertensive and hypotensive turkey lines

Effects of caponization and blood pressure selection on serum lipids, severity of atherosclerosis, body weight, hematocrit, and relative ventricular weight in hypertensive and hypotensive lines of turkeys were evaluated in two trials. At 8 weeks of age, half the turkeys from each line were caponized. Body weights, blood pressure, and blood samples were obtained from each treatment at 8, 20, and 30 weeks of age. A total of 56 and 72 birds were used in Trials 1 and 2, respectively. Birds were necropsied at 30 weeks of age. Hypertensive turkeys had significantly greater serum cholesterol and total lipid than hypotensive turkeys only at 30 weeks of age in Trial 1. Lower relative ventricular weights were observed in hypotensive turkeys within both trials. Hypertensive birds exhibited a more severe degree of atherosclerosis and higher relative heart weight than hypotensive turkeys. Caponization significantly increased total serum lipid only at 20 weeks of age in Trial 2. Average body weight of caponized turkeys was significantly lower (1.2) than the control turkeys at 30 weeks of age. Caponized turkeys exhibited lower relative ventricular weight in Trial 1 but not Trial 2 and an increase in blood pressure only in Trial 2. Caponization suppressed body weight, decreased hematocrit values, and had no significant effect upon plaque severity. The presence or absence of male sex hormones had virtually no effect on proposed atherogenic stimuli thereby suggesting another mechanism by which the female is afforded a higher degree of protection.

Choroid plexus papilloma containing bone

The presence of bone in choroid plexus papillomas is a rare event. The authors report a case of choroid plexus papilloma of the IVth ventricle containing bone in a 18-year-old man, and review two previously reported cases, as well as the mechanisms proposed for the presence of bone and cartilage in neuroepithelial neoplasms.

[Lidocain clearance after oral and intravenous application in rats with low grade ANIT-cholestasis and galactosamine-induced hepatitis (author's transl)]

Each of 6 rats with a low grade of ANIT-cholestasis and a low grade of GalN-hepatitis received either 3 mg Lidocain i.v. or 24 mg Lidocain orally. The plasma concentrations of Lidocain were measured over a period of 3 1/2 hrs. The systemic clearance of Lidocain (Cli.v. = Di.v. divided by AUCi.v.) was significantly increased on ANIT-cholestasis (17 +/- 3) and GalN-hepatitis rats (13 +/- 2) (control rats: 7 +/- 1 ml/min x 100 g bw). Oral clearance of Lidocain (Clor = Dor divided by AUCor) was not significantly different in the three respective groups. In both groups with experimental liver disease the hepatic blood flow--calculated by comparing the systemic to the oral clearance--was significantly increased (22 +/- 4 and 19 +/- 3 vs 8 +/- 1 ml/min x 100 g bw). Due to this increase, the hepatic extraction ratio of Lidocain was significantly decreased (ANIT-cholestasis 0.73 +/- 0.07; GalN-hepatitis 0.74 +/- 0.05; controls 0.85 +/- 0.03). Because of an increase of systemic Lidocain clearance, no toxic plasma concentrations were observed.