[Biophysical foundations of the neuronal activity]

OBJECTIVE

It is sought to expose in a simple but rigorous way the fundamental basis of the classical biophysics.

DEVELOPMENT

I start from the basic properties of a simple system (two solutions separated by a semipermeable membrane) in order to analyze the process of development of differences of potential. It is analyzed with special interest the development of the Nernst and Nernst-Planck equations. Then it is studied how this difference potential can originate, with different ionic species, the resting potential (Goldman, Hodgkin and Katz model). The next step consists in to analyze how the action potential arises. To do this, it will be of capital importance the mathematical model developed by Hodgkin and Huxley in the fifties; for it will be analyzed it thoroughly. Finally, some properties of the ionic channels will be commented that symbolize the biological implementation of the previous model.

CONCLUSION

The fundamental property of the nervous system that constitutes its biological sense is the handling of the information in a quick and sure way. This information codes it basically in form of potentials and its changes. For it, it would be important for clinical neurophysiologists, neurologists, neurosurgeons and psychiatrists to understand the mechanisms that underlie into the behavior of the nervous system.

Biotic indices based on soil nematode communities for assessing soil quality in terrestrial ecosystems

Nematode communities offer several advantages for assessing the quality of soils. Diversity and maturity indices as well as trophic structure defining parameters based on the composition of soil nematode communities have been used to detect various kinds of man-induced disturbances and monitor ecological recovery. In the present paper we examined the response of these indices in herbaceous Mediterranean ecosystems. Incipient soils, which were developed on the top of waste dumping sites were compared with agricultural soils under fallow. Grasslands and old-fields were considered as reference systems. Either diversity or maturity indices were shown to be very sensitive to changes in soil system caused by waste dumping. However, they were less useful for the categorisation of perturbation in agroecosystems. Trophic composition related parameters were more meaningful for this aim. Plant parasite index (PPI) may be a good generic indicator of recovery processes after perturbation in these annual herbaceous ecosystems.

Back-scattered electron imaging of a non-vertebral case of hypervitaminosis A in a cat

We describe a clinical case of hypervitaminosis A in a cat. The main lesions were bony fusions of both the hip and stifle joints, without spinal involvement. A post-mortem study using back-scattered scanning electron microscopy (BEI-SEM) revealed that exostoses had formed around the joints without articular surface involvement. The more recently formed areas of bony proliferation were composed mainly of chondroid tissue surrounded by different degrees of woven bone. As the bony reaction occurred, remodelling of the trabeculae was observed which lead to progressive substitution of chondroid tissue by woven bone surrounded by apposition of lamellar bone. No traces of calcified cartilage were observed in any of the bone sections evaluated.

Effects of sarcoptic mange on serum proteins and immunoglobulin G levels in chamois (Rupicapra pyrenaica) and Spanish ibex (Capra pyrenaica)

Three groups of chamois (Rupicapra pyrenaica) and three groups of Spanish ibex (Capra pyrenaica) were established to study the effects of sarcoptic mange on serum proteins and immunoglobulin G (IgG) levels. The first group of chamois consisted of 22 healthy Pyrenean chamois (R. pyrenaica pyrenaica) from a non-infested area, the second group consisted of 20 healthy Cantabrian chamois (R. p. parva) from an area where sarcoptic mange has been reported since 1994 and the third group consisted of 16 Cantabrian chamois from the same area but naturally infested by Sarcoptes scabiei. The first group of Spanish ibex was 39 healthy animals from a sarcoptic mange non-infested area, the second group was 23 healthy animals from a sarcoptic mange infested area and the third group consisted of 20 animals from the same area but naturally infested with the parasite. Blood samples were taken after killing the animals as part of hunting programmes. Values for total proteins, gamma-globulin and IgG were higher in infested and healthy chamois from the infested area compared to healthy chamois from the non-infested area, and IgG levels were higher in infested chamois compared to healthy-exposed chamois. Values for alpha2-globulin were higher in healthy Cantabrian chamois. In Spanish ibex, albumin, alpha2-globulin and IgG levels were lower in the healthy Spanish ibex from the non-infested area than in healthy animals from an infested area. The differences found in the chamois were indicative of the establishment of a humoral antibody response in the animals in contact with the disease. As the IgG levels were not significantly different between healthy and infested Spanish ibex from the same area, a different pattern of chronic infection with humoral response to the disease was suggested.

[Small-cell nonanaplastic bronchogenic carcinoma. The new stage I]

OBJECTIVE

To validate updated guidelines for stage I classification of patients with differentiated small-cell bronchogenic carcinoma.

METHODS

Seven hundred seventeen tumors of differentiated small-cell bronchogenic carcinoma were resected in our hospital and given a TNM classification of stage I based on guidelines recently issued by the Spanish Society of Pneumology and Chest Surgery (SEPAR). Survival was calculated using the Kaplan-Meier method and curves were compared with a log-rank test. The Cox proportional hazards model was used to analyze multiple variables.

RESULTS

One hundred forty-two cases were classified as stage IA and 575 as stage IB. Survival was significantly longer for stage IA than for stage IB (p = 0.0021). The prognosis was significantly better for stage IA patients who were asymptomatic (p = 0.0380) or who had tumors < or = 2 cm in diameter (p = 0.0431). In stage IB, histologic grade (p = 0.0104) and tumor diameter (p = 0.0002) significantly affected survival. A noteworthy finding was the 82% survival at five years in a group of 66 patients with a maximum tumor diameter of 3 cm classified as T2N0M0 due to invasion of the visceral pleura or to proximal involvement of a lobar bronchus at a site > 2 cm from the carina; that survival rate was not significantly different from survival for stage IA (p = 0.1573). Multivariate analysis showed that tumor diameter (p = 0.0272) was of prognostic importance in stage IA, while tumor diameter (p = 0.0005) and histologic grade (p = 0.0092) were relevant in stage IB.

CONCLUSION

The new staging guidelines for differentiated small-cell bronchogenic carcinoma are nearer to prognostic reality given that survival for stage IA patients is significantly longer than for stage IB patients. However, the method continues to have shortcomings in that it fails to achieve one of its main objectives, namely prognostic homogeneity for each subgroup, as indicated by problems related to variables of tumor extension such as diameter, involvement of the visceral pleura or bronchial location, apart from other factors that affect survival.

Information processing in large-scale cerebral networks: the causal connectivity approach

Today, cognitive functions are considered to be the offspring of the activity of large-scale networks of functionally interconnected cerebral regions. The interpretation of cerebral activation data provided by functional imaging has therefore recently moved to the search for the effective connectivity of activated regions, which aims at understanding the role of anatomical links in the activation propagation. Our assumption is that only causal connectivity can offer a real understanding of the links between brain and mind. Causal connectivity is based on the anatomical connection pattern, the information processing within cerebral regions and the causal influences that connected regions exert on each other. In our approach, the information processing within a region is implemented by a causal network of functional primitives, which are the interpretation of integrated biological properties. Our choice of a qualitative representation of information reflects the fact that cerebral activation data are only the approximate view, provided by imaging techniques, of the real cerebral activity. This explicit modeling approach allows the formulation and the simulation of functional and physiological assumptions about activation data. Two alternative models explaining results of the striate cortex activation described by Fox and Raichle (Fox PT, Raichle ME (1984) J. Neurophysiol 51:1109-1120; Fox PT, Raichle ME (1985) Ann Neurol 17:303-305) are provided as an example of our approach.

[The prognosis following surgical resection of small-cell nonanaplastic bronchogenic carcinoma according to the new staging guideline: an analysis of 1433 patients]

OBJECTIVE

To validate current guidelines for staging bronchogenic lung carcinoma.

METHODS

Between 1969 and 1996, small-cell non-anaplastic tumors of bronchogenic carcinoma classified by the recently proposed TNM guidelines of the Spanish Society of Pneumology and Chest Surgery (SEPAR) were resected from 1,433 patients. We used the Kaplan-Meier method to calculate survival and compared the curves using a log-rank test.

RESULTS

A stage IA classification was given to 142 patients and IB to 575. Thirty-seven cases were classified IIA and 336 were IIB. Of the latter, 177 were T2N1M0 and 159 were T3N0M0. Two hundred forty-eight patients were in stage IIIA, 54 T3N1M0, 23 T1N2M0, 120 T2N2M0 and 51 T3N2M0. Ninety-five stage IIIB patients were classified as follows: 37 T4N0M0, 35 T4N1M0, and 23 T4N2M0. Five-year survival for IA patients, at 75% was significantly better than the 60% rate for IB patients (p = 0.0021). Likewise, the prognosis for stage IIA, where five-year survival was 57%, was significantly better than for IIB at 39% (p = 0.0434). The prognosis for patients classified as T1NM0 was better than for those classified as T2N1M0, which was 38% (p = 0.0320). The survival of those classified as T3N0M0 (42%) was not significantly different from that of T1N1M0 (p = 0.1754) or T2N1M0 (p = 0.5360) patients. We found no significant difference between T1N1M0 and stage IB (p = 0.3847) patients. Among stage III patients, we observed no difference in survival between stage IIIA and IIIB (p = 0.1914). In stage IIIA, patients classified as T3N2M0 had a significantly lower rate of survival (p = 0.0399). The presence of mediastinal ganglia in stage IIIB was associated with a lower survival rate (p = 0.0328).

CONCLUSION

The new guidelines for staging non-small cell anaplastic lung carcinoma do not provide consistent prognoses for homogeneous groups of patients, at least not in certain categories.

[Reflex benign myoclonic epilepsy of childhood. Apropos of a new case]

INTRODUCTION

Recently a series of cases has been reported characterized by myoclonic crises similar to those occurring in benign myoclonic epilepsy of childhood. However, these crises only occurred after unexpected tactile or auditory stimuli. These clinical conditions represent a new epileptic syndrome, which is age-dependent and has been called benign myoclonic epilepsy of childhood.

CLINICAL CASE

We present the case of a 12 month old girl with myoclonic crises which occurred only after auditory or tactile stimuli. The myoclonia could be set off whilst awake or asleep. No other types of crises or neurological changes were seen. A brother of the patient had had febrile convulsions. The EEG recorded during the crises showed generalized brief spike-and-wave discharges at 3 cycles/second. The intercritical EEG was normal whilst awake, but during sleep showed brief generalized discharges. After treatment with valproate was started the crises became less frequent.

CONCLUSIONS

The case we describe is similar to those described by Ricci et al in 1995. We, therefore, consider it to fit the concept of reflex myoclonic epilepsy of childhood of benign character. We consider that this condition should be differentiated from other reflex epilepsies and epileptic syndromes with a predominance of myoclonia, including benign myoclonic epilepsy of childhood.

[Resection of bronchogenic carcinoma invading the diaphragm]

The prognosis for survival when small cell non-anaplastic bronchogenic carcinoma (SCN-ABC) invades the diaphragm has not been clearly established because the diagnosis is rare. We report a series of eight patients who underwent full resection of SCN-ABC with diaphragm invasion. One died during the postoperative period. Mean survival was eight months for the remaining seven and no patient lived five years. All died as a result of remote metastasis. Given these results, we question whether surgery is the most appropriate treatment for these patients.

ERP correlates of phoneme perception in speech and sound contexts

To address the question of the existence of a phonetic module for speech perception, event-related potentials were recorded using a 32 channel system in subjects performing a detection task where the target was the ambiguous, noise-like phoneme /f/ presented either among syllables (speech context) or among environmental sounds (non-speech context). Significant context effects were observed on the N2/P3 complex elicited by the target. In particular, a well localized N2b (250-280 ms) appeared at the left temporoparietal sites on the difference wave between contexts as the result of an enhanced negativity when the target was presented among non-speech stimuli. These findings suggest the involvement of the left temporoparietal region in autonomous, modular processes of speech perception.

Differences in anti-CREG antibody formation between transplanted and nontransplanted renal patients

BACKGROUND

The aim of this study was investigation of the HLA-I cross-reactive group (CREG)-specific antibodies (Abs) in sera from patients with a failed renal transplant and from nontransplanted patients.

METHODS

A total of 5292 sera from 570 patients awaiting kidney transplantation were screened for the presence of HLA-I CREG-specific Abs. Patients who had never received a transplant (group A), and those with a previous transplant and Abs either not related (group B) or related to donor specificities (group C) were studied. A further division was made for Abs directed against specificities either included in (intra-CREG) or not included in patients' HLA-CREG (extra-CREG).

RESULTS

Twelve of 24 (50%) Abs produced in response to mismatched donor HLA specificities after a failed graft were intra-CREG Abs, compared to 7 of 39 (18%) Abs that were not transplant-related.

CONCLUSIONS

Renal grafts showed a stronger immunogenicity than other sources of allosensitization. Our data also suggest that CREG matching may not be useful for renal allocation.

Urinary cotinine and exposure to parental smoking in a population of children with asthma

BACKGROUND

Studies of the effects of tobacco smoke often rely on reported exposure to cigarette smoke, a measure that is subject to bias. We describe here the relationship between parental smoking exposure as assessed by urinary cotinine excretion and lung function in children with asthma.

METHODS

We studied 90 children 4-14 years of age, who reported a confirmed diagnosis or symptoms of asthma. In each child, we assessed baseline pulmonary function (spirometry) and bronchial responsiveness to carbachol stimulation. Urinary cotinine was measured by HPLC with ultraviolet detection.

RESULTS

Urinary cotinine concentrations in the children were significantly correlated (P <0.001) with the number of cigarettes the parents, especially the mothers, smoked. Bronchial responsiveness to carbachol (but not spirometry test results) was correlated (P <0.03) with urinary cotinine in the children.

CONCLUSION

Passive smoke exposure increases the bronchial responsiveness to carbachol in asthmatic children.

Suramin treatment in hormone- and chemotherapy-refractory prostate cancer

OBJECTIVES

Suramin, a polysulfonated naphtylurea with anti-growth factor activity, was used in the treatment of metastatic, hormone- and chemotherapy-refractory prostate cancer. Recent studies have proved the effect of suramin on prostate cancer.

METHODS

Between March 1990 and January 1994, 27 patients with metastatic prostate cancer were enrolled in this study. Treatment regimen consisted of a loading phase, allowing patients to reach suramin serum levels between 180 and 250 microg/mL using a suramin dose of 1.4 g/m2 at 3-day intervals. Constant suramin serum levels were maintained by a 0.5 to 1-g/m2 dose every 7 to 10 days. Because previous studies showed suramin to have serious toxicity, compromised organ status was excluded by repeated examinations.

RESULTS

Six patients did not complete the suramin loading phase because of side effects and were removed from the study. With an average cumulative suramin dose of 14.2 g, 33% of the assessable patients (7 of 21) experienced a more than 50% reduction of prostate-specific antigen (PSA) and/or alkaline phosphatase (AP) serum levels. Mean survival in these suramin-responsive patients was 495 days. Two of these patients experienced a remarkable reduction of metastases in bone scan examinations. Another 48% of the patients (10 of 21) had essentially unchanged AP and PSA serum levels during suramin treatment, indicating stable disease. Mean survival of these patients was 341 days. In 4 patients undergoing suramin treatment, continuous clinical progression of the disease was observed (mean survival 79 days). Toxicity was less or comparable to prior reported studies; the most common side effects were polyneuropathy, allergic skin rash, and vortex keratopathy.

CONCLUSIONS

Suramin has limited, but significant, efficacy even in chemotherapy- and hormone-refractory prostate cancer, without serious toxicity.

[Polyneuropathy in patients with periodic leg movements during sleep]

INTRODUCTION

Periodic legs movements of sleep (PLMS) are rhythmic, standard and repetitive contractions of muscles of the extremities during the sleep. It is known that the patients with restless legs syndrome (RLS) have disorders during the sleep: increase in the latency of the sleep, increased number of arousal, etc.; most of them have also periodic movements of the legs during the sleep.

OBJECTIVE

The relationship of the periodic movements of the legs during the sleep with polyneuropathy is not clear. Some authors have found evidence of electrophysiological and pathological of signs of axonal mild polyneuropathy in patients with restless legs syndrome. In this work, we evaluated nine patients that were diagnosed of PLMS, to determine the prevalence of neuropathy in such sample.

METHOD

Polysomnography of nocturnal sleep of 7-8 hours was performed, including electromyographic recording of both anterior tibialis muscles; and electroneurographic study of peroneal, sural, ulnar and median nerves.

DISCUSSION

Just in none of the nine studied cases were obtained electrophysiological signs of neuropathy; though it has been able to demonstrate the existence of mild alteration of the peripheral nervous system, fundamentally of sensory character; nevertheless, C we think that it would have to be studied the existence of polyneuropathy in all the patients with PLMS in order to discard potentially tractable organic causes.

Method for simultaneous measurements of traces of heptadeuterated cholesterol and cholesterol by gas chromatography-mass spectrometry: application in humans

An assay was developed to quantify deuterated cholesterol (used as a tracer) and cholesterol using gas chromatography-mass spectrometry. Ergosterol and epicoprostanol were used as internal standards. Deuterated cholesterol was quantified by comparing its peak area to that of epicoprostanol and cholesterol to ergosterol. The mean absolute recovery in spiked serum was 99.96%; the precision was in the range 0.16-10.9% and accuracy 90.4-100%; the limit of detection in plasma was 3x10(-5) mmol l(-1). Using two internal standards, the method described herein seems particularly suitable for application in humans i.e., measuring traces of deuterated cholesterol (range: 0-6.26 x 10(-4) mmol l(-1)) along with natural cholesterol (range: 0.065-4.42 mmol l(-1)) in human plasma and lipid fractions postprandially.

Nasal granuloma caused by Scedosporium apiospermum in a dog

A 10-month-old male American Staffordshire terrier was presented to the Autonomous University of Barcelona Veterinary Teaching Hospital because of a 6-month history of a mucopurulent bilateral nasal discharge. The dog had not responded to antibiotics. A follow-up X ray revealed a mixed pattern of osteolysis and increased radiodensity confined to the nasal cavity. Histologic sections of the biopsy specimens revealed the presence of granules containing numerous septate hyphae that were hyaline to pale brown and smooth, one-celled, subspherical-to-elongate conidia that were hyaline to brownish green, and bacteria. Cultures yielded numerous colonies belonging to Scedosporium apiospermum. Susceptibility tests were performed on the isolated strain. The isolate was sensitive to ketoconazole, intermediate to clotrimazole, and resistant to amphotericin B, 5-fluorocytosine, fluconazole, and itraconazole. The dog was treated with oral ketoconazole. During the treatment a general improvement in the lesions was observed. To our knowledge, S. apiospermum has not been implicated previously as an etiologic agent of nasal disease in dogs. This report provides its first description as such.