The development of Lewisite vapour induced lesions in the domestic, white pig

Studies performed in the past in our laboratory have detailed the development of sulphur mustard lesions in the domestic, white pig using small glass chambers to achieve saturated vapour exposure under occluded conditions. We have now used this experimental model to produce cutaneous lesions for detailed histopathological studies following challenge with lewisite. Histological examination of resulting lesions have revealed that although the overall pattern of lesion development is similar to that seen following mustard challenge, the time-course of cellular events is very much compressed. The epidermis showed focal basal cell vacuolation with associated acute inflammation as early as one hour postexposure. Coagulative necrosis of the epidermis and papillary dermis was complete by 24 hours and followed the appearance of multiple coalescent blisters between six and 12 hours post-exposure. At 48 hours, the lesions were full thickness burns with necrosis extending into the deep subcutaneous connective and adipose tissues. The study of lesions beyond 24 hours revealed early epithelial regeneration at the wound edge. The overall spontaneous healing rate of these biologically severe lesions was significantly faster than comparable sulphur mustard injuries and probably reflected a lack of alkylation of DNA and RNA.

The use of laser Doppler imaging as an aid in clinical management decision making in the treatment of vesicant burns

Vesicants are a group of chemicals recognised, under the terms of the Chemical Weapons Convention, as potential chemical warfare agents whose prime effect on the skin is to cause burns and blistering. Experience of the clinical management of these injuries is not readily available and therefore an accurate assessment of the severity of the lesion and extent of tissue involvement is an important factor when determining the subsequent clinical management strategy for such lesions. This study was performed to assess the use of laser Doppler imaging (LDI) as a noninvasive means of assessing wound microvascular perfusion following challenge with the vesicant agents (sulphur mustard or lewisite) by comparing the images obtained with histopathological analysis of the lesion. Large white pigs were challenged with sulphur mustard (1.91 mg cm(-2)) or lewisite (0.3 mg.cm(-2)) vapour for periods of up to 6 h At intervals of between 1 h and 7 days following vesicant challenge, LDI images were acquired and samples for routine histopathology were taken. The results from this study suggest that LDI was: (i) a simple, reproducible and noninvasive means of assessing changes in tissue perfusion, and hence tissue viability, in developing and healing vesicant burns; (ii) the LDI images correlates well with histopathological assessment of the resulting lesions and the technique was sufficiently sensitive enough to discriminate between skin lesions of different aetiology. These attributes suggest that LDI would be a useful investigative tool that could aid clinical management decision making in the early treatment of vesicant agent-induced skin burns.

Isolation of reptilian calicivirus Crotalus type 1 from feral pinnipeds

Ten virus isolates were obtained from three species of marine mammals sampled on San Miguel Island (California, USA) and 1,200 km north on Rogue Reef (Oregon, USA) during tagging operations in 1986-87. Seven of these 10 were derived from 30 sampled Steller sea lion (Eumetopias jubatus pups, while two of 10 were isolated from one of 19 sampled California sea lion (Zalophus californianus californianus pups, and the remaining isolate was derived from 30 sampled northern fur seal (Callorhinus ursinus) pups. All 10 isolates were identified as belonging to a single serotype, reptilian calicivirus Crotalus type 1 (RCV Cro-1), previously isolated from both healthy and diseased snakes and frogs in a California zoologic collection. The marine samples also showed that nine of 30 Steller sea lion pups, one of 19 California sea lion pups and zero of 30 fur seal pups were producing type specific neutralizing antibodies to RCV Cro-1. This represents the first reported instance of the isolation from marine sources of calicivirus originally isolated from a terrestrial species.

Gastroesophageal reflux and Nissen fundoplication following percutaneous endoscopic gastrostomy in children

BACKGROUND

Abnormal gastroesophageal reflux after percutaneous endoscopic gastrostomy is a serious problem in neurologically impaired children. Protective fundoplication has been advocated. Whether esophageal pH monitoring before percutaneous endoscopic gastrostomy will predict later problems with gastroesophageal reflux is unclear.

METHODS

Eighty-five mostly neurologically impaired pediatric patients who underwent percutaneous endoscopic gastrostomy were studied retrospectively regarding complications, success of nutritional rehabilitation, and the incidence of pathologic gastroesophageal reflux. Follow-up period was 1 to 4 years. Twenty-four-hour esophageal pH monitoring was performed in 46 patients before percutaneous endoscopic gastrostomy.

RESULTS

There were no deaths. Two major complications occurred that required surgical intervention, and 14 minor complications occurred related to the procedure. Z-scores for weight increased significantly after percutaneous endoscopic gastrostomy. pH probe results were normal in 22 patients (group 1). Five required medical treatment for gastroesophageal reflux after percutaneous endoscopic gastrostomy, but only 1 (5%) later required Nissen fundoplication. pH probe results were abnormal in 24 patients (group 2). Nineteen required medical therapy for gastroesophageal reflux, and 7 (29%) later needed fundoplication (p < 0.05, incidence of fundoplication group 1 vs. group 2). Improvement in Z-scores was similar in patients requiring and not requiring fundoplication.

CONCLUSIONS

Percutaneous endoscopic gastrostomy is a safe and effective technique for long-term nutritional support in children. Abnormal gastroesophageal reflux is common. Normal findings in an esophageal pH study before percutaneous endoscopic gastrostomy may be predictive of a favorable outcome with respect to gastroesophageal reflux. This is in contrast to patients with abnormal results in pH studies before percutaneous endoscopic gastrostomy of whom a relatively large percentage may later require fundoplication. Improved nutritional status after percutaneous endoscopic gastrostomy does not appear to have an impact on the severity of gastroesophageal reflux.

Bacterial lipopolysaccharides induce peripheral nerve disturbances in rats that mimic human immune-mediated polyneuropathies

A single injection of Escherichia coli lipopolysaccharide (LPS; i.v. and i.p.) reliably induced peripheral nerve disturbances in male Australian albino Wistar (AaW) rats. Signs developed 6 to 24 h after LPS inoculation and persisted only transiently. Most AaW rats had variable degrees of bilateral hind limb impairment, and rarely had forelimb, tail, or central impairment. Signs included gait abnormalities, proprioceptive loss, and to a lesser extent hind limb weakness and sensory deficits. Signs were more severe in male than female AaW rats and were induced in a number of genetically related rat strains (e.g., AaW and outbred Wistar and inbred Lewis rats, but not Sprague Dawley or inbred Fischer 344 rats). Development and severity of these signs were found not be related to animal body weight, but were dependent on LPS dose. Signs were not associated with LPS-induced alterations in pain perception, or occurrence of spontaneous pain, as indexed by tail-flick and hot-plate tests. Taken together, these data indicate that LPS induced transient peripheral nerve disturbances in rats, the severity of which was influenced by genetic, sex-related, and dose-related factors.

Ultrastructure of rat lung following inhalation of ricin aerosol

Ricin is one of a group of structurally related plant lectins and is extracted from the seeds of the Castor Oil plant, Ricinus communis. Groups of rats were exposed to ricin aerosol by inhalation, total LCt1-11.21 mg.min.m-3 (an approximate LCt30 exposure) and examined, using transmission electron microscopy, at intervals up to 48 h after exposure. The first signs of change in ultrastructure were seen at between 6 and 12 h post exposure in alveolar macrophages and took the form of apoptotic changes primarily in the nucleus. These included heterochromatin condensation at the nuclear periphery and crenulation of the nuclear membrane. There then followed a sequence of changes in the cells of the alveolar wall and blood/air barrier culminating in intra-alveolar oedema at 12 and 15 h after exposure. Damage was first observed in the capillary endothelium and type I epithelial cell changes were evident from 12 h post exposure onward. These changes appeared to be necrotic rather than apoptotic in nature and suggest that mechanisms other than a direct effect of ricin may be involved. Associated with these changes were mixed inflammatory cell infiltrates in the interstitium, isolated type II pneumocyte necrosis and evidence of microvascular microthrombosis. By 48 h after exposure, the intra-alveolar oedema appeared less marked with prominent hyperplasia of type II pneumocytes. The identification that apoptosis of alveolar macrophages plays a significant part in the mechanism of toxicity following exposure to ricin raises the possibility of developing new therapeutic strategies against poisoning by ricin.

Histopathological changes in Yucatan minipig skin following challenge with sulphur mustard. A sequential study of the first 24 hours following challenge

Sulphur mustard (HD) or "mustard gas' is a potent vesicant chemical warfare agent whose biological effects in man have been well documented. The histopathological features of the developing cutaneous HD lesion in female Yucatan minipigs up to 24 hours post exposure are reported. Following challenge with HD vapour at a concentration of 12.0 mumol/cm2 a sequence of ultrastructural changes to keratinocytes occurred which were initially seen in the stratum basale. Condensation of nuclear heterochromatin and loss of euchromatin was accompanied by cytoplasmic swelling and culminated in focal epidermal necrosis which was evident at 24 h after the challenge. The melanocyte appeared to be the cell type most sensitive to HD challenge with a loss of cytoplasmic electron density in areas of the cytoplasm immediately surrounding the melanosomes, chromatin condensation, nuclear membrane blebbing with mitochondrial and generalized cytoplasmic swelling. Isolated complete cell necrosis and disruption were noted as early as 2 h following the challenge with generalized necrosis being seen from 12 h onwards. From 12 h onwards, areas of basement membrane degeneration were also observed. These appeared similar in ultrastructure to that observed in other animal model systems but did not progress to the large blisters so typical of the human lesion. Damage to the upper dermis took the form of an inflammatory response typified by vascular endothelial swelling and vacuolation, dermal oedema and inflammatory cell (mainly neutrophil) infiltration. There was some evidence of transitory epidermal damage outside the prescribed wound area. This finding may be of clinical importance when surgical treatments are being considered.

Protein losing enteropathy as the initial manifestation of childhood systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a multisystem organ disease, and involvement of the gastrointestinal system is relatively rare. We describe a 13-year-old girl who presented initially with abdominal pain, diarrhea, edema, and hypoalbuminemia. She was diagnosed with protein losing enteropathy (PLE) based on the significant increase of alpha 1-antitrypsin clearance in the stool. Two weeks after admission she developed clinical and serological findings that fulfilled the ACR criteria for SLE. Over 22 cases of lupus associated PLE have now been reported, but only 3 in children. Children with PLE should be evaluated for SLE. In addition, PLE should be suspected as a possible cause of unexplained edema and/or hypoalbuminemia in SLE.

Antagonists of phosphatidylinositol 3-kinase block activation of several novel protein kinases in neutrophils

Several novel protein kinases are known to be rapidly activated in neutrophils stimulated with the chemoattractant fMet-Leu-Phe (fMLP). These kinases include a histone H4 protein kinase and several renaturable kinases with molecular masses of about 69, 63, 49, and 40 kDa. The renaturable kinases can catalyze the phosphorylation of a peptide that corresponds to residues 297-331 of the 47-kDa subunit of the NADPH-oxidase system (p47-phox). Previous studies have indicated that the activation of all of these protein kinases involves an uncharacterized stimulatory pathway and/or novel second messenger. The studies reported herein were undertaken to determine if phosphatidylinositol 3-kinase (PI3-K) is a component of this pathway. We report that certain chromosome derivatives (e.g. 2-(4-morpholinyl)-8-phenylchromone (LY294002)) and wortmannin, which inhibit PI3-K by distinct mechanisms, blocked activation of all of these novel kinases. These antagonists also inhibited the phosphorylation of p47-phox (about 50%) and O2.- release (about 80%) in cells stimulated with fMLP, but not with 4 beta-phorbol 12-myristate 13-acetate. A strong correlation exists between the amounts of these antagonists required to produce 50% inhibition of PI3-K in vitro and O2.- release in vivo. In contrast, a single atom substitution of LY294002 produced a compound (LY303511) that did not inhibit PI3-K. Compound LY303511 did not appreciably inhibit the activation of the novel protein kinases or O2.- generation. These data strongly suggest that PI3-K is involved in the activation of several novel protein kinases in neutrophils, one or more of which may be involved in O2.- release.

Investigation of neutrophil signal transduction using a specific inhibitor of phosphatidylinositol 3-kinase

Neutrophils contain a multicomponent NADPH oxidase system that is involved in the production of microbicidal oxidants. Stimulation of human neutrophils with the peptide FMLP activates this respiratory burst enzyme to produce superoxide and also has been shown to result in activation of phosphatidylinositol (Ptdlns) 3-kinase. Treatment of human neutrophils with 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one (LY294002), a potent and specific inhibitor of Ptdlns 3-kinase, resulted in complete inhibition of Ptdlns 3-kinase activity as well as in inhibition of superoxide production in FMLP-treated neutrophils in suspension; FMLP-stimulated oxidant production in adherent cells was also abolished. Treatment of human neutrophils with PMA resulted in production of superoxide without activation of Ptdlns 3-kinase; LY294002 did not block superoxide production in neutrophils exposed to PMA. In addition, LY294002 did not inhibit cellfree NADPH oxidase activation, CD11b-dependent adhesion, actin polymerization in response to FMLP, or FMLP-induced calcium flux. These results suggest that the signal transduction pathway of the FMLP-receptor involves activation of Ptdlns 3-kinase, which is required for subsequent superoxide production induced by the chemotactic peptide. Furthermore, Ptdlns 3-kinase may be located directly upstream of protein kinase C or other protein kinases, which in turn activate the NADPH oxidase system.

Investigation of neutrophil signal transduction using a specific inhibitor of phosphatidylinositol 3-kinase

Neutrophils contain a multicomponent NADPH oxidase system that is involved in the production of microbicidal oxidants. Stimulation of human neutrophils with the peptide FMLP activates this respiratory burst enzyme to produce superoxide and also has been shown to result in activation of phosphatidylinositol (Ptdlns) 3-kinase. Treatment of human neutrophils with 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one (LY294002), a potent and specific inhibitor of Ptdlns 3-kinase, resulted in complete inhibition of Ptdlns 3-kinase activity as well as in inhibition of superoxide production in FMLP-treated neutrophils in suspension; FMLP-stimulated oxidant production in adherent cells was also abolished. Treatment of human neutrophils with PMA resulted in production of superoxide without activation of Ptdlns 3-kinase; LY294002 did not block superoxide production in neutrophils exposed to PMA. In addition, LY294002 did not inhibit cellfree NADPH oxidase activation, CD11b-dependent adhesion, actin polymerization in response to FMLP, or FMLP-induced calcium flux. These results suggest that the signal transduction pathway of the FMLP-receptor involves activation of Ptdlns 3-kinase, which is required for subsequent superoxide production induced by the chemotactic peptide. Furthermore, Ptdlns 3-kinase may be located directly upstream of protein kinase C or other protein kinases, which in turn activate the NADPH oxidase system.

Median nerve compression within the humeral head of pronator teres

We describe a case of the pronator syndrome caused by compression of the median nerve by a fibrous band as the nerve passed through the humeral head of origin of pronator teres. This rare anatomical arrangement resulted in displacement of the median nerve to the anterior aspect of the medial humeral epicondyle and, as far as we are aware, has not previously been described as a site of compression neuropathy.

Dipyridamole directly inhibits vascular smooth muscle cell proliferation in vitro and in vivo: implications in the treatment of restenosis after angioplasty

OBJECTIVES

The effect of dipyridamole on smooth muscle cell proliferation and prevention of intimal thickening after arterial injury was investigated.

BACKGROUND

In addition to antiplatelet activity, dipyridamole also inhibits cell proliferation. We examined whether the antiproliferative action of dipyridamole on smooth muscle cells, as demonstrated here, has a direct effect on intimal thickening after vascular injury.

METHODS

Cell proliferation was determined by measuring deoxyribonucleic acid (DNA) synthesis and by cell counting. The in vivo effect of locally delivered dipyridamole was determined in a rabbit model with carotid or femoral artery injury.

RESULTS

Dipyridamole produced a dose-dependent inhibition of smooth muscle cell proliferation, producing 50% inhibition at 7 micrograms/ml. Structural analogues SH-869 and mopamidol were 10 to 100 times less effective than dipyridamole, suggesting that cell growth inhibition may be unrelated to the antiplatelet activity of dipyridamole. Inhibition of cell proliferation by dipyridamole was attenuated by increasing the serum concentration in the culture medium. Bypassing serum by local delivery of dipyridamole at the periadventitial site produced 63% inhibition (p < 0.05) of cell replication in balloon-injured arteries. Locally delivered dipyridamole also inhibited intimal thickening (20%, p < 0.05) after balloon injury.

CONCLUSIONS

Dipyridamole inhibited smooth muscle cell proliferation in vitro. This activity was attenuated by serum proteins. Locally delivered dipyridamole inhibited cell replication in arteries and intimal thickening after balloon injury. These results suggest that although systemic treatment with dipyridamole may not be efficacious because of inadequate serum levels, its antiproliferative action on smooth muscle cells may reduce restenosis when the drug is delivered locally after coronary angioplasty.

A specific inhibitor of phosphatidylinositol 3-kinase, 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one (LY294002)

Phosphatidylinositol (PtdIns) 3-kinase is an enzyme implicated in growth factor signal transduction by associating with receptor and nonreceptor tyrosine kinases, including the platelet-derived growth factor receptor. Inhibitors of PtdIns 3-kinase could potentially give a better understanding of the function and regulatory mechanisms of the enzyme. Quercetin, a naturally occurring bioflavinoid, was previously shown to inhibit PtdIns 3-kinase with an IC50 of 1.3 microgram/ml (3.8 microM); inhibition appeared to be directed at the ATP-binding site of the kinase. Analogs of quercetin were investigated as PtdIns 3-kinase inhibitors, with the most potent ones exhibiting IC50 values in the range of 1.7-8.4 micrograms/ml. In contrast, genistein, a potent tyrosine kinase inhibitor of the isoflavone class, did not inhibit PtdIns 3-kinase significantly (IC50 > 30 micrograms/ml). Since quercetin has also been shown to inhibit other PtdIns and protein kinases, other chromones were evaluated as inhibitors of PtdIns 3-kinase without affecting PtdIns 4-kinase or selected protein kinases. One such compound, 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one (also known as 2-(4-morpholinyl)-8-phenylchromone, LY294002), completely and specifically abolished PtdIns 3-kinase activity (IC50 = 0.43 microgram/ml; 1.40 microM) but did not inhibit PtdIns 4-kinase or tested protein and lipid kinases. Analogs of LY294002 demonstrated a very selective structure-activity relationship, with slight changes in structure causing marked decreases in inhibition. LY294002 was shown to completely abolish PtdIns 3-kinase activity in fMet-Leu-Phe-stimulated human neutrophils, as well as inhibit proliferation of smooth muscle cells in cultured rabbit aortic segments. Since PtdIns 3-kinase appears to be centrally involved with growth factor signal transduction, the development of specific inhibitors against the kinase may be beneficial in the treatment of proliferative diseases as well as in elucidating the biological role of the kinase in cellular proliferation and growth factor response.

The ultrastructure of rat lung following acute primary blast injury

While a number of workers have described the effects of blast waves upon the lung at both the macroscopic and light microscopic level, studies involving the use of the electron microscope have not been reported. In the experiments reported here the ultrastructural changes seen in lungs from rats exposed to a blast wave impacting on the right side of the chest are described. Considerable damage to the right lower lobe was observed which took the form of tearing of the inter-alveolar septa with capillary rupture and intra-alveolar haemorrhage. Changes to the alveolar epithelium and type II pneumocytes were also noted. Lesions were also identified in the left lung; these included intra-alveolar oedema with a minimal amount of interstitial oedema together with increased pinocytosis and isolated rupture of the alveolar epithelium. 'Ballooning' of the endothelium into the lumen of the capillary was also observed. There was an indication that lesions noted in the left lung at the electron microscopic level may be progressive in the first 24 hours following injury.

Righting Scientific Writing: Focus on your main message!

This paper is about how to prepare research papers that are easier to write and easier to read. It draws on what we have learnt from running workshops for scientists about how to publish more readable papers. The key thing is to distil the most important point that needs to be made in a paper and then Structure the paper around that point so that readers cannot miss it. Mind-mapping and a clear understanding of what individual readers need to know are important tools to help distil a main message. Conversely, the traditional structure in which a paper builds to a knockout punch at the end and the traditional impersonal styles of written expression are he two most serious obstacles to the effective use of the main message strategy. Mastering the main message strategy is the key to writing papers that are easier to understand, and also easier to write.

The use of nitrogen, phosphorus and lime to limit the competitive ability of Aristida armata in the establishment phase

The de Wit replacement series methodology was used to see if applying phosphorus, nitrogen and lime to the sandy red earth soils of mulga grazing lands can give a competitive advantage to the desirable species Cenchrus ciliaris C.V. U.S.A., Digitaria ammophila, and Thyridolepis mitchelliana over the less desirable Aristida armata. In monoculture, all species responded strongly to added nutrients, especially phosphorus. In mixtures, the preferred grasses responded even more strongly to nutrients, whereas A. armata responsed proportionally less. C. ciliaris, D. ammophila, and T. mitchelliana suppressed the growth of A. amnata in all but three situations: without added nutrients, A. armata was equally competitive with C. ciliaris; when P was added without lime, A. armata suppressed C. ciliaris; if P was added without N, A. armata suppressed T. mitchelliana. Adding either or both nitrogen or phosphorus usually increased the relative crowding coefficients, indicating that the degree of suppression of Aristida was increased by adding nutrients. Thus, C. ciliaris, D. ammophila, and T. mitchelliana appear to be equally competitive with or more competitive than A. armata if the soil is not fertilized and adding nutrients generally enhances this competitiveness. In all cases, except for A. armata/C ciliaris mixtures in soils low in phosphorus, the plants appeared to be competing for the same resource. The study demonstrated that A. armata is not a highly competitive species per se under controlled conditions and was generally suppressed by the preferred grasses, especially when nutrients were added.

The effects of ileocystoplasty on the development of renal failure in a rat model 5/6 nephrectomy

We examined the effects of ileocystoplasty on renal function and bone mineral content in 160 juvenile male Wistar-Furth rats with and without renal insufficiency induced by 5/6 nephrectomy. At intervals up to 20 weeks blood, bone and kidney samples were obtained with the animals under anesthesia and then they were sacrificed. Serum parameters of renal function and calcium metabolism were measured. Samples of bone were analyzed for calcium, magnesium and phosphorus content. At 20 weeks after 5/6 nephrectomy renal function was decreased by approximately half. The decrease in renal function and the changes in renal histology were identical in animals with and without ileocystoplasty. Bone mineral content in the animals with renal insufficiency with or without ileocystoplasty was not different from sham operated animals or from animals with an ileocystoplasty and normal renal function. These studies demonstrate that ileocystoplasty per se does not hasten the progression to renal failure or produce bone demineralization in rats having moderate renal insufficiency.

The inhibition of phosphatidylinositol 3-kinase by quercetin and analogs

Phosphatidylinositol (PtdIns) 3-kinase is an enzyme involved in cellular responses to growth factors. Quercetin (2-(3,4-dihydroxyphenyl)-3,5,7-trihydroxy-4H-1-benzopyrano-4-one), a naturally occuring bioflavinoid, was found to inhibit PtdIns 3-kinase with an IC50 of 1.3 micrograms/ml (3.8 microM); inhibition appears to be directed towards the ATP binding site of the kinase. Analogs of quercetin were also investigated as PtdIns 3-kinase inhibitors, with the most potent compounds exhibiting IC50's in the range of 1.7-8.4 micrograms/ml (5-19 microM). In contrast, genistein, a potent tyrosine kinase inhibitor of the isoflavone class, did not inhibit PtdIns 3-kinase significantly (IC50 greater than 30 micrograms/ml). These findings suggest that flavinoids may serve as potent inhibitors of PtdIns 3-kinase. Furthermore, the enzyme is much more sensitive to substituents at the 3-position of the flavinoid ring than are other protein and PtdIns kinases, suggesting that specific inhibitors of PtdIns 3-kinase can be developed to explore the biological role of the enzyme in cellular proliferation and growth factor response.

Electron microscopy of rat lung following a single acute exposure to perfluoroisobutylene (PFIB). A sequential study of the first 24 hours following exposure

The histopathology of rat lung has been studied after an acute exposure to perfluoroisobutylene (PFIB) at a concentration of 638 mg/m3 (78 p.p.m.) for 1.5 min giving a Ct = 957 mg min/m3 for the first 24 h following exposure. Within 5 min of exposure changes to the bronchioles and peribronchial alveoli were observed which took the form of alterations to cilial structure, increased pinocytosis and electron lucency, with occasional vesicle formation of type I alveolar epithelial cells. Intercellular leakage with minimal fluid accumulation in the alveolar spaces was also seen. The very rapid action of PFIB strongly suggests a direct action by the compound. There then followed the gradual development of pulmonary oedema which was visible histologically 2-3 h post exposure with deaths occurring from 7 h onwards. Animals sacrificed at 24 h post exposure showed evidence of widespread pulmonary oedema and alveolar interstitial infiltration by lympho-mononuclear cells and macrophages.

Effects of experimental sarin intoxication on the morphology of the mouse diaphragm: a light and electron microscopical study

A sublethal dose of sarin (GB, isopropyl methylphosphonofluoridate) was administered to mice. The animals were killed up to 28 days after dosing. Following excision, diaphragms were divided into two halves and used for ultrastructural examination and light microscopy. Planar sections of diaphragm showed muscle fibre degeneration and predominantly mononuclear infiltration, notably at 24 h. Semithin toluidine blue-stained sections and ultrastructural studies demonstrated hypercontraction with gross disruption of sarcomeres including loss of Z and A bands, which appeared to be associated with neuromuscular junctions. All changes were rapidly regressing by 7 days.