Staphylococcal toxins: screening of burn wound isolates and evidence for alphahaemolysin production in the burn wound

Culture filtrates of Staphylococcus aureus strains isolated from burn patients were examined for cytotoxic activities. A large molecular weight cytotoxin (MW=253000 daltons) that exhibited cytotoxicity for human foreskin cells and haemolytic activity against human and rabbit erythrocytes was identified. The cytotoxic activity could be completely neutralized by antiserum formed against the cytotoxin. Further characterization of the molecule by isoelectric focusing revealed that the cytotoxin was composed of at least two toxic factors of smaller molecular weight. Both factors exhibited cytotoxicity to tissue-culture cells. however, one factor lysed rabbit but not human erythrocytes whereas the other factor had the opposite haemolytic pattern. The cytotoxicity of each factor was neutralized by the antiserum formed against the cytotoxin. A cytotoxic factor that exhibited haemolytic activity for rabbit erythrocytes, and that was neutralized by the cytotoxin antiserum, was identified in burn wound extracts of mice infected with Staph. aureus. On the basis of molecular weight and isoelectric focusing data, we conclude that the large molecular weight cytotoxin was composed of an aggregation of alpha-haemolysin and another presently unidentified toxic molecule, possibly delta-toxin. Alpha-haemolysin appears to be produced in vivo during experimental staphylococcal burn wound infection.     

Role of group II and group III metabotropic glutamate receptors in spinal cord injury.

Spinal cord injury (SCI) produces an increase in extracellular excitatory amino acid (EAA) concentrations that results in glutamate receptor-mediated excitotoxic events. An important class of these receptors is the metabotropic glutamate receptors (mGluRs). mGluRs can activate a number of intracellular pathways that increase neuronal excitability and modulate neurotransmission. Group I mGluRs are known to modulate EAA release and the development of chronic central pain (CCP) following SCI; however, the role of group II and III mGluRs remains unclear. To begin evaluating group II and III mGluRs in SCI, we administered the specific agonists for group II, APDC, or group III, L-AP4, by interspinal injection immediately following SCI. Contusion injury was produced at spinal segment T10 with a New York University impactor (12.5-mm drop, 10-g rod 2 mm in diameter) in 30 adult male Sprague-Dawley rats (175-200 g). Evoked and spontaneous behavioral measures of CCP, locomotor recovery, changes in mGluR expression, and amount of spared tissue were examined. Neither APDC nor L-AP4 affected locomotor recovery or the development of thermal hyperalgesia; however, L-AP4 and APDC attenuated changes in mechanical thresholds and changes in exploratory behavior indicative of CCP. APDC- and L-AP4-treated groups had higher expression levels of mGluR2/3 at the epicenter of injury on post contusion day 28; however, there was no difference in the amount of spared tissue between treatment groups. These results demonstrate that treatment with agonists to group II and III mGluRs following SCI affects mechanical responses, exploratory behavior, and mGluR2/3 expression without affecting the amount of tissue spared, suggesting that the level of mGluR expression after SCI may modulate nociceptive responses.     

Substrate inhibition of adenosine phosphorylation in adenosine deaminase deficiency and adenosine-mediated inhibition of PP-ribose-P dependent nucleotide synthesis in hypoxanthine phosphoribosyltransferase deficient erythrocytes

Summary The metabolism of adenosine and its effects on phosphoribosylpyrophosphate, PP-ribose-P, dependent nucleotide synthesis were studied using erythrocytes from patients with adenosine deaminase and hypoxanthine phosphoribosyltransferase deficiency as models. The phosphorylation of adenosine was progressively inhibited by concentrations of adenosine greater than 1 µmol L^–1 for control and ADA deficient erythrocytes. There was essentially no initial rate of phosphorylation at 30 µmol L^–1 adenosine. Adenosine, 1 µmol L^–1, also caused a 60% reduction in PP-ribose-P concentration in ADA deficient erythrocytes. For HPRT deficient erythrocytes in which ADA activity was blocked by coformycin, 10 µmol L^–1 inosine stimulated PP-ribose-P dependent nucleotide synthesis from adenine, whereas, 10 µmol L^–1 adenosine inhibited nucleotide synthesis. These observations suggest that adenosine phosphorylation and PP-ribose-P dependent nucleotide synthesis are inhibited under conditions in which adenosine accumulates, such as in hereditary or pharmacologically induced ADA deficiency.     

Effects of the putative dopamine autoreceptor antagonists (+)-AJ 76 and (+)-UH 232 on the discriminative stimulus properties of cocaine

Recent evidence suggests that the putative dopamine (DA) autoreceptor antagonists, (+)-AJ 76 and (+)-UH 232, share some neurochemical and behavioral effects with both psychostimulants and neuroleptics. The ability of (+)-AJ 76 and (+)-UH 232 to mimic or antagonize the stimulus effects of cocaine was investigated in rats trained to discriminate 5 mg/kg (N=8) or 10 mg/kg (N=8) of cocaine from saline in a two-lever, water-reinforced, drug discrimination task. In the cocaine (10 mg/kg) group, administration of (+)-AJ 76 (2.5–20 mg/kg) engendered only a partial substitution for cocaine (maximum 60% cocaine-lever responses). Given in combination with cocaine (10 mg/kg), (+)-AJ 76 (2.5–40 mg/kg) did not significantly attenuate the cocaine cue. A fixed dose of (+)-AJ 76 (2.5 or 10 mg/kg) plus various doses of cocaine (1.25–5 mg/kg) did not alter the cocaine dose-response curve. (+)-UH 232 (2–16 mg/kg) produced primarily saline-appropriate responding in rats trained to discriminate 5 mg/kg of cocaine and was unable to block the interoceptive cocaine state when given in combination with cocaine (5 mg/kg). (+)-UH 232 (2 or 8 mg/kg) also did not alter the cocaine dose-response curve. These results suggest that (+)-AJ 76 and (+)-UH 232 elicit only weak or no cocaine-like stimulus effects and, unlike neuroleptics, do not attenuate the cocaine cue.     

In vivo fluorescence spectroscopy and imaging of human skin tumours

The feasibility of using in vivo autofluorescence for the diagnosis of skin cancer was evaluated. In vivo fluorescence measurements were performed on healthy human volunteers, and patients with different types of benign and malignant skin tumours. Fluorescence spectra as well as fluorescence images were acquired. The excitation-emission matrix of normal skin (n=3) showed a broad peak at the shortest excitation wavelength (365 nm) and at 440 nm fluorescence wavelength, smoothly decreasing towards longer excitation and fluorescence wavelengths. Non-melanoma skin tumours (n=31) and control skin excited with 375 nm showed a broad fluorescence band from 400 to 700 nm, peaking around 436 nm. No significant differences in measurements between tumours and the corresponding control sites were found. A large spatial variation in the fluorescence intensity was observed both in the tumours and in the control sites. Standard deviations found ranged from 0.15 to 1.5 times the mean fluorescence. Fluorescence images, excited with 375 nm and taken with an image intensified CCD camera, on eight malignant melanomas and eight benign pigmented lesions did not indicate any fluorescence intensity distribution specific to the malignancy of the lesion. Neither the shape of the fluorescence spectra, nor the spatial distribution of the fluorescence intensity showed any signature specific to the histopathological nature of the lesions investigated. Optical diagnostics of skin tumours using the autofluorescence does not seem to be feasible at the present time.     

Primary Burkitt Lymphoma of the Chest Wall

IntroductionBurkitt lymphoma (BL) originating in the skin and soft tissue is very rare. To our knowledge, this case of primary sporadic BL presenting as an isolated chest wall mass arising from the soft tissue in an adult may be the first report.Case ReportA previously healthy 33-year-old Caucasian man presented with a 1-month history of a painful lump over the left breast that he initially noticed as a small “pimple-like” lesion in the area. After a week, the skin lesion became larger, erythematous, and painful. At a local hospital, he underwent an incision and drainage procedure for a presumed chest wall abscess. Several days after debridement, a similar lump recurred around the incised area, which rapidly grew in size. He also started experiencing fever and chills for which he was readmitted with a diagnosis of necrotizing chest wall infection. A second debridement with excisional biopsy of the chest wall revealed atypical lymphoid cells, prompting transfer to our institution. Upon transfer, a large, gaping, erythematous and indurated wound with indistinct, thickened borders and extensive edema and necrosis of subcutaneous tissue and musculature of almost the entire left chest wall was noted. No palpable peripheral lymphadenopathy or organomegaly were observed. He underwent minimal debridement and partial excision. The histopathology revealed atypical lymphocytes with prominent nucleoli, deeply basophilic cytoplasm, and abundant lipid vacuoles in a “starry-sky” pattern. The lymphoid population was CD-20 and CD-10 positive, negative for CD-5 and BCL-2, nearly 100% Ki-67 positive, and indeterminate for light chain restriction. Molecular cytogenetic analysis revealed fusion signals with IgH/Myc t(8;14) dual fusion probe, supporting the diagnosis of BL. Staging positron emission tomography (PET)/computed tomography (CT) scan showed a large subcutaneous defect of the left hemithorax involving the dermis, subcutaneous tissue, and musculature, measuring 19.3 × 13.9 × 31.0 cm, with maximal SUV of 9.8 and an average of 6.2. No additional involved sites were seen. The bone marrow biopsy showed minimal involvement by BL and abnormal hybridization pattern for IgH/Myc t(8;14) and Epstein-Barr virus, while the peripheral blood and cerebrospinal fluid showed no involvement. HIV and hepatitis serologies were negative. Three days after surgery, chemotherapy with granulocyte colony-stimulating factor (G-CSF) support was initiated for high-risk disease. He received CODOX-M (intravenous cyclophosphamide, doxorubicin, vincristine, methotrexate; intrathecal cytarabine, methotrexate) as cycle 1 followed by IVAC (intravenous ifosfamide, etoposide, cytarabine; intrathecal methotrexate) with rituximab as cycle 2. He developed tumor lysis without end-organ damage. However, a few days after completion of cycle 2, he developed neutropenic fever and pneumonia, and died in septic shock.DiscussionPrimary chest wall tumors are uncommon. Approximately 50% are malignant, and chest wall lymphoma accounts for < 2%, with extranodal diffuse large B-cell lymphoma being the most common. Primary skin and soft tissue involvement of the chest wall in the absence of detectable lymphadenopathy and visceral disease in an adult by BL has not yet been reported. While there are isolated reports of skin and soft tissue involvement, they were in the setting of immunodeficiency state and were felt to be the result of either iatrogenic tumor seeding after nodal biopsies or local tumor invasion as a manifestation of recurrent disease. This patient's clinical presentation began with the development of an isolated rapidly enlarging chest wall mass that progressed despite surgical debridements.ConclusionThis case illustrates a primary sporadic BL originating in skin and soft tissue in an adult. Whether this case represents a BL that began in the skin and soft tissue and spread to the bone marrow, or began in the bone marrow and spread to the chest wall cannot be determined. The role of tumor debulking procedure is uncertain, although aggressive chemoimmunotherapy with central nervous system (CNS) prophylaxis is warranted as with other BL presentations.