Novel role for a bacterial nucleoid protein in translation of mRNAs with suboptimal ribosome-binding sites

In Escherichia coli, the major nucleoid protein H-NS limits transcription by acting as a repressor or transcriptional silencer, presumably by its ability to close the looped chromosome domains in the nucleoid through DNA-protein-DNA bridging. Here, we demonstrate the direct involvement of H-NS as a positive factor stimulating translation of the malT mRNA. In vitro studies showed that H-NS facilitates a repositioning of the 30S preinitiation complex on the malT mRNA. H-NS stimulation of translation depended on the AU-rich -35 to -40 region of the mRNA. Several additional examples were found demonstrating a novel function for H-NS in translation of genes with suboptimal ribosome-binding sequences.

Functional analysis of a lipid galactosyltransferase synthesizing the major envelope lipid in the Lyme disease spirochete Borrelia burgdorferi

One of the major lipids in the membranes of Borrelia burgdorferi is monogalactosyl diacylglycerol (MGalDAG), a glycolipid recently shown to carry antigenic potency. Herein, it is shown that the gene mgs (TIGR designation bb0454) of B. burgdorferi encodes for the protein bbMGS that, when expressed in Escherichia coli, catalyzes the glycosylation of 1,2-diacylglycerol with specificity for the donor substrate UDP-Gal yielding MGalDAG. Related lipid enzymes were found in many Gram-positive bacteria. The presence of this galactosyltransferase activity and synthesis of a cholesteryl galactoside by another enzyme were verified in B. burgdorferi cell extract. Besides MGalDAG, phosphatidylcholine, phosphatidylglycerol, and cholesterol were also found as major lipids in the cell envelope. The high isoelectric point of bbMGS and clustered basic residues in its amino acid sequence suggest that the enzyme interacts with acidic lipids in the plasma membrane, in agreement with strong enzymatic activation of bbMGS by phosphatidylglycerol. The membrane packing and immunological properties of MGalDAG are likely to be of great importance in vivo.

Distribution of intermediate filaments and actin microfilaments in parotid autoimmune sialoadenitis of Sjögren syndrome

In order to study the importance of myoepithelial cells in the formation of parotid epi-myoepithelial islands of the autoimmune sialoadenitis in Sjögren's syndrome, the distribution of cytoskeletal elements has been investigated by electron and immunofluorescence microscopy. Antibodies to intermediate filament proteins--prekeratins, desmin and vimentin--were used as well as a 'DNase I/anti-DNase I' immunohistochemical procedure to detect actin microfilaments for characterization of myoepithelial cells compared to the other types of parotid epithelial cells. Two types of prekeratin antibodies were raised. One of these reacted preferentially with myoepithelial cells. The same type of antiserum also showed a bright fluorescence in cells located peripherally in the epi-myoepithelial islands. These island cells, however, exhibited only a very low actin microfilament content and were thus not ordinary myoepithelial cells. The other type of prekeratin antibodies reacted with all types of parotid epithelia, except acinar secretory epithelium. They also stained all island epithelial cells, but the reactivity was less in cell regions with pronounced lymphocyte infiltration. The heterogeneity between the island epithelial cells, immunohistochemically as well as ultrastructurally, indicates different stages of island formation. Interepithelial lymphocytes showed less vimentin and actin filament content in comparison with lymphoid cells outside the islands. Conclusively, typical epi-myoepithelial islands are composed of metaplastic epithelial cells of intercalated duct origin and invaded lymphoid cells, and ordinary myoepithelial cells are lacking.

The etiological agent of Lyme disease, Borrelia burgdorferi, appears to contain only a few small RNA molecules

Small regulatory RNAs (sRNAs) have recently been shown to be the main controllers of several regulatory pathways. The function of sRNAs depends in many cases on the RNA-binding protein Hfq, especially for sRNAs with an antisense function. In this study, the genome of Borrelia burgdorferi was subjected to different searches for sRNAs, including direct homology and comparative genomics searches and ortholog- and annotation-based search strategies. Two new sRNAs were found, one of which showed complementarity to the rpoS region, which it possibly controls by an antisense mechanism. The role of the other sRNA is unknown, although observed complementarities against particular mRNA sequences suggest an antisense mechanism. We suggest that the low level of sRNAs observed in B. burgdorferi is at least partly due to the presumed lack of both functional Hfq protein and RNase E activity.

Pleiotropic effects of inactivating a carboxyl-terminal protease, CtpA, in Borrelia burgdorferi

A gene encoding a putative carboxyl-terminal protease (CtpA), an unusual type of protease, is present in the Borrelia burgdorferi B31 genome. The B. burgdorferi CtpA amino acid sequence exhibits similarities to the sequences of the CtpA enzymes of the cyanobacterium Synechocystis sp. strain PCC 6803 and higher plants and also exhibits similarities to the sequences of putative CtpA proteins in other bacterial species. Here, we studied the effect of ctpA gene inactivation on the B. burgdorferi protein expression profile. Total B. burgdorferi proteins were separated by two-dimensional gel electrophoresis, and the results revealed that six proteins of the wild type were not detected in the ctpA mutant and that nine proteins observed in the ctpA mutant were undetectable in the wild type. Immunoblot analysis showed that the integral outer membrane protein P13 was larger and had a more acidic pI in the ctpA mutant, which is consistent with the theoretical change in pI for P13 not processed at the carboxyl terminus. Matrix-assisted laser desorption ionization-time of flight data indicated that in addition to P13, the BB0323 protein may serve as a substrate for carboxyl-terminal processing by CtpA. Complementation analysis of the ctpA mutant provided strong evidence that the observed effect on proteins depended on inactivation of the ctpA gene alone. We show that CtpA in B. burgdorferi is involved in the processing of proteins such as P13 and BB0323 and that inactivation of ctpA has a pleiotropic effect on borrelial protein synthesis. To our knowledge, this is the first analysis of both a CtpA protease and different substrate proteins in a pathogenic bacterium.

Elimination of channel-forming activity by insertional inactivation of the p13 gene in Borrelia burgdorferi

P13 is a chromosomally encoded 13-kDa integral outer membrane protein of the Lyme disease agent, Borrelia burgdorferi. The aim of this study was to investigate the function of the P13 protein. Here, we inactivated the p13 gene by targeted mutagenesis and investigated the porin activities of outer membrane proteins by using lipid bilayer experiments. Channel-forming activity was lost in the p13 mutant compared to wild-type B. burgdorferi, indicating that P13 may function as a porin. We purified native P13 to homogeneity by fast performance liquid chromatography and demonstrated that pure P13 has channel-forming activity with a single-channel conductance in 1 M KCl of 3.5 nS, the same as the porin activity that was lost in the p13 mutant. Further characterization of the channel formed by P13 suggested that it is cation selective and voltage independent. In addition, no major physiological effects of the inactivated p13 gene could be detected under normal growth conditions. The inactivation of p13 is the first reported inactivation of a gene encoding an integral outer membrane protein in B. burgdorferi. Here, we describe both genetic and biophysical experiments indicating that P13 in B. burgdorferi is an outer membrane protein with porin activity.

Differential immune response to the variable surface loop antigen of P66 of Borrelia burgdorferi sensu lato species in geographically diverse populations of lyme borreliosis patients

We have studied the immune response to a variable surface-exposed loop region of the P66 outer membrane protein from Borrelia burgdorferi sensu lato by using an enzyme immunoassay. Lyme borreliosis populations found in North America and Sweden were preferentially more seroreactive to P66 from their respective regional species, namely, B. burgdorferi sensu stricto and B. garinii and B. afzelii, respectively.

Characterization of the P13 membrane protein of Borrelia burgdorferi by mass spectrometry

Borrelia burgdorferi sensu lato is a tick-borne pathogen that causes Lyme disease. The characterization of membrane proteins from this and other pathogens may yield a better understanding of the mechanisms of infection and information useful for vaccine design. Characterization of the highly hydrophobic Borrelia outer membrane component P13 from a mutant (OspA- OspB- OspC- and OspD-) strain was undertaken by use of a combination of mass spectrometric methods. In a previous investigation, an electrospray ionization (ESI) mass spectrum of the intact protein provided an average molecular weight that was 20 Da lower than the predicted molecular weight. The mass deviation could be explained by a modification of the N-terminus of the protein such as pyroglutamylation (-17 Da) in combination with the experimental error of measurement, however more information was required. New structural information for this membrane protein was provided by peptide mapping with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF MS) and sequencing with ESI-quadrupole-TOF tandem MS.

P13, an integral membrane protein of Borrelia burgdorferi, is C-terminally processed and contains surface-exposed domains

To elucidate antigens present on the bacterial surface of Borrelia burgdorferi sensu lato that may be involved in pathogenesis, we characterized a protein, P13, with an apparent molecular mass of 13 kDa. The protein was immunogenic and was expressed in large amounts during in vitro cultivation compared to other known antigens. An immunofluorescence assay, immunoelectron microscopy, and protease sensitivity assays indicated that P13 is surface exposed. The deduced sequence of the P13 peptide revealed a possible signal peptidase type I cleavage site, and computer analysis predicted that P13 is an integral membrane protein with three transmembrane-spanning domains. Mass spectrometry, in vitro translation, and N- and C-terminal amino acid sequencing analyses indicated that P13 was posttranslationally processed at both ends and modified by an unknown mechanism. Furthermore, p13 belongs to a gene family with five additional members in B. burgdorferi sensu stricto. The p13 gene is located on the linear chromosome of the bacterium, in contrast to five paralogous genes, which are located on extrachromosomal plasmids. The size of the p13 transcript was consistent with a monocistronic transcript. This new gene family may be involved in functions that are specific for this spirochete and its pathogenesis.

Isolation of Lyme disease Borrelia from puffins (Fratercula arctica) and seabird ticks (Ixodes uriae) on the Faeroe Islands

This is the first report on the isolation of Lyme disease Borrelia from seabirds on the Faeroe Islands and the characteristics of its enzootic cycle. The major components of the Borrelia cycle include the puffin (Fratercula arctica) as the reservoir and Ixodes uriae as the vector. The importance of this cycle and its impact on the spread of human Lyme borreliosis have not yet been established. Borrelia spirochetes isolated from 2 of 102 sampled puffins were compared to the borreliae previously obtained from seabird ticks, I. uriae. The rrf-rrl intergenic spacer and the rrs and the ospC genes were sequenced and a series of phylogenetic trees were constructed. Sequence data and restriction fragment length polymorphism analysis grouped the strains together with Borrelia garinii. In a seroepidemiological survey performed with residents involved in puffin hunting on the Faeroe Islands, 3 of 81 serum samples were found to be positive by two commonly used clinical tests: a flagellin-based enzyme-linked immunosorbent assay (ELISA) and Western blotting. These three positive serum samples also had high optical density values in a whole-cell ELISA. The finding of seropositive Faeroe Islanders who are regularly exposed to I. uriae indicate that there may be a transfer of B. garinii by this tick species to humans.

Efficiency of automotive cabin air filters to reduce acute health effects of diesel exhaust in human subjects

OBJECTIVES

To evaluate the efficiency of different automotive cabin air filters to prevent penetration of components of diesel exhaust and thereby reduce biomedical effects in human subjects. Filtered air and unfiltered diluted diesel exhaust (DDE) were used as negative and positive controls, respectively, and were compared with exposure to DDE filtered with four different filter systems.

METHODS

32 Healthy non-smoking subjects (age 21-53) participated in the study. Each subject was exposed six times for 1 hour in a specially designed exposure chamber: once to air, once to unfiltered DDE, and once to DDE filtered with the four different cabin air filters. Particle concentrations during exposure to unfiltered DDE were kept at 300 micrograms/m3. Two of the filters were particle filters. The other two were particle filters combined with active charcoal filters that might reduce certain gaseous components. Subjective symptoms were recorded and nasal airway lavage (NAL), acoustic rhinometry, and lung function measurements were performed.

RESULTS

The two particle filters decreased the concentrations of diesel exhaust particles by about half, but did not reduce the intensity of symptoms induced by exhaust. The combination of active charcoal filters and a particle filter significantly reduced the symptoms and discomfort caused by the diesel exhaust. The most noticable differences in efficacy between the filters were found in the reduction of detection of an unpleasant smell from the diesel exhaust. In this respect even the two charcoal filter combinations differed significantly. The efficacy to reduce symptoms may depend on the abilities of the filters investigated to reduce certain hydrocarbons. No acute effects on NAL, rhinometry, and lung function variables were found.

CONCLUSIONS

This study has shown that the use of active charcoal filters, and a particle filter, clearly reduced the intensity of symptoms induced by diesel exhaust. Complementary studies on vehicle cabin air filters may result in further diminishing the biomedical effects of diesel exhaust in subjects exposed in traffic and workplaces.

Surface exposure and species specificity of an immunoreactive domain of a 66-kilodalton outer membrane protein (P66) of the Borrelia spp. that cause Lyme disease

A chromosomally encoded 66-kDa protein (P66) of Borrelia spp. that cause Lyme disease has previously been shown to be associated with the spirochetal outer membrane. A topological model of P66 predicts a surface-exposed fragment which links the N- and C-terminal intramembranous domains of the protein (J. Bunikis, L. Noppa, and S. Bergström, FEMS Microbiol. Lett. 131:139-145, 1995). In the present study, an immunogenic determinant of P66 was identified by a comparison of the immunoreactivities of different fragments of P66 generated either by proteolytic treatment of intact spirochetes or as recombinant proteins expressed in Escherichia coli. The immune response to P66 during natural infection was found to be directed against the predicted surface domain which comprises amino acids at positions 454 through 491. A sequence comparison revealed considerable polymorphism of the surface domains of P66 proteins of different Lyme disease-causing Borrelia species. Five sequence patterns of this domain were observed in the B. garinii strains studied. In contrast, sequences of the relevant part of P66 of the B. afzelii and B. burgdorferi sensu stricto isolates studied were identical within the respective species. In immunoblotting, 5 of 17 (29.4%) sera from North American patients with early disseminated or persistent Lyme disease reacted against P66 of B. burgdorferi sensu stricto B31. These sera, however, failed to recognize P66 of B. afzelii and B. garinii, as well as an analog of P66 in the relapsing fever agent, B. hermsii. In conclusion, the topological model of P66 is supported by the demonstration of an apparent surface localization of an immunoreactive domain of this protein. Furthermore, analogous to the plasmid-encoded borrelial outer surface proteins, the predicted surface-exposed portion of chromosomally encoded P66 appears to be antigenically heterogenous.

Echocardiographic findings in patients with primary Sjögren's syndrome

Cardiac involvement in 27 consecutive patients fulfilling the criteria for primary Sjögren's syndrome was evaluated using echo-doppler-cardiography. A clinical physical examination showed that the heart was normal in all patients. Nine (33%) had signs of present or previous pericarditis with effusion and/or fibrin deposition, four of them had chest symptoms. The pericarditis patients were slightly older, had significantly shorter disease duration, had significantly increased levels of orosomucoid and haptoglobin, and were significantly more often antinuclear-antibody positive than those without pericarditis. Of the echocardiographic measurements, the left ventricular systolic dimension was significantly smaller and the fractional shortening of the left ventricle significantly higher in the pericarditis patients. However, four of the nine pericarditis patients had localized hypokinesia of the left ventricle, all with unspecific ECG changes, while only one without pericarditis showed this symptom. No patient had low voltage, ST-T elevation or conduction abnormalities. Mitral valvular thickening was found in one patient and age-related sclerosis of the aortic cusps appeared in some.

Features of Sjögren's syndrome in patients with primary biliary cirrhosis

Twenty-six consecutive patients with primary biliary cirrhosis (PBC) from northern Sweden were studied regarding the occurrence and features of Sjögren's syndrome (SS). In more than 50% of the patients the rose bengal dye test showed conjunctival and/or corneal staining. In six patients keratoconjunctivitis sicca (KCS) was present with positive rose bengal and Schirmer tests. In a further three patients only the results of the Schirmer tests were abnormal. Radiological findings of sialectasia were demonstrated in six patients, five of whom had KCS. Two of the seven patients who fulfilled our criteria for Sjögren's syndrome were HLA-B8 positive. A high prevalence of increased immune globulins and rheumatic factor was found, but this did not correlate with the presence of Sjögren's syndrome. Some features of Sjögren's syndrome were found in 73% of PBC patients, and keratoconjunctivitis sicca and/or sialectasia were found in 27% of PBC patients. This constitutes a high frequency of secondary manifestations of the liver disease.

Immunohistochemical analyses of autoimmune sialadenitis in man

The immunoreactivity pattern for different monoclonal antibodies to cytokeratins and to vimentin in epimyoepithelial islands typical for glands of patients with Sjögren's syndrome has been compared with that of normal parotid gland tissue. Two types of epithelial island cells were observed: one had an intermediate filament protein pattern similar to that of ordinary duct epithelial cells of normal parotid gland. The other had an intermediate filament protein pattern typical of myoepithelial and/or basal duct cells in normal glands. Thus, we conclude that the islands are composed of a mixed population of gland cells on the basis of their content of cytokeratins or of cytokeratins and vimentin. These cells might originate from pluripotential reserve cells or from ordinary duct, myoepithelial and/or basal duct cells which may have undergone metaplasia.

The clinical picture of benign lympho-epithelial lesion

The histopathological diagnosis 'benign lympho-epithelial lesion' characterizes the major salivary gland disease in Sjögren's syndrome. It is not known if all cases with microscopically diagnosed benign lympho-epithelial lesion are variants of Sjögren's syndrome. The present clinical investigation showed that in 19 patients with the microscopical diagnosis of lympho-epithelial lesion, 84% fulfilled all criteria of Sjögren's syndrome. The rheumatoid factor and/or antinuclear factor was found in 84% and M-component was present in 16%. Sialography revealed sialectasis in all parotid glands. Salivary gland enlargement was found in 79%, and keratoconjunctivitis sicca in 89% of the patients. Systemic disease was found in 32%. The disease in the 2 patients with M-component took a malignant course, culminating in immunoblastic sarcoma and myelomatosis. The clinical diagnosis 'autoimmune sialadenitis' is proposed for the oral and salivary gland component is Sjögren's syndrome.

Hydralazine-induced relapsing polychondritis-like syndrome. Report of a case with severe chronic laryngeal complications

Relapsing polychondritis is a rare disease of uncertain etiology, characterized by inflammation of cartilage. Cartilage of the respiratory tract is engaged in more than half of all cases. Hydralazine-induced systemic lupus erythematosis (SLE) is a well known disease. Females who are slow acetylators and are HLA-DR4 positive when treated with hydralazine are at serious risk of contracting SLE syndrome. We describe here a woman, treated for 10 years with hydralazine, who was a slow acetylator and was HLA-DR4 positive and who presented with a relapsing polychondritis and ultimately required a permanent tracheostoma. To our knowledge, this is the first published case of relapsing polychondritis induced by hydralazine.

Malignant salivary gland tumours in children

Nine malignant salivary gland tumours in children, reported to the Swedish Cancer Registry between 1958 to 1980, are reviewed. All tumours appeared in the parotid gland. Five cases were muco-epidermoid carcinoma of low-grade malignancy. All patients but one were treated with surgery. The postoperative follow-up period is 1 to 21 years. Three children have died, 2 of tumour disease, 1 and 18 years respectively after diagnosis. In the other children there are no signs of recurrence. Salivary gland tumours in children must be treated according to the same principles generally accepted for adult salivary gland neoplasias.

The autoimmune submandibular sialoadenitis of the NZB/NZW hybrid mice. A light and electron microscopical investigation

An electron microscopic study of the submandibular salivary gland lesion occurring in the NZB/NZW F1 hybrid mice was performed, and the findings were discussed and correlated to the autoimmune salivary gland disease observed in patients with Sjögren's syndrome. Within the submandibular salivary gland of this mouse strain focal infiltrates of mononuclear inflammatory cells were observed. Lymphoid cells were observed inside the basal lamina of acini and ducts, leading to destruction of these glandular units. The typical duct cell proliferation found in the autoimmune sialoadenitis of Sjögren's syndrome with the formation of the typical epimyoepithelial islands was not found in the submandibular glands of NZB/NZW mice.

Laryngeal chondrosarcoma in Sweden

Between 1958 and 1972, 5 cases of posterior cricoid chondrosarcoma were reported to the Swedish Cancer Registry. These cases, and one recently observed case of laryngeal chondrosarcoma, are presented in this study of one female and five male patients. The tumours grow slowly and recur locally, but have not metastasized, and none of the patients has died from tumour disease. The clinical and morphological findings indicate that these tumours represent secondary chondrosarcomas developing from pre-existing benign ecchondromas. The reason for the uniformity as to localization is not known. The microscopic appearance varied in different parts of the same tumour. The presently obtained data and review of the literature indicate that laryngeal chondrosarcomas are extremely rare, locally invasive, but usually not metastasizing tumours. Conservative laryngeal operation is suggested as primary treatment. Total laryngectomy is necessary only after local recurrences involving a major portion of the cricoid cartilage.

Ultrastructural observations on the parotitis autoimmunica in the NZB/NZW hybrid mice

The lesions of the spontaneously occurring sialoadenitis in the parotid gland of New Zealand Black/New Zealand White (NZB/NZW) hybrid mice were studied with the light microscope and the electron microscope. The inflammatory mononuclear cell infiltrates of the glands observed adjacent to glandular vessels and ducts were found to consist of several different cell types. Lymphoid cells (large, medium sized and small lymphocytes) were the most common, but plasma cells, histiocytes and macrophages were also encountered. Furthermore lymphoid cells were frequently observed inside the basement membrane of acini as well as INTERcalated ducts. Evidence of cell damage of the epithelium invaded by lymphoid elements included loss of cytoplasmic density, vesiculation of the endoplasmic reticulum, the appearance of cytoplasmic vacuoles, and cellular lysis. All the animals studied displayed moderate to advanced glomerular, wire-loop lesions in the kidneys. The light and electron microscopic findings indicate that the parotitis in NZB/NZW mice is basically a vasculitis. Duct cell proliferation and epimyo-epithelial island formation, which are common features in Sjögren's syndrome, are totally lacking in the material studied.

Localization of somatostatin-like immunoreactivity in the pancreatic islets of the hagfish, Myxine glutinosa and the lamprey Lampetra fluviatilis

Somatostatin-like immunofluorescence has been found by immunostaining in cells of the bile duct mucosa and pancreatic islet parenchyma of the hagfish, Myxine glutinosa, and the islet lobules of the lamprey, Lampetra fluviatilis.

On the occurrence of argyrophil cells in salivary glands

Salivary glands (parotid, submandibular and sublingual glands) of nine mammalian species were investigated with respect to presence and localization of argyrophil and argentaffin cells. With the exception of the parotid gland of the rat, no positive staining was observed within the examined glands. In the rat parotid distinctly argyrophil cells could be demonstrated in the intercalated ducts. Histochemical studies of the cells, ultrastructural analysis of their cytoplasmic granules as well as their reactions to certain drugs indicate that these cells are of exocrine rather than of endocrine nature. After a subcutaneous injection of pilocarpine, the intensity of the argyrophil staining was markedly reduced. No specific catecholamine fluorescence could be detected within the cells, not even after pretreatment of the animals with high doses of L-DOPA. The membrane-bounded cytoplasmic granules of the intercalated duct cells furthermore displayed a strong positive staining reaction after treatment of ultrathin Vestopal sections with the periodic acid-chromic acid-silver technique of Rambourg et al. (1969).

Survival after haemorrhage from the brachiocephalic truncus following tracheostomy

A patient with two massive haemorrhages from the brachiocephalic truncus after tracheostomy is reported. An analysis of 6 previously reported long-term survivors following this complication shows that the initial care in controlling the haemorrhage is of major importance. The operation method of choice is permanent division of the brachiocephalic truncus. Transitory or no neurological postoperative complications were found.

Annulate lamellae and crystalline inclusions in granular endoplasmic reticulum of the islet organ and associated tissues of a cyclostome, Myxine glutinosa

Cytoplasmic annylate lamellae were found in the islet organ of a cyclostome, the hagfish (Myxine glutinosa), predominantly in cells interpreted as young proliferating beta-cells, and also in endocrine cells and enterocytes of the bile duct and gut and in the endothelial cells of small blood vessels. A close association was observed annulate lamellae and granular endoplasmic reticulum. Both in cells with and in those without annulate lamellae, crystalline inclusions of proteinaceous nature were seen in granular endoplasmic reticulum. These inclusions were occasionally closely associated to annulate lamellae, and a direct continuity could be seen between granular endoplasmic reticulum and the outer nuclear membrane surrounding an inclusion partially situated in the perinuclear cisterna. Rod-shaped structures and rounded electron dense bodies were seen in the nuclei of some islet parenchymal cells. The presence of annulate lamellae in the islet organ and associated tissues of Myxine glutinosa is believed to be related to the very high phylogenetic age of this species. The close association observed between annulate lamellae, granular endoplasmic reticulum, crystalline inclusions, and sometimes also nuclear membranes, may be of functional significance.

The nitroblue tetrazolium (NBT) test and white blood cell count in acute throat infections

The clinical value of the NBT test and of leucocyte counts in the aetiological differentiation of acute throat infections was investigated. In our hands a frequency of less than 13% NBT positive neutrophils is considered as normal and a test value above 19% as "positive", i.e. indicating a bacterial infection. More than 19% or more than 1 800 NBT positive neutrophils per mm-3 blood were found in 10 of 18 patients with an infection caused by beta-haemolytic streptococci, in 1 of 2 patients with a Mycoplasma pneumoniae infection and in 1 patient with both a streptococcal and mycoplasmal infection, but in none of 19 patients with a viral infection. Since 8 of 18 patients with streptococcal throat infection had normal NBT test results, the NBT test apparently is of limited value in the early recognition of these infections. A high NBT test value would however support the diagnosis. The white blood cell and neutrophil counts were of little value in the differentiation between streptococcal and viral throat infection.