Detection of trace sub-micron (nano) plastics in water samples using pyrolysis-gas chromatography time of flight mass spectrometry (PY-GCToF)

The identification and quantification of micro and nanoplastics (MPs and NPs respectively) requires the development of standardised analytical methods. Thermal analysis methods are generally not considered a method of choice for MPs analysis, especially in aqueous samples due to limited sample size introduction to the instrument, decreasing the detection levels. In this article, pyrolysis - Gas chromatography time of flight mass spectrometry (Py-GCToF) is used as a method of choice for detection of MPs and NPs due to its unprecedented detection capabilities, in combination with PTFE membranes as sample support, allow for smaller particle sizes (>0.1 μm) in water samples to be identified. The utilisation of these widely used membranes and the identification of several and specific (marker) ions for the three plastics in study (polypropylene (PP), polystyrene (PS) and polyvinyl chloride (PVC)), allows for the extraction of individual plastics from complex signals at trace levels. The method was validated against a number of standards, containing known quantities of MPs. Detection levels were then determined for PVC and PS and were found to be below <50 μg/L, with repeatable data showing good precision (%RSD <20%). Further verification of this new method was achieved by the analysis of a complex sample, sourced from a river. The results were positive for the presence of PS with a semi-quantifiable result of 241.8 μg/L. Therefore PY-GCToF seems to be a fit for purpose method for the identification of MPs and NPs from complex mixtures and matrices which have been deposited on PTFE membranes.

Summary Care Records in urgent and emergency care in England

Summary Care Records (SCRs) have been created for more than 50% of the population of England. The number is increasing at about 100,000 records a week. Fewer than 1.5% of people have elected not to have a SCR. SCRs contain updated details of patient medication, allergies and adverse reactions, electronically extracted from the GP record. A patient and their GP can also agree to have additional information included. SCRs are being viewed by authorised healthcare staff in urgent and emergency care settings all over England. Benefits are being reported in relation to increased patient safety, improved clinical decision making, improved efficiency and improved quality of care. NHS England strongly supports the uptake and adoption of SCRs by Trusts in England.

Do faculty and resident physicians discuss their medical errors?

BACKGROUND

Discussions about medical errors facilitate professional learning for physicians and may provide emotional support after an error, but little is known about physicians' attitudes and practices regarding error discussions with colleagues.

METHODS

Survey of faculty and resident physicians in generalist specialties in Midwest, Mid-Atlantic and Northeast regions of the US to investigate attitudes and practices regarding error discussions, likelihood of discussing hypothetical errors, experience role-modelling error discussions and demographic variables.

RESULTS

Responses were received from 338 participants (response rate = 74%). In all, 73% of respondents indicated they usually discuss their mistakes with colleagues, 70% believed discussing mistakes strengthens professional relationships and 89% knew at least one colleague who would be a supportive listener. Motivations for error discussions included wanting to learn whether a colleague would have made the same decision (91%), wanting colleagues to learn from the mistake (80%) and wanting to receive support (79%). Given hypothetical scenarios, most respondents indicated they would likely discuss an error resulting in no harm (77%), minor harm (87%) or major harm (94%). Fifty-seven percent of physicians had tried to serve as a role model by discussing an error and role-modelling was more likely among those who had previously observed an error discussion (OR 4.17, CI 2.34 to 7.42).

CONCLUSIONS

Most generalist physicians in teaching hospitals report that they usually discuss their errors with colleagues, and more than half have tried to role-model discussions. However, a significant number of these physicians report that they do not usually discuss their errors and some do not know colleagues who would be supportive listeners.

Reduction of mortality in specific-pathogen-free layer chickens by a caprine serum fraction after infection with Pasteurella multocida

Caprine serum was fractionated by size, and its proteinaceous material <8,000 Da [caprine serum fraction immunomodulator 2 (CSF-I2)] was evaluated for its ability to impart immunoresistance to specific-pathogen-free (SPF) layer chickens. The SPF layers were challenged with 18 to 30 cfu of Pasteurella multocida X-73 (serotype 1) at 5 wk of age. A high degree of mortality was apparent 24 and 48 h later (62+/-14% and 88+/-7%, respectively). Mortality observed after 48 h was minimal. Noting the rapid onset of mortality, we administered CSF-I2 (material that expressed no direct antimicrobial activity but was believed to be an immunostimulant) 1 d before challenge and coincident to time of challenge. The group of birds that received CSF-I2 (either 5 or 10 mg per administration) expressed significant reduction in mortality throughout the 1-wk study period. Reduction in mortality appeared to be dose dependent. Birds that received two administrations of 10 mg CSF-I2 had significantly fewer deaths than did the group of birds that received half that amount. No deaths were recorded through 24 h, whereas, at 48 h, the percentage mortality was 13 in CSF-I2-treated birds. This study demonstrates that one or more small molecular weight compounds isolated from caprine serum were able to reduce mortality in SPF layers infected with Pasteurella multocida.

Pep3p/Pep5p complex: a putative docking factor at multiple steps of vesicular transport to the vacuole of Saccharomyces cerevisiae

Pep3p and Pep5p are known to be necessary for trafficking of hydrolase precursors to the vacuole and for vacuolar biogenesis. These proteins are present in a hetero-oligomeric complex that mediates transport at the vacuolar membrane. PEP5 interacts genetically with VPS8, implicating Pep5p in the earlier Golgi to endosome step and/or in recycling from the endosome to the Golgi. To understand further the cellular roles of Pep3p and Pep5p, we isolated and characterized a set of pep3 conditional mutants. Characterization of mutants revealed that pep3(ts) mutants are defective in the endosomal and nonendosomal Golgi to vacuole transport pathways, in the cytoplasm to vacuole targeting pathway, in recycling from the endosome back to the late Golgi, and in endocytosis. PEP3 interacts genetically with two members of the endosomal SNARE complex, PEP12 (t-SNARE) and PEP7 (homologue of mammalian EEA1); Pep3p and Pep5p associate physically with Pep7p as revealed by two-hybrid analysis. Our results suggest that a core Pep3p/Pep5p complex promotes vesicular docking/fusion reactions in conjunction with SNARE proteins at multiple steps in transport routes to the vacuole. We propose that this complex may be responsible for tethering transport vesicles on target membranes.

Malignant spinal neurofibrosarcoma

STUDY DESIGN

A report of a case of metastatic spinal neurofibrosarcoma.

OBJECTIVE

To document metastatic neurofibrosarcoma as a cause of spinal cord compression and to review the literature.

SUMMARY OF BACKGROUND DATA

Three previously reported cases of metastatic neurofibrosarcoma of the spine were reviewed.

METHODS

The patient's clinical record and radiologic investigations as well as the result of a search of the English literature are reported. Magnetic resonance images, computed tomographic scans, and histology photomicrographs are displayed.

RESULTS

Paraparesis developed in this patient, due to a posterior extradural thoracic spinal cord compression by a neurofibrosarcoma believed to be metastatic from a neurofibrosarcoma of the femoral nerve.

CONCLUSIONS

Malignant spinal metastasis remains a rare complication of neurofibromatosis, with a very poor prognosis.

Orbital metastasis due to interval lobular carcinoma of the breast: a potential mimic of lymphoma

A 53-year-old woman had an orbital mass composed of a neoplastic small round cell infiltrate and no apparent extraorbital primary tumor. Although the initial diagnosis was primary orbital lymphoma, a combination of mucin histochemistry and immunohistochemical staining for cytokeratin and estrogen receptors led to the discovery of an impalpable lobular carcinoma of the breast. We discuss how detailed histopathological assessment can lead to beneficial therapy.

Water transport across yeast vacuolar and plasma membrane-targeted secretory vesicles occurs by passive diffusion

To determine whether solute transport across yeast membranes was facilitated, we measured the water and solute permeations of vacuole-derived and late secretory vesicles in Saccharomyces cerevisiae; all permeations were consistent with passive diffusive flow. We also overexpressed Fps1p, the putative glycerol facilitator in S. cerevisiae, in secretory vesicles but observed no effect on water, glycerol, formamide, or urea permeations. However, spheroplasts prepared from the strain overexpressing Fps1p showed enhanced glycerol uptake, suggesting that Fps1p becomes active only upon insertion in the plasma membrane.

Spontaneous intralesional haemorrhage in dysembryoplastic neuroepithelial tumours: a series of five cases

Five patients with dysembryoplastic neuroepithelial tumour (DNT) showing extensive secondary haemorrhage, a finding not previously associated with these neoplasms, are described. The clinical presentations, neuroimaging findings, and histopathological features of these patients are reviewed. One patient, a previously asymptomatic 12 year old girl, presented with an acute intracerebral haemorrhage into a DNT. A further four young adults with histories of intractable partial and generalised seizures dating from childhood showed significant chronic haemorrhages within DNT, the MRI appearances in one patient giving a false impression of a cavernoma. Histopathology disclosed vascular abnormalities within these tumours which, together with other factors discussed, may have predisposed these tumours to haemorrhage.

The PBN1 gene of Saccharomyces cerevisiae: an essential gene that is required for the post-translational processing of the protease B precursor

The vacuolar hydrolase protease B in Saccharomyces cerevisiae is synthesized as an inactive precursor (Prb1p). The precursor undergoes post-translational modifications while transiting the secretory pathway. In addition to N- and O-linked glycosylations, four proteolytic cleavages occur during the maturation of Prb1p. Removal of the signal peptide by signal peptidase and the autocatalytic cleavage of the large amino-terminal propeptide occur in the endoplasmic reticulum (ER). Two carboxy-terminal cleavages of the post regions occur in the vacuole: the first cleavage is catalyzed by protease A and the second results from autocatalysis. We have isolated a mutant, pbn1-1, that exhibits a defect in the ER processing of Prb1p. The autocatalytic cleavage of the propeptide from Prb1p does not occur and Prb1p is rapidly degraded in the cytosol. PBN1 was cloned and is identical to YCL052c on chromosome III. PBN1 is an essential gene that encodes a novel protein. Pbn1p is predicted to contain a sub-C-terminal transmembrane domain but no signal sequence. A functional HA epitope-tagged Pbn1p fusion localizes to the ER. Pbn1p is N-glycosylated in its amino-terminal domain, indicating a lumenal orientation despite the lack of a signal sequence. Based on these results, we propose that one of the functions of Pbn1p is to aid in the autocatalytic processing of Prb1p.

Pth1/Vam3p is the syntaxin homolog at the vacuolar membrane of Saccharomyces cerevisiae required for the delivery of vacuolar hydrolases

The PEP12 homolog Pth1p (Pep twelve homolog 1) is predicted to be similar in size to Pep12p, the endosomal syntaxin homolog that mediates docking of Golgi-derived transport vesicles and, like other members of the syntaxin family, is predicted to be a cytoplasmically oriented, integral membrane protein with a C-terminal transmembrane domain. Kinetic analyses indicate that deltapth1/vam3 mutants fail to process the soluble vacuolar hydrolase precursors and that PrA, PrB and most of CpY accumulate within the cell in their Golgi-modified P2 precursor forms. This is in contrast to a pep12 mutant in which P2CpY is secreted from the cell. Furthermore, pep12 is epistatic to pth1/vam3 with respect to the CpY secretion phenotype. Alkaline phosphatase, a vacuolar membrane hydrolase, accumulates in its precursor form in the deltapth1/vam3 mutant. Maturation of pro-aminopeptidase I, a hydrolase precursor delivered directly to the vacuole from the cytoplasm, is also blocked in the deltapth1/vam3 mutant. Subcellular fractionation localizes Pth1/Vam3p to vacuolar membranes. Based on these data, we propose that Pth1/Vam3p is the vacuolar syntaxin/t-SNARE homolog that participates in docking of transport vesicles at the vacuolar membrane and that the function of Pth1/Vam3p impinges on at least three routes of protein delivery to the yeast vacuole.

Genetic interaction with vps8-200 allows partial suppression of the vestigial vacuole phenotype caused by a pep5 mutation in Saccharomyces cerevisiae

pep5 mutants of Saccharomyces cerevisiae accumulate inactive precursors to the vacuolar hydrolases. In addition, they show a vestigial vacuole morphology and a sensitivity to growth on media containing excess divalent cations. This pleiotropic phenotype observed for pep5::TRP1 mutants is partially suppressed by the vps8-200 allele. pep5::TRP1 vps8-200 mutants show near wild-type levels of mature-sized soluble vacuolar hydrolases, growth on zinc-containing medium, and a more "wild-type" vacuolar morphology; however, aminopeptidase I and alkaline phosphatase accumulate as precursors. These data suggest that Pep5p is a bifunctional protein and that the TRP1 insertion does not eliminate function, but results in a shorter peptide that can interact with Vps8-200p, allowing for partial function. vps8 deletion/disruption mutants contain a single enlarged vacuole. This genetic interaction was unexpected, since Pep5p was thought to interact more directly with the vacuole, and Vps8p is thought to play a role in transport between the Golgi complex and the prevacuolar compartment. The data are consistent with Pep5p functioning both at the site of Vps8p function and more closely proximal to the vacuole. They also provide evidence that the three transport pathways to the vacuole either converge or share gene products at late step(s) in the pathway(s).

Genetic interactions between a pep7 mutation and the PEP12 and VPS45 genes: evidence for a novel SNARE component in transport between the Saccharomyces cerevisiae Golgi complex and endosome

The PEP7 gene from Saccharomyces cerevisiae encodes a 59-kD hydrophilic polypeptide that is required for transport of soluble vacuolar hydrolase precursors from the TGN to the endosome. This study presents the results of a high-copy suppression analysis of pep7-20 mutant phenotypes. This analysis demonstrated that both VPS45 and PEP12 are allele-specific high-copy suppressors of pep7-20 mutant phenotypes. Overexpression of VPS45 was able to completely suppress the Zn2+ sensitivity and partially suppress the carboxypeptidase Y deficiency. Overexpression of PEP12 was able to do the same, but to a lesser extent. Vps45p and Pep12p are Sec1p and syntaxin (t-SNARE) homologues, respectively, and are also thought to function in transport between the TGN and endosome. Two additional vacuole pathway SNARE complex homologues, Vps33p (Sec1p) and Pth1p (syntaxin), when overexpressed, were unable to suppress pep7-20 or any other pep7 allele, further supporting the specificity of the interactions of pep7-20 with PEP12 and VPS45. Because several other vesicle docking/fusion reactions take place in the cell without discernible participation of Pep7p homologues, we suggest that Pep7p is a step-specific regulator of docking and/or fusion of TGN-derived transport vesicles onto the endosome.

Pep7p provides a novel protein that functions in vesicle-mediated transport between the yeast Golgi and endosome

Saccharomyces cerevisiae pep7 mutants are defective in transport of soluble vacuolar hydrolases to the lysosome-like vacuole. PEP7 is a nonessential gene that encodes a hydrophilic protein of 515 amino acids. A cysteine-rich tripartite motif in the N-terminal half of the polypeptide shows striking similarity to sequences found in many other eukaryotic proteins. Several of these proteins are thought to function in the vacuolar/lysosomal pathway. Mutations that change highly conserved cysteine residues in this motif lead to a loss of Pep7p function. Kinetic studies demonstrate that Pep7p function is required for the transport of the Golgi-precursors of the soluble hydrolases carboxypeptidase Y, proteinase A, and proteinase B to the endosome. Integral membrane hydrolase alkaline phosphatase is transported to the vacuole by a parallel intracellular pathway that does not require Pep7p function. pep7 mutants accumulate a 40-60-nm vesicle population, suggesting that Pep7p functions in a vesicle consumption step in vesicle-mediated transport of soluble hydrolases to the endosome. Whereas pep7 mutants demonstrate no defects in endocytic uptake at the plasma membrane, the mutants demonstrate defects in transport of receptor-mediated macromolecules through the endocytic pathway. Localization studies indicate that Pep7p is found both as a soluble cytoplasmic protein and associated with particulate fractions. We conclude that Pep7p functions as a novel regulator of vesicle docking and/or fusion at the endosome.

Regulation of the proteinase B structural gene PRB1 in Saccharomyces cerevisiae

The expression of PRB1, the gene that encodes the precursor to the soluble vacuolar proteinase B (PrB) in Saccharomyces cerevisiae, is regulated by carbon and nitrogen sources and by growth phase. Little or no PRB1 mRNA is detectable during exponential growth on glucose as the carbon source; it begins to accumulate as cells exhaust the glucose. Previous work has shown that glucose repression of PRB1 transcription is not mediated by HXK2 or by the SNF1, SNF4, and SNF6 genes (C. M. Moehle and E. W. Jones, Genetics 124:39-55, 1990). We analyzed the effects of mutations in the MIG1, TUP1, and GRR1 genes on glucose repression of PRB1 and found that mutations in each partially alleviate glucose repression. tup1 and mig1 mutants fail to translocate all of the Prb1p into the lumen of the endoplasmic reticulum. A screen for new mutants revealed mutations in MIG1 and REG1, genes already known to regulate glucose repression, as well as in three new genes that we have named PBD1 to PBD3; all cause derepressed expression. Mutations that result in failure to completely derepress PRB1 were also identified in two new genes, named PND1 and PND2. Good nitrogen sources, like ammonia, repress PRB1 transcription; mutations in URE2 do not affect this response. Derepression upon transfer to a poor nitrogen source is dependent upon GLN3.

Novel syntaxin homologue, Pep12p, required for the sorting of lumenal hydrolases to the lysosome-like vacuole in yeast

pep12/vps6 mutants of Saccharomyces cerevisiae are defective in delivery of soluble vacuolar hydrolases to the vacuole. Morphological analysis by electron microscopy revealed that pep12 cells accumulate 40- to 50-nm vesicles. Furthermore, pep12 cells have enlarged vacuoles characteristic of class D pep/vps mutants. PEP12 encodes a protein of 288 amino acids that has a C-terminal hydrophobic region and shares significant sequence similarity with members of the syntaxin protein family. These proteins appear to participate in the docking and fusion of intracellular transport vesicles. Pep12p is the first member of the syntaxin family to be implicated in transport between the Golgi and the vacuole/lysosome. Pep12p-specific polyclonal antisera detected a 35-kDa protein that fractionated as an integral membrane protein. Subcellular fractionation experiments revealed that Pep12p was associated with membrane fractions of two different densities; the major pool (approximately 90%) of pep12p may associate with the endosome, while a minor pool (approximately 10%) cofractionated with the late Golgi marker Kex2p. These observations suggest that Pep12p may mediate the docking of Golgi-derived transport vesicles at the endosome.

An immunocytochemical assessment of 19 cases of cutaneous angiosarcoma

Four endothelial cell markers, two selective cytokeratin markers and a monoclonal smooth muscle antibody (SMA) were employed in the assessment of 19 cases of cutaneous angiosarcoma classified according to their degree of tumour differentiation. No labelling was seen for SMA or with cytokeratin markers MNF116 and CBL170. Expression of factor VIII-related antigen was seen in two tumours and positivity for CD34 (QBend 10 antibody) was found in four tumours. By contrast the pan-endothelial cell marker Ulex europeaus agglutinin 1 (UEA-1) and the CD31 marker JC70A labelled all cases of cutaneous angiosarcoma with the exception of one poorly differentiated tumour. These data confirm the endothelial cell origin of angiosarcoma, they demonstrate that CD31 and UEA1 are reliable markers in routinely processed tissue, and they suggest a lymphatic derivation for the tumour. This finding is in marked contrast to Kaposi's sarcoma where CD34 is the most reliable marker.

vph6 mutants of Saccharomyces cerevisiae require calcineurin for growth and are defective in vacuolar H(+)-ATPase assembly

We have characterized a Saccharomyces cerevisiae mutant strain that is hypersensitive to cyclosporin A (CsA) and FK506, immunosuppressants that inhibit calcineurin, a serine-threonine-specific phosphatase (PP2B). A single nuclear mutation, designated cev1 for calcineurin essential for viability, is responsible for the CsA-FK506-sensitive phenotype. The peptidyl-prolyl cis-trans isomerases cyclophilin A and FKBP12, respectively, mediate CsA and FK506 toxicity in the cev1 mutant strain. We demonstrate that cev1 is an allele of the VPH6 gene and that vph6 mutant strains fail to assemble the vacuolar H(+)-ATPase (V-ATPase). The VPH6 gene was mapped on chromosome VIII and is predicted to encode a 181-amino acid (21 kD) protein with no identity to other known proteins. We find that calcineurin is essential for viability in many mutant strains with defects in V-ATPase function or vacuolar acidification. In addition, we find that calcineurin modulates extracellular acidification in response to glucose, which we propose occurs via calcineurin regulation of the plasma membrane H(+)-ATPase PMA1. Taken together, our findings suggest calcineurin plays a general role in the regulation of cation transport and homeostasis.

The yeast homolog of H < beta > 58, a mouse gene essential for embryogenesis, performs a role in the delivery of proteins to the vacuole

The highly conserved and ubiquitously expressed mouse gene H < beta > 58, identified through insertional mutagenesis, has been shown to be essential for early postimplantation development in mouse, but the mechanism by which it acts is unknown (Radice et al. 1991; Lee et al. 1992). We report here the identification of a yeast gene related to the H < beta > 58 gene and provide biochemical and genetic evidence for its function within the cell. The gene, PEP8, plays a role in the delivery of proteins to the vacuole. Disruption of the gene did not affect cell viability. However, the disruptants were shown to have a defect in the processing of the soluble vacuolar proteases but not the membrane vacuolar hydrolases. The processing defect appeared to be a consequence of the inability of the soluble vacuolar hydrolase to reach the vacuole. Although a small amount of the vacuolar precursors was mis-sorted to the extracellular medium, mis-sorting did not appear to be the primary defect in these cells. Pep8p was identified by epitope tagging of the protein. Biochemical fractionation indicated that the protein was peripherally bound to membranes. Immuno-gold electron microscopy indicated that the Pep8p localized to vacuolar membranes. Complementation experiments with the mouse H < beta > 58 cDNA revealed that a Pep8p-H < beta > 58 fusion protein in which the carboxy-terminal 85 amino acids of Pep8p were replaced by the carboxy-terminal 115 amino acids of H < beta > 58 was functional.(ABSTRACT TRUNCATED AT 250 WORDS)

STV1 gene encodes functional homologue of 95-kDa yeast vacuolar H(+)-ATPase subunit Vph1p

The Saccharomyces cerevisiae gene, VPH1 (Vacuolar pH 1), encodes a 95-kDa integral membrane subunit of the vacuolar-type H(+)-ATPase (V-ATPase) that is required for enzyme assembly; disruption of the VPH1 gene impairs vacuolar acidification (Manolson, M.F., Proteau, D., Preston, R. A., Stenbit, A., Roberts, B. T., Hoyt, M. A., Preuss, D., Mulholland, J., Botstein, D., and Jones, E. W. (1992) J. Biol. Chem. 267, 14294-14303). Here we show that STV1 (Similar To VPH1) encodes an integral membrane polypeptide of 102 kDa with 54% identity with the peptide sequence of Vph1p. High copy expression of STV1 partially restores vacuolar acidification in a delta vph1 mutant strain; solubilization and fractionation of membrane proteins from these vacuoles show that Stv1p co-purifies with bafilomycin A1-sensitive ATPase activity and with the 60- and 69-kDa V-ATPase subunits. Immunofluorescence microscopy of strains bearing a single copy of epitope-tagged STV1 reveals punctate staining of the cytoplasm; overexpression of epitope-tagged Stv1p reveals both punctate cytoplasmic staining and vacuolar membrane staining. Northern analysis shows that disruption of STV1 does not affect the level of transcription of VPH1 and that disruption of VPH1 does not affect the level of transcription of STV1. Strains bearing disruption of genes encoding other V-ATPase subunits (VMA1, VMA2, VMA3, and VMA4) fail to grow on media supplemented with 100 mM CaCl2 or 4 mM ZnCl2, media buffered to pH 7.5, or media with a glycerol carbon source. On the same types of media only a delta vph1 delta stv1 double disruption mutant has growth phenotypes equivalent to strains bearing a single disruption of the VMA1, VMA2, VMA3, and VMA4 genes; a delta vph1 strain has only moderate growth inhibition while a delta stv1 strain has wild type growth on the conditions listed above. We conclude that Stv1p is a functional homologue of Vph1p and suggest that Stv1p and Vph1p may be equivalent subunits for V-ATPases located on different organelles. The function of these 100-kDa homologues may be to target or regulate other common V-ATPase subunits for two distinct cellular locations.

Mitochondrial mutation commonly associated with Leber's hereditary optic neuropathy observed in a patient with Wolfram syndrome (DIDMOAD)

DIDMOAD is usually considered an autosomal recessive condition, with wide phenotypic variation, but the possibility of mitochondrial mutations occurring in this condition has been considered. A 19 year old man presented with long standing diabetes mellitus, optic atrophy, and grand mal seizures. Further investigations showed unilateral sensorineural hearing loss and the most common mitochondrial DNA mutation associated with Leber's hereditary optic neuropathy, which was inherited from his mother. This suggests the DIDMOAD phenotype is a mitochondrial disorder in some cases and is likely to have a heterogeneous aetiology.

Desmoplastic malignant melanoma. An immunocytochemical study of 25 cases

Using a panel of seven cell markers, we studied the value of immunocytochemical labelling in the histological diagnosis of desmoplastic malignant melanoma. Sections from routine formalin-fixed tissue of 45 surgical specimens were obtained from 25 cases of malignant melanoma that showed well-marked desmoplastic or neurotropic features. Routinely stained sections (Haematoxylin- and -eosin and melanin stains) were compared with the following panel of seven antibodies: S-100, neuron-specific enolase (NSE), vimentin, factor XIIIa (FXIIIa), desmin and the newer, supposedly more specific antimelanoma antibodies HMB45 and NKIC3. S-100 and NSE were the most sensitive antibodies for desmoplastic malignant melanoma with strong labelling of spindle cells in most cases. In contrast, results for NKIC3 were more variable; results were negative in nearly half the tumours, but strong labelling was seen in six cases (27%). Positive labelling for HMB45 was noted in five tumours (22%); it was mostly confined to small groups of cells in the superficial part of the lesions. Tumour spindle cells were negative for FXIIIa in all cases; there was no increase in the number of positive dermal dendritic cells compared to conventional and spindle cell melanoma. All tumours were desmin-negative, but most were vimentin-positive. Our findings indicate that immunocytochemistry is of less value in the diagnosis of desmoplastic malignant melanoma that it is with other types of malignant melanoma. However, positive or negative labelling for S-100 protein and NSE is useful for suggesting or excluding a diagnosis of desmoplastic malignant melanoma; neither marker is specific and, in particular, positive labelling is also found in most neurofibromas and benign cellular naevi.(ABSTRACT TRUNCATED AT 250 WORDS)

Desmoplastic malignant melanoma: a clinicopathological study of 25 cases

Sixteen cases of malignant melanoma which showed prominent desmoplastic and/or neurotropic features occurring throughout the tumour were compiled from the St John's Dermatology Centre histopathological archives. A further nine melanomas in which both conventional and desmoplastic melanoma were present concomitantly were also studied (three tumours with 66% desmoplastic change, two with 50%, and four with less than 50%). There were 14 males and 11 females, with a mean age of 64 years (range 39-86). The mean interval between presentation and diagnosis was 8 months. Eighteen of the 25 tumours were located on the head and neck, three were on the trunk, one was on the upper limb and three were on the lower limb. Histological review revealed 21 of 25 tumours with overlying atypical lentiginous hyperplasia, lentigo maligna melanoma, or superficial spreading malignant melanoma. Neurotropism was present in nine tumours, with the changes confined to local recurrences in two instances; neuroid differentiation was present in four tumours, and neural and perineural tumour spread was present in four tumours. The depth of invasion exceeded 6 mm in seven tumours, and was 2-6 mm in 16, and less than 2 mm in two. Eighteen of the 25 tumours were incompletely excised at the time of the first excision. Lymphoid aggregates were present in 16 tumours, but in most cases were limited to a few lymphoid foci. Melanin was identified in the dermal component of only five tumours, but not in areas showing typical histological features of desmoplastic malignant melanoma. Treatment was by surgical excision in all cases, and was preceded by radiotherapy in one case. Details of follow-up were obtained in all cases, and the duration ranged from 9 months to 10 years (mean, 3 years 11 months). Eleven patients had died; nine from melanoma and two from other causes. One patient was alive, with deep, inoperable local recurrence. Thirteen patients were alive and clinically free from tumour, including two patients in whom there had been local recurrence. A lower rate of neurotropism was present in the nine patients with partial desmoplastic change compared with those with desmoplasic change throughout the tumour, and represented the only significant difference between the two groups of patients.

Phenotypic analysis of proteinase A mutants. Implications for autoactivation and the maturation pathway of the vacuolar hydrolases of Saccharomyces cerevisiae

We have isolated a number of mutants deficient in activity of the vacuolar hydrolase proteinase A (PrA). The mutations were sequenced and although they all map in the PEP4 gene, which encodes the precursor to PrA, three distinguishable phenotypes have surfaced. The properties of the pep4-7 missense mutant suggested that the activation of the precursor to proteinase A is due to an autocatalytic cleavage. PrA active site mutations were constructed and resulted in accumulation of PrA antigen in the inactive precursor form. Although protease B (PrB), another vacuolar hydrolase, is not required for the production of active PrA, the active form of PrA that accumulates in a strain lacking PrB is larger than that found in a strain containing active PrB. We have purified this larger form of PrA and determined that it bears 7 additional amino acids at its NH2 terminus. It has become apparent from all the studies performed on the maturation pathway of the vacuolar hydrolases that there is a great deal of redundancy built into the system.

The VPH2 gene encodes a 25 kDa protein required for activity of the yeast vacuolar H(+)-ATPase

Strains bearing the vph2 mutation are defective in vacuolar acidification. The VPH2 gene was isolated from a genomic DNA library by complementation of the zinc-sensitive phenotype of the mutant. Deletion analysis localized the complementing activity to a 1.2 kb DNA fragment. Sequence analysis of this fragment revealed the presence of a single open reading frame that encoded a protein of 215 amino acids. Computer analysis indicated that the protein, which has a predicted molecular mass of 25,286 Daltons, has two distinct membrane-spanning domains. Biochemical studies indicated that strains bearing the vph2 mutation have greatly reduced levels of vacuolar proton pumping and ATPase activity and that the nucleotide binding subunits of the multimeric vacuolar H(+)-ATPase failed to be correctly targeted to the vacuolar membrane. The vph2 mutant fails to grow on YEP glycerol medium and on media containing 100 mM-CaCl2 or 4 mM-ZnCl2 or buffered to pH 7.5, a phenotype observed in strains carrying deletions in the genes encoding several vacuolar H(+)-ATPase subunits. The VPH2 gene is identical to the VMA12 gene (T. Stevens and Y. Anraku, personal communication).

The quality and relevance of peripheral neuropathy data on a diabetic clinical information system

Routinely collected peripheral neuropathy data entered on a diabetic clinical information system since 1979 have been audited for completeness, consistency, accuracy (inter-observer variation), validity by comparison with biothesiometry, and relevance by life table analysis for foot ulceration. Peripheral neuropathy was defined by a neuropathy disability score > or = 4. The data were 98% complete. Forty-nine of 3405 (1.4%) had inconsistent records. Agreement between observers for clinical examination was significant (p < 0.05) for aggregate neuropathy score and its individual components except the knee jerk: Kappa score for observer variation for neuropathy score 0.56 (95% confidence interval 0.36-0.76). There was good agreement between neuropathy defined as aggregate score > or = 4, and as combined vibration perception thresholds for both feet > 60 V: Kappa statistic 0.62 (95% confidence interval 0.44-0.80). The chance of developing a foot problem in 3 years increased from 3% for patients with a score of zero to 45% for people with a score of between 9 and 12. We conclude that the calculation of a clinical neuropathy score is a simple, valid and relevant method for diabetes care both in hospital and the community. When combined with palpation of peripheral pulses most patients at risk of foot ulceration can be identified allowing targeting of preventive chiropody and orthotic resources.

Evidence for a conserved 95-120 kDa subunit associated with and essential for activity of V-ATPases

Vacuoles purified from Saccharomyces cerevisiae bearing the vph1-1 mutation had no detectable bafilomycin-sensitive ATPase activity or ATP-dependent proton pumping. Furthermore, the vacuolar H(+)-ATPase (V-ATPase) nucleotide binding subunits were no longer associated with vacuolar membranes yet were present at wild-type levels in yeast whole-cell extracts. The VPH1 gene was cloned by screening a lambda gt11 expression library with antibodies directed against a 95 kDa vacuolar integral membrane protein and independently cloned by complementation of the vph1-1 mutation. Deletion disruption of the VPH1 gene revealed that the VPH1 gene is required for vacuolar H(+)-ATPase assembly and vacuolar acidification but is not essential for cell viability or for targeting and maturation of vacuolar proteases. VPH1 encodes a predicted polypeptide of 840 amino acid residues (95.6 kDa) with putative membrane-spanning regions. Cell fractionation and immunodetection demonstrate that Vph1p is a vacuolar integral membrane protein that co-purifies with V-ATPase activity. Vph1p has 42% identity to the 116 kDa polypeptide of the rat clathrin-coated vesicles/synaptic vesicle proton pump, 42% identity to the TJ6 mouse immune suppressor factor, 42% identity to the Caenorhabditis elegans proton pump homologue and 54% identity to the predicted polypeptide encoded by the yeast gene STV1 (Similar To VPH1, identified as an open reading frame next to the BUB2 gene.

Intravascular spread of keratoacanthoma. An alarming but benign phenomenon

We report a patient with a keratoacanthoma of the scalp in which there was invasion of several medium-sized vessels by the tumour at a distance from the main lesion. A marked inflammatory response within the invaded vessels as well as a benign clinical course do not suggest that this phenomenon represents malignant transformation.

The VPH1 gene encodes a 95-kDa integral membrane polypeptide required for in vivo assembly and activity of the yeast vacuolar H(+)-ATPase

Yeast vacuolar acidification-defective (vph) mutants were identified using the pH-sensitive fluorescence of 6-carboxyfluorescein diacetate (Preston, R. A., Murphy, R. F., and Jones, E. W. (1989) Proc. Natl. Acad. Sci. U.S.A. 86, 7027-7031). Vacuoles purified from yeast bearing the vph1-1 mutation had no detectable bafilomycin-sensitive ATPase activity or ATP-dependent proton pumping. The peripherally bound nucleotide-binding subunits of the vacuolar H(+)-ATPase (60 and 69 kDa) were no longer associated with vacuolar membranes yet were present in wild type levels in yeast whole cell extracts. The VPH1 gene was cloned by complementation of the vph1-1 mutation and independently cloned by screening a lambda gt11 expression library with antibodies directed against a 95-kDa vacuolar integral membrane protein. Deletion disruption of the VPH1 gene revealed that the VPH1 gene is not essential for viability but is required for vacuolar H(+)-ATPase assembly and vacuolar acidification. VPH1 encodes a predicted polypeptide of 840 amino acid residues (molecular mass 95.6 kDa) and contains six putative membrane-spanning regions. Cell fractionation and immunodetection demonstrate that Vph1p is a vacuolar integral membrane protein that co-purifies with vacuolar H(+)-ATPase activity. Multiple sequence alignments show extensive homology over the entire lengths of the following four polypeptides: Vph1p, the 116-kDa polypeptide of the rat clathrin-coated vesicles/synaptic vesicle proton pump, the predicted polypeptide encoded by the yeast gene STV1 (Similar To VPH1, identified as an open reading frame next to the BUB2 gene), and the TJ6 mouse immune suppressor factor.

Genes required for vacuolar acidity in Saccharomyces cerevisiae

Mutations that cause loss of acidity in the vacuole (lysosome) of Saccharomyces cerevisiae were identified by screening colonies labeled with the fluorescent, pH-sensitive, vacuolar labeling agent, 6-carboxyfluorescein. Thirty nine vacuolar pH (Vph-) mutants were identified. Four of these contained mutant alleles of the previously described PEP3, PEP5, PEP6 and PEP7 genes. The remaining mutants defined eight complementation groups of vph mutations. No alleles of the VAT2 or TFP1 genes (known to encode subunits of the vacuolar H(+)-ATPase) were identified in the Vph- screen. Strains bearing mutations in any of six of the VPH genes failed to grow on medium buffered at neutral pH; otherwise, none of the vph mutations caused notable growth inhibition on standard yeast media. Expression of the vacuolar protease, carboxypeptidase Y, was defective in strains bearing vph4 mutations but was apparently normal in strains bearing any of the other vph mutations. Defects in vacuolar morphology at the light microscope level were evident in all Vph- mutants. Strains that contained representative mutant alleles of the 17 previously described PEP genes were assayed for vacuolar pH; mutations in seven of the PEP genes (including PEP3, PEP5, PEP6 and PEP7) caused loss of vacuolar acidity.

N-linked glycosylation of proteinase B precursors of the yeast Saccharomyces cerevisiae is not required for proper targeting or processing of the enzyme

Proteinase B precursors are modified by an N-linked carbohydrate side chain at Asn 314. Glycosylation at this position is not required for proper localization, processing, or activation of the enzyme.

Activation of the proteinase B precursor of the yeast Saccharomyces cerevisiae by autocatalysis and by an internal sequence

Proteinase B (PrB) is a subtilisin-like serine protease found in the vacuole of the yeast Saccharomyces cerevisiae. It is first made as a large precursor that consists of a putative signal sequence, a 260-amino acid pro region, the serine protease domain, and two small COOH-terminal post regions (Moehle, C. M., Dixon, C. K., and Jones, E. W. (1989) J. Cell Biol. 108, 309-324). This precursor is glycosylated and proteolytically processed at least three times before mature enzyme is formed. To determine whether an intact PrB catalytic site is required for proteolytic processing of the precursor, point mutations were generated at the codons for the active site serine or aspartate residues by site-directed mutagenesis. The effect of these mutations on PrB processing suggests that the large pro region may be cleaved by an intramolecular, autocatalytic mechanism. The properties of a prb1 mutant that accumulates a 37-kDa precursor in addition to mature sized mutant PrB antigen suggests that the final proteolytic cleavage step is also autocatalytic. A prb1 deletion that lacks codons for the large pro region was made to test whether this part of the precursor is required for formation of mature PrB. Analysis of this mutant revealed two functions for this region: it prevents N-linked glycosylation of the serine protease domain and it allows the PrB precursor to be processed by proteinase A. The pro region can fulfill this latter function if added as a separate molecule, so long as glycosylation of the catalytic domain is prevented by other means.

Isolation and characterization of PEP3, a gene required for vacuolar biogenesis in Saccharomyces cerevisiae

The Saccharomyces cerevisiae PEP3 gene was cloned from a wild-type genomic library by complementation of the carboxypeptidase Y deficiency in a pep3-12 strain. Subclone complementation results localized the PEP3 gene to a 3.8-kb DNA fragment. The DNA sequence of the fragment was determined; a 2,754-bp open reading frame predicts that the PEP3 gene product is a hydrophilic, 107-kDa protein that has no significant similarity to any known protein. The PEP3 predicted protein has a zinc finger (CX2CX13CX2C) near its C terminus that has spacing and slight sequence similarity to the adenovirus E1a zinc finger. A radiolabeled PEP3 DNA probe hybridized to an RNA transcript of 3.1 kb in extracts of log-phase and diauxic lag-phase cells. Cells bearing pep3 deletion/disruption alleles were viable, had decreased levels of protease A, protease B, and carboxypeptidase Y antigens, had decreased repressible alkaline phosphatase activity, and contained very few normal vacuolelike organelles by fluorescence microscopy and electron microscopy but had an abundance of extremely small vesicles that stained with carboxyfluorescein diacetate, were severely inhibited for growth at 37 degrees C, and were incapable of sporulating (as homozygotes). Fractionation of cells expressing a bifunctional PEP3::SUC2 fusion protein indicated that the PEP3 gene product is present at low abundance in both log-phase and stationary cells and is a vacuolar peripheral membrane protein. Sequence identity established that PEP3 and VPS18 (J. S. Robinson, T. R. Graham, and S. D. Emr, Mol. Cell. Biol. 11:5813-5824, 1991) are the same gene.

White fibrous papulosis of the neck

We report a case of white fibrous papulosis of the neck in a 70-year-old Iranian woman. To date this recently reported entity has only been described in Japanese patients. This asymptomatic eruption characteristically affects the posterior neck. The pale papules are round to oval 2-3 mm in diameter, and not follicular. Histology shows thickened collagen bundles in the superficial and mid-dermis with a normal elastic pattern.