Millennium fat-cell lipolysis reveals unsuspected novel tracks

Adipose tissue lipolysis, i.e., the catabolic process leading to the breakdown of triglycerides into fatty acids and glycerol, is often considered as a simple and well-understood metabolic pathway. However, progress on the hormonal regulation and molecular mechanism of fat-cell lipolysis is opening new avenues and points to a number of unanswered questions. Recent studies on the lipolytic beta- and antilipolytic alpha2-adrenergic control of lipolysis has allowed a better understanding of the relative contribution of the two types of receptors and provide strong evidence for the in vivo implication of alpha2-adrenoceptors in the physiological control of subcutaneous adipose-tissue lipolysis. A novel lipolytic system has been characterized in human fat cells. Natriuretic peptides stimulate lipolysis through a cGMP-dependent pathway. The molecular details of the lipolytic reaction are not fully understood. Translocation of hormone-sensitive lipase, the rate-limiting enzyme of lipolysis, to the lipid droplet seems to be an important step during lipolytic activation. Reorganization of the lipid droplet coating by perilipins may also facilitate the access of the enzyme. Unexpectedly, hormone-sensitive lipase-deficient mice are not obese and show residual adipose-tissue lipolysis, which suggests the existence of another triglyceride lipase. Whether the expression of this uncharacterized neutral lipase is compensatory for the lack of hormone-sensitive lipase is an important question yet to be resolved. In humans, alterations of hormone-sensitive lipase expression are associated with changes in lipolysis in various physiological and pathological states. Genetic studies show that beta2-adrenoceptor and hormone-sensitive lipase genes may participate in the polygenic background of obesity.

Postmortem histological survey of the ocular lesions in a British population of AIDS patients

AIMS

To study ocular pathology and systemic correlations in a series of 73 postmortem eyes from British patients who died from AIDS before the introduction of a HAART regimen.

METHODS

The eyes were studied with conventional histology, special histochemical stainings, and immunohistochemistry.

RESULTS

72.6% of the cases showed chronic uveal inflammation, caused by opportunistic agents in 37.7% of them (cytomegalovirus (CMV) in 30.1%, C neoformans in 5.6%, and Gram positive bacteria in 1.8%). Cytoid bodies were noted in 10/73 eyes, three linked to CMV retinitis. Six retinal haemorrhages, four of which were secondary to CMV, were found. 14 specimens (19. 1%) showed foci of calcification, and a further 11 (15%) calcium oxalate deposits. In no cases were the calcific deposits suspected clinically. Six eyes (8.2%) did not show any abnormality.

CONCLUSIONS

CMV retinitis is the most common (28.7%, 21/73) ocular infection in this series and may occur either during or in the absence of systemic dissemination. Conversely, ocular cryptococcosis appears to be an epiphenomenon of systemic and CNS disease. No other opportunistic ocular infections were present in this series. Interesting findings were the presence of intraocular precipitates of calcium oxalate and calcium phosphate or carbonate in a significant number of cases (15% and 19%, respectively), and the high prevalence of idiopathic uveal inflammation (43.8%).

Prospective study of the usefulness of sural nerve biopsy

OBJECTIVE

This study aimed to determine the usefulness of sural nerve biopsy in neurological practice.

METHODS

The first prospective study of sural nerve biopsy in 50 consecutive patients was undertaken. The investigating neurologist declared the prebiopsy diagnosis and management plan and after 3 months an independent neurologist evaluated the contribution of the biopsy to diagnosis and management. An independent audit officer sought information from the patient about the adverse effects and value of the biopsy after 6 weeks and 6 months.

RESULTS

In seven cases the nerve biopsy changed the diagnosis, in 35 cases the biopsy confirmed the suspected diagnosis, and in eight cases the biopsy was non-contributory. The biopsy either changed or was helpful in guiding patient management in 60%, especially those with demyelinating neuropathy and multiple mononeuropathy. Seven patients reported having had infection and 10 reported increased pain at the biopsy site 6 months later.

CONCLUSION

In a consecutive series of 50 cases, sural nerve biopsy altered the diagnosis in 14%, affected management in 60%, and caused persistent increased pain at the biopsy site in 33%.

Magnetic resonance imaging of the normal and diseased feline middle ear

The magnetic resonance imaging appearance of the feline middle ear is described in three healthy cats and in five cats with middle ear disease. Owing to the good spatial resolution, multiplanar slice orientation as well as display high contrast resolution of soft tissue, in particular fluids, MR imaging was helpful prior to surgery. It is superior to radiography which failed to allow identification of the abnormality in two of our five cats. MR imaging for middle ear disease should include dorsal and transverse plane images using T1- and T2-weighted sequences. In the presence of a mass within the bulla or the external ear canal application of contrast medium is helpful.

MAGE-B5, MAGE-B6, MAGE-C2, and MAGE-C3: four new members of the MAGE family with tumor-specific expression

A number of genes of the MAGE-A, B, and C families have been shown to code for antigens that are recognized on many human tumors by autologous cytolytic T lymphocytes. These antigens ought to be strictly tumor specific because the encoding MAGE genes are not expressed in normal adult cells except for male germline cells, which lack HLA expression. To identify new genes of this type, we performed representational difference analysis on a melanoma cell line by subtraction with a normal skin sample. This led to the identification of MAGE-C2, a new member of the MAGE-C family. A search for nucleotide sequences encoding MAGE-like proteins in public databases led to the identification of three additional MAGE genes, which were named MAGE-B5, MAGE-B6, and MAGE-C3. The four new MAGE genes are not expressed in normal tissues, except for testis, and are expressed in tumors of different histological origins. Therefore, like other MAGE genes expressed specifically in tumors, MAGE-B5, MAGE-B6, MAGE-C2, and MAGE-C3 ought to encode antigens that could be targets for cancer immunotherapy.

MAGE-B5, MAGE-B6, MAGE-C2, and MAGE-C3: four new members of the MAGE family with tumor-specific expression

A number of genes of the MAGE-A, B, and C families have been shown to code for antigens that are recognized on many human tumors by autologous cytolytic T lymphocytes. These antigens ought to be strictly tumor specific because the encoding MAGE genes are not expressed in normal adult cells except for male germline cells, which lack HLA expression. To identify new genes of this type, we performed representational difference analysis on a melanoma cell line by subtraction with a normal skin sample. This led to the identification of MAGE-C2, a new member of the MAGE-C family. A search for nucleotide sequences encoding MAGE-like proteins in public databases led to the identification of three additional MAGE genes, which were named MAGE-B5, MAGE-B6, and MAGE-C3. The four new MAGE genes are not expressed in normal tissues, except for testis, and are expressed in tumors of different histological origins. Therefore, like other MAGE genes expressed specifically in tumors, MAGE-B5, MAGE-B6, MAGE-C2, and MAGE-C3 ought to encode antigens that could be targets for cancer immunotherapy.

Cellular localisation of HHV-8 in Castleman's disease: is there a link with lymph node vascularity?

AIMS

Human herpesvirus 8 (HHV-8) has been identified in multicentric Castleman's disease and in angioimmunoblastic lymphadenopathies. However, the presence of the virus does not necessarily indicate an aetiological role in these conditions. This study investigates the cell types infected by HHV-8 in Castleman's disease and examines the correlation between HHV-8 and Castleman's disease lymph node angiogenesis.

METHODS

Sixteen formalin fixed, paraffin wax embedded samples from patients with Castleman's disease (six multicentric, 10 solitary) were examined for the presence of HHV-8 using the polymerase chain reaction (PCR), non-isotopic in situ hybridisation, PCR in situ hybridisation (PCR-ISH), and real time quantitative TaqMan PCR to HHV-8 open reading frame 26 (ORF-26), and viral (v)-cyclin encoding regions. Vascularity was assessed using CD34, CD31, and factor VIII immunocytochemistry, and lymph nodes were scored as "low" or "high".

RESULTS

Five multicentric Castleman's disease and two solitary Castleman's disease biopsies were positive for HHV-8. HHV-8 was identified in approximately 10% of intranodal B lymphocytes, in endothelial cells, and in subcapsular spindle cell proliferations. The copy number of HHV-8 was low at 10-50 copies/1000 cells. The highest copy number was in subcapsular spindle cells. There was no correlation between vascularity score and HHV-8 status.

CONCLUSION

The preferential localisation of HHV-8 in subcapsular spindle cell proliferations (where early intranodal Kaposi's sarcoma initiates) and endothelial cells in Castleman's disease might finally explain the link between intranodal Kaposi's sarcoma and Castleman's disease.

The use of HPLC for the detection and quantification of formaldehyde in the pteridophyta

Formaldehyde, as its dimedone adduct, formaldemethone, has been detected and quantified in all species of Pteridophyta examined. The procedure involved the use of an Hypersil C-18 column, methanol-water (60 : 40 v/v) as the mobile phase and an UV detector set at 258 nm. Quantification was based on peak height. Yields varied from 30 microg/g fresh weight for Polystichum setiferum to 5370 microg/g fresh weight for Selaginella viticulosa.

Effects of a centipede venom fraction on insect nervous system, a native Xenopus oocyte receptor and on an expressed Drosophila muscarinic receptor

Centipede venoms are complex protein mixtures; very few is known about their pharmacological actions. Application of a Scolopendra sp. venom fraction (SC1) on the cockroach giant axon induced an increase in the leak current correlated with a decrease in the membrane resistance, suggesting the presence in SC1 of components opening non-specific pores in the axonal membrane. On a cockroach central cholinergic synapse, microinjection of SC1 induced a small transient depolarization of the postsynaptic membrane, followed by a slow stable depolarization and a drastic decrease in the evoked subthreshold excitatory postsynaptic potential amplitude. A pretreatment of the ganglion with atropine or scopolamine reduced the amplitude of the SC1-induced depolarizing wave, suggesting a possible cholinergic muscarinic target. On control Xenopus oocytes, SC1 induced an inward oscillatory Ca2(+)-dependent Cl- current mediated through the activation of native lysophosphatidic acid receptors (LPAr). Indeed, pretreatment of oocytes with 1 microM N-palmitoyl-tyrosine phosphoric acid, a selective competitive antagonist of LPAr, decreased responses to SC1 by 70%. Application of SC1 to oocytes expressing a cloned Drosophila muscarinic receptor (Dml) induced a biphasic response comprising: (1) a large fast Cl- current that was abolished by pretreatment with atropine and scopolamine and (2) a slow and small oscillating Cl- current corresponding to the response observed in control oocytes. These observations confirm the presence of muscarinic agonists in SCI and reveal their direct action on an insect muscarinic receptor subtype homologous to mammalian M1-M3 receptors.

Vasculitic neuropathy in association with chronic graft-versus-host disease

A 43-year-old woman is reported who developed acute and later chronic graft-versus-host disease following an unrelated donor bone marrow transplantation for chronic myeloid leukaemia. Four years later, she developed a sensory multiple mononeuropathy with biopsy features of chronic vasculitis. This is the first report of vasculitic neuropathy in association with graft-versus-host disease.

Brittle diabetes characterised by recurrent hypoglycaemia

There is little information on the clinical characteristics of "brittle" Type 1 (insulin-dependent) diabetic patients with predominantly hypoglycaemic instability. From a total cohort of 381 brittle diabetic patients from various parts of the United Kingdom, 64 (17%) had life-disrupting instability due to recurrent hospital admissions with hypoglycaemia. Compared to brittle patients with recurrent ketoacidosis (DKA), who comprised 59% of the total, those with recurrent hypoglycaemia were characterised by older mean age (34 +/- 20 v 22 +/- 11 y, p < 0.001), and more equal sex distribution (53% v 71% female, p < 0.05). Patients with "mixed brittleness" (24% of total) were intermediate between the other groups, in terms of both age and female predominance. Physicians in charge of patients with hypoglycaemic brittle diabetes considered psychosocial factors to be frequent underlying causes, though organic conditions such as lost hypoglycaemic warnings and alcohol abuse were also mentioned. Factitious insulin overdose was diagnosed in 3 patients. We conclude that hypoglycaemic brittle diabetes is a small but important sub-group of the overall brittle syndrome. It differs in age and sex distribution from the more common syndrome of recurrent DKA.

Isolation and characterization of pyrimidine auxotrophs, and molecular cloning of the pyrE gene from the hyperthermophilic archaeon Pyrococcus abyssi

Uracil auxotrophic mutants of the hyperthermophilic archaeon Pyrococcus abyssi were isolated by screening for resistance to 5-fluoro-orotic acid (5-FOA). Wild-type strains were unable to grow on medium containing 5-FOA, whereas mutants grew normally. Enzymatic assays of extracts from wild-type P. abyssi and from pyrimidine auxotrophs demonstrated that the mutants are deficient in orotate phosphoribosyltransferase (PyrE) and/or orotidine-5'-monophosphate decarboxylase (PyrF) activity. The pyrE gene of wild-type P. abyssi and one of its mutant derivatives were cloned and sequenced. This pyrE gene could serve as selectable marker for the development of gene manipulation systems in archaeal hyperthermophiles.

A new MAGE gene with ubiquitous expression does not code for known MAGE antigens recognized by T cells

A number of genes of the MAGE family have been shown to code for antigens that are recognized on many human tumors by autologous CTLs. These antigens should be strictly tumor specific because the encoding MAGE genes are not expressed in normal adult cells, except for male germ-line cells, which lack HLA expression. Here, we report that a distant relative of the previously identified MAGE genes is expressed in many, if not all, normal tissues. This gene, which was named MAGE-D, is located in Xp11. Its exon-intron structure is completely different from that of the other MAGE genes. None of the 20 MAGE antigenic peptides presently known to be recognized by T lymphocytes is encoded by the new MAGE gene. It appears, therefore, that this new finding leaves intact the tumor specificity of the antigens encoded by the MAGE genes that are expressed only in tumor and germ-line cells.

HIV enteropathy: comparative morphometry of the jejunal mucosa of HIV infected patients resident in the United Kingdom and Uganda

AIMS

To compare jejunal mucosal morphometry in HIV infected patients resident in London and Uganda.

PATIENTS

Twenty HIV positive patients from London and 16 from Uganda were studied, and compared with HIV negative control subjects from both sites.

METHODS

Stools and biopsy specimens were examined for enteropathogens. Surface area to volume (S:V) ratio was estimated morphometrically, mean crypt length of jejunal biopsy specimens was measured, and HIV infected cells detected immunohistochemically were quantified.

RESULTS

Enteric pathogens were detected in none of the London patients, and in three Ugandan patients. S:V ratio was lower, and mean crypt length higher, in the specimens of London patients than in normal subjects, but there was no difference in S:V ratio or mean crypt length between Ugandan patients and controls. A negative correlation was present between S:V ratio and mean crypt length in all biopsy specimens analysed. HIV infected cells were detected only in lamina propria.

CONCLUSION

Infection of cells in the lamina propria of the jejunum with HIV stimulates crypt cell proliferation, and a fall in villous surface area. The mucosal response to HIV is masked by other pathogens in the African environment.

Detection of JC virus in two African cases of progressive multifocal leukoencephalopathy including identification of JCV type 3 in a Gambian AIDS patient

Progressive multifocal leukoencephalopathy (PML) is a fatal demyelinating central nervous system (CNS) infection, affecting mainly oligodendrocytes, but also occasional astrocytes. In the USA, Europe and Asia, PML is caused by the human polyomavirus JC virus (JCV) and in autopsy series occurs in about 4-7% of AIDS patients. In Africa, the prevalence of PML in AIDS patients is uncertain and the causative agent is unknown. This study reports immunocytochemical and PCR confirmation of PML in the CNS of an AIDS patient dying in Uganda, East Africa (case 1). In a Gambian patient infected with HIV-2 who died 3 months after onset of AIDS/PML in Germany (case 2), it was possible to confirm the identity of the virus by DNA sequencing of the PCR amplified JCV product. This African genotype of the virus (type 3) showed an unusual re-arrangement of the regulatory region, and could be distinguished at several sites from East African and African-American JCV strains described previously. This study has confirmed that PML is a complication of African AIDS as it is in Europe and the USA, and that JCV type 3 is pathogenic in African AIDS patients. Furthermore, the finding of an African genotype of JCV in a patient dying in Germany suggests that in this individual JCV represented a latent infection acquired in Africa.

LAGE-1, a new gene with tumor specificity

Representational difference analysis was used to identify genes that are expressed in a human melanoma cell line and not in normal skin. A cDNA clone that appeared to be specific for tumors was obtained and the corresponding gene was sequenced. This new gene was named LAGE-I. Using a LAGE-I probe to screen a cDNA library from the same melanoma cell line, we identified a closely related gene, which proved to be identical to NY-ESO-I, a gene recently reported to code for an antigen recognized by autologous antibodies in an esophageal squamous cell carcinoma. Gene LAGE-I maps to Xq28. It comprises 3 exons. Alternative splicing produces 2 major transcripts encoding polypeptides of 210 and 180 residues, respectively. Expression of LAGE-I was observed in 25-50% of tumor samples of melanomas, non-small-cell lung carcinomas, bladder, prostate and head and neck cancers. The only normal tissue that expressed the gene was testis. As for MAGE-AI, expression of LAGE-I is induced by deoxy-azacytidine in lymphoblastoid cells, suggesting that tumoral expression is due to demethylation. The expression of LAGE-I is strongly correlated with that of NY-ESO-I. It is also clearly correlated with the expression of MAGE genes.

[Rejection antigens of tumors and specific immunotherapy of cancer]

Human tumors carry antigens that are recognized by the patients' cytolytic T lymphocytes. An important group of antigens is coded by the MAGE family of genes. These antigens are expressed in a significant proportion of tumors of numerous histological types but not in normal tissues. Clinical trials are underway in an attempt to immunize patients suffering from metastatic melanomas using peptides coded by the MAGE genes. Regressions have been observed in 5 of the 17 immunized patients.