Effectiveness of cladribine therapy in patients with pulmonary Langerhans cell histiocytosis.

BackgroundPulmonary Langerhans cell histiocytosis (PLCH) is a rare disorder characterised by granulomatous proliferation of CD1a-positive histiocytes forming granulomas within lung parenchyma, in strong association with tobacco smoking, and which may result in chronic respiratory failure. Smoking cessation is considered to be critical in management, but has variable effects on outcome. No drug therapy has been validated. Cladribine (chlorodeoxyadenosine, 2-CDA) down-regulates histiocyte proliferation and has been successful in curbing multi-system Langerhans cell histiocytosis and isolated PLCH.Methods and patientsWe retrospectively studied 5 patients (aged 37¿55 years, 3 females) with PLCH who received 3 to 4 courses of cladribine therapy as a single agent (0.1 mg/kg per day for 5 consecutive days at monthly intervals). One patient was treated twice because of relapse at 1 year. Progressive pulmonary disease with obstructive ventilatory pattern despite smoking cessation and/or corticosteroid therapy were indications for treatment. Patients were administered oral trimethoprim/sulfamethoxazole and valaciclovir to prevent opportunistic infections. They gave written consent to receive off-label cladribine in the absence of validated treatment.ResultsFunctional class dyspnea improved with cladribine therapy in 4 out of 5 cases, and forced expiratory volume in 1 second (FEV1) increased in all cases by a mean of 387 ml (100¿920 ml), contrasting with a steady decline prior to treatment. Chest high-resolution computed tomography (HRCT) features improved with cladribine therapy in 4 patients. Hemodynamic improvement was observed in 1 patient with pre-capillary pulmonary hypertension. The results suggested a greater treatment effect in subjects with nodular lung lesions and/or thick-walled cysts on chest HRCT, with diffuse hypermetabolism of lung lesions on positron emission tomography (PET)-scan, and with progressive disease despite smoking cessation. Infectious pneumonia developed in 1 patient, with later grade 4 neutrocytopenia but without infection.DiscussionData interpretation was limited by the retrospective, uncontrolled study design and small sample size.ConclusionCladribine as a single agent may be effective therapy in patients with progressive PLCH.

Model structure of human APOBEC3G.

BACKGROUND: APOBEC3G (apolipoprotein B mRNA-editing enzyme, catalytic polypeptide-like 3G) has antiretroviral activity associated with the hypermutation of viral DNA through cytosine deamination. APOBEC3G has two cytosine deaminase (CDA) domains; the catalytically inactive amino-terminal domain of APOBEC3G (N-CDA) carries the Vif interaction domain. There is no 3-D structure of APOBEC3G solved by X-ray or nuclear magnetic resonance. METHODOLOGY/PRINCIPAL FINDINGS: We predicted the structure of human APOBEC3G based on the crystal structure of APOBEC2. To assess the model structure, we evaluated 48 mutants of APOBEC3G N-CDA that identify novel variants altering DeltaVif HIV-1 infectivity and packaging of APOBEC3G. Results indicated that the key residue D128 is exposed at the surface of the model, with a negative local electrostatic potential. Mutation D128K changes the sign of that local potential. In addition, two novel functionally relevant residues that result in defective APOBEC3G encapsidation, R122 and W127, cluster at the surface. CONCLUSIONS/SIGNIFICANCE: The structure model identifies a cluster of residues important for packaging of APOBEC3G into virions, and may serve to guide functional analysis of APOBEC3G.

On the role of kerato-epithelin in the pathogenesis of 5q31-linked corneal dystrophies.

PURPOSE: Recently, the authors identified a gene, BIGH3, in which different mutations cause a group of hereditary corneal dystrophies: lattice type I and IIIA (CDLI and CDLIIIA), granular Groenouw type I (CDGGI), Avellino (CDA), and Reis-Bücklers' (CDRB). All these disorders are characterized by the progressive accumulation of corneal deposits with different structural organization. Experiments were conducted to determine the role of kerato-epithelin (KE), the product of BIGH3, in the pathogenesis of the diseases. METHODS: KE-15 and KE-2, two rabbit antisera raised against peptides from the 69-364 and 426 - 682 amino acid regions of KE respectively, were used for immunohistology of the corneas obtained after keratoplasty in six CDLI patients, three CDGGI patients, and one CDA patient. RESULTS: The nonamyloid deposits observed in CDGGI stained intensively with KE-15 and KE-2, whereas the amyloid deposits in all analyzed CDLI corneas reacted to KE-2 but not to KE-15. In the CDA cornea, where amyloid and nonamyloid inclusions were present, positive staining with both antisera was observed. CONCLUSIONS: Pathologic amyloid and nonamyloid deposits observed in CDLI, CDGGI-, and CDA-affected corneas are caused by KE accumulation. Different staining patterns of amyloid and nonamyloid deposits observed with antibodies against the amino and carboxyl termini of KE suggest that two mechanisms of KE misfolding are implicated in the pathogenesis of 5q31-linked corneal dystrophies.

Fate of cadmium in rat renal tubules: a micropuncture study.

Free-flow micropuncture was carried out in superficial nephrons of Munich-Wistar type rats infused acutely with Cd acetate (CdA) or Cd-DTPA (141 microM Cd). Fluid obtained from Bowman's space (BS) or end-proximal tubule sites was analyzed for Cd and inulin. The fluid/plasma Cd concentration ratio in BS averaged 0.2 and 1.0 during CdA and Cd-DTPA infusions, respectively. End-proximal tubule fractional excretion of Cd during CdA infusion averaged 0.34. Previous administration of CdA (1.0 mg/kg, 48 hr before micropuncture) increased the level of circulating Cd-metallothioneins, as measured by radioimmunoassay, but did not affect the luminal tubular uptake of Cd during CdA infusion. No net transepithelial movement of Cd-DTPA was measured. It is concluded that Cd ultrafiltered during inorganic Cd administration is taken up to a large extent by the convoluted part of proximal tubules.