Periodontitis Is Associated with Chronic Obstructive Pulmonary Disease.

Although they are known to share pathophysiological processes, the relationship between periodontitis and chronic obstructive pulmonary disease (COPD) is not fully understood. The aim of the present study was to test the hypothesis that periodontitis is associated with a greater risk of development of COPD, when smoking is taken into account. The analysis in a 5-y follow-up population-based cohort study was based on 900 community-dwelling Japanese adults (age: 68.8 ± 6.3 [mean ± SD], 46.0% male) without COPD aged 60 or older with at least 1 tooth. Participants were classified into 3 categories according to baseline periodontitis severity (no/mild, moderate, and severe). COPD was spirometrically determined by a fixed ratio of <0.7 for forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) and by FEV1/FVC below the lower limit of normal. Poisson regression was used to calculate the relative risk (RR) of developing COPD according to the severity of periodontitis. The population attributable fraction (PAF) was also calculated. During follow-up, 22 (2.4%) subjects developed COPD. Compared with no/mild periodontitis subjects, a significantly increased risk of COPD occurred among severe periodontitis subjects (RR = 3.55; 95% confidence interval [CI], 1.18 to 10.67), but no significant differences were observed between the no/mild and moderate categories (RR = 1.48; 95% CI, 0.56 to 3.90). After adjustment for potential confounders, including smoking intensity, the relationship between severe periodontitis and risk of COPD remained significant (RR = 3.51; 95% CI, 1.15 to 10.74). Likewise, there was a positive association of periodontitis severity with risk of COPD ( P for trend = 0.043). The PAF for COPD due to periodontitis was 22.6%. These data highlight the potential importance of periodontitis as a risk factor for COPD.

Oral mycobiome in community-dwelling elderly and its relation to oral and general health conditions.

OBJECTIVE: Oral fungal infection is generally associated with dysbiosis related to antibiotic use, immunodeficiency, or frailty. However, fungal colonization in a typical population without apparent symptoms and its associated conditions are poorly understood. In this study, oral fungal colonization in community-dwelling and independently living elderly populations was evaluated and factors affecting fungal colonization were analyzed. SUBJECTS AND METHODS: The subjects (410; 181 males and 229 females) were 75-99 years of age; those under prior antibiotic use were excluded. Fungal populations in the saliva were evaluated by PCR-based molecular techniques. Body mass index (BMI), smoking habits, and oral health conditions were examined. RESULTS: Salivary fungal amounts exceeded 104  CFU/ml in 63 (15.4%) of 410 subjects. Candida albicans was most frequently detected (98.4%), followed by Candida glabrata (54.0%), and Candida dubliniensis (38.1%) in those subjects with fungi at 104  CFU/ml or over. Fungi at 104  CFU/ml or over in the presence of C. glabrata or C. dubliniensis was significantly associated with low BMI. CONCLUSIONS: Candida albicans, C. glabrata, and C. dubliniensis dominated the oral mycobiome in Japanese community-dwelling elderly. Lower BMI might signify compromised health status and thus could result in susceptibility to specific candidiasis by C. glabrata and C. dubliniensis.

Prognosis of uveal melanoma based on race in 8100 patients: The 2015 Doyne Lecture.

A retrospective, nonrandomized, interventional case series of 8100 patients with uveal melanoma were evaluated for melanoma-related metastasis based on patient race. The patient race was Caucasian (n=7918, 98%), Hispanic (n=105, 1%), Asian (n=44, <1%), or African American (n=33, <1%). On the basis of race (Caucasian, Hispanic, Asian, and African American), significant differences were noted in mean age at presentation (58, 48, 44, and 52 years; P<0.001), distance of posterior tumor margin to foveola (5, 5, 6, and 4 mm; P<0.001), distance of posterior tumor margin to optic disc (5, 5, 6, and 4 mm) (P<0.001), tumor base (11, 12, 12, and 13 mm; P<0.001), tumor thickness (5.4, 7.1, 6.5, and 7.5 mm; P<0.001), intraocular hemorrhage (10, 14, 11, and 24%; P=0.02), and rupture of Bruch's membrane (20, 27, 39, and 36%; P=0.001). On the basis of multivariate analysis, the rate of metastasis increased with increasing age (P<0.001), ciliary body location (P<0.001), increasing tumor base (P<0.001), increasing tumor thickness (P<0.001), pigmented tumor (P=0.001), subretinal fluid (P=0.001), intraocular hemorrhage (P=0.045), and extraocular extension (P=0.036). Kaplan-Meier estimates of metastasis at 3, 5, and 10 were 8, 15, and 25% in Caucasians; 13, 13, and 13% in Hispanics; 4, 4, and 36% in Asians; and 8, 8, and 8% in African Americans. Compared with Caucasians, despite relative risk for metastasis of 0.31 for African Americans, 0.73 for Hispanics, and 1.42 for Asians, there was no statistical difference in metastasis, or death from uveal melanoma based on race. In summary, uveal melanoma showed similar prognosis for all races.

Cancer whole-genome sequencing: present and future.

Recent explosive advances in next-generation sequencing technology and computational approaches to massive data enable us to analyze a number of cancer genome profiles by whole-genome sequencing (WGS). To explore cancer genomic alterations and their diversity comprehensively, global and local cancer genome-sequencing projects, including ICGC and TCGA, have been analyzing many types of cancer genomes mainly by exome sequencing. However, there is limited information on somatic mutations in non-coding regions including untranslated regions, introns, regulatory elements and non-coding RNAs, and rearrangements, sometimes producing fusion genes, and pathogen detection in cancer genomes remain widely unexplored. WGS approaches can detect these unexplored mutations, as well as coding mutations and somatic copy number alterations, and help us to better understand the whole landscape of cancer genomes and elucidate functions of these unexplored genomic regions. Analysis of cancer genomes using the present WGS platforms is still primitive and there are substantial improvements to be made in sequencing technologies, informatics and computer resources. Taking account of the extreme diversity of cancer genomes and phenotype, it is also required to analyze much more WGS data and integrate these with multi-omics data, functional data and clinical-pathological data in a large number of sample sets to interpret them more fully and efficiently.

Relationship between malocclusion and heart rate variability indices in young adults: a pilot study.

OBJECTIVES: Heart rate variability (HRV) has been used to assess sympathetic and parasympathetic modulation of heart rate. Chronic stress relates to reduced HRV. Malocclusion has effects on quality of life, which can lead to chronic stress. Therefore, we hypothesized that malocclusion, as chronic stress, may contribute to reduced HRV. The aim of this study was to investigate the relationship between malocclusion and HRV indices in healthy young adults. METHODS: Thirty-seven non-smoking healthy subjects, aged 22 to 25 years, were examined. Malocclusion was defined by Angle classification. HRV indices included root mean square of successive differences, low frequency (LF), high frequency (HF) and ratio of LF to HF. The effects of malocclusion on quality of life and mental health were assessed using self-reported questionnaires, the condition-specific Oral Impacts on Daily Performances index (CS-OIDP) and the Hopkins Symptoms Checklist (HSCL), respectively. RESULTS: Significantly lower score of HF and higher heart rate (HR) level and CS-OIDP score were observed in subjects with malocclusion (n = 17) compared to those in the control subjects (n = 20) ( P <0.05). There was a positive correlation between HR and score of "anxiety" in HSCL ( P <0.05). CONCLUSIONS: The data showed an association between malocclusion and lower HRV. Based on our results, orthodontic treatment might contribute not only to improvement of oral esthetic and functional problems but also to improvement of stress and HRV indices.

Relationship between periodontal condition and arterial properties in an adult population in Japan.

UNLABELLED: Oral Diseases (2010) 16, 781-787 OBJECTIVE: This study addressed the relationship between periodontal condition and second derivative of the finger photoplethysmogram (SDPTG) in Japanese adults. SUBJECT AND METHODS: The Community Periodontal Index (CPI) and SDPTG were recorded in 415 subjects (mean age: 44.0 years). For assessing SDPTG, we mainly focused on the ratio of the absolute value of the height of the early negative 'b' wave and ratio of the late re-decreasing 'd' wave to the height of the initial positive 'a' wave, namely the b/a and d/a ratios. RESULTS: The CPI score was positively correlated with the b/a ratio (P < 0.001), and negatively correlated with the d/a ratio (P < 0.001). Logistic regression analysis showed that subjects with CPI scores ≥ 3 were more likely to have a higher level (male > -0.69, female > -0.64) of b/a ratio (Odds ratio = 1.7, P = 0.026) and lower level (male ≤ -0.29, female ≤ -0.32) of d/a ratio (Odds ratio = 2.2, P =0.001) than those with CPI scores 0-2, after adjusting for age, gender, smoking status, pulse rate and presence of hypertension. CONCLUSION: There was a statistical association between the CPI scores and SDPTG indices in Japanese adults.

Bilateral primary choroidal melanoma treated with bilateral plaque radiotherapy: a report of three cases.

PURPOSE: To report three cases of bilateral primary choroidal melanoma treated with bilateral plaque radiotherapy. METHODS: Retrospective, single-center case series. RESULTS: Case 1: In 1981, a 50-year-old man was diagnosed with a 5-mm-thick choroidal melanoma in the right eye (OD) and treated with plaque radiotherapy. In 1994, a 6.8-mm-thick choroidal melanoma in the left eye (OS) was treated with plaque radiotherapy. Final visual acuity was light perception OD and 20/20 OS at 24 years follow-up. Case 2: In 1983, a 53-year-old woman was diagnosed with a 3.5-mm-thick choroidal melanoma OS and treated with plaque radiotherapy. In 2001, an enlarging 2.5-mm-thick choroidal melanoma OD was treated with plaque radiotherapy. Final visual acuity was 20/30 OD and 20/20 OS at 22 years follow-up. Case 3: In 2001, a 92-year-old man was diagnosed with a 7.9-mm-thick choroidal melanoma OD treated with plaque radiotherapy. In 2003, an enlarging 2.8-mm-thick juxtapapillary choroidal melanoma was treated with plaque radiotherapy. Final visual acuity was 20/70 OD and 20/60 OS at 2.5 years follow-up. No patient showed ocular melanocytosis. Stable tumor regression was achieved in all six eyes. Metastatic disease did not develop in any case over 16 years of follow-up. CONCLUSIONS: Monitoring of both eyes of patients with uveal melanoma is important for the remote possibility of melanoma in the second eye. In these three patients, plaque radiotherapy allowed for preservation of the globes and some vision.

Cell transplantation after the coculture of skeletal myoblasts and mesenchymal stem cells in the regeneration of the myocardium scar: an experimental study in rats.

UNLABELLED: In myocardial infarction and Chagas's disease, some physiopathological aspects are common: cardiomyocyte loss due to ischemia leads to a reduction of contractility and heart function. Different cells have been proposed for cellular cardiomioplasty. OBJECTIVE: Our goal was to evaluate the method of co-culture of skeletal muscle (SM) and mesenchymal stem cells (MSC) for cell therapy of heart failure in Chagas's disease (CD) and myocardium postinfarction (MI). METHODS: For MI, 39 rats completed the study at 1 month. Seventeen rats received cell therapy into the scar and 22 rats only medium. For CD, 15 rats completed the study at 1 month including 7 that received cell therapy and eight followed the natural evolution. All animals underwent ecocardiographic analysis at baseline and 1 month. Left ventricular, ejection fraction, end systolic, and end dyastolic volume were registered and analyzed by ANOVA. The co-culture method of SM and MSC was performed at 14 days (DMEM, with 15% FCS, 1% antibiotic, IGF-I, dexamethasone). Standard stain analysis was performed. RESULTS: For MI ejection fraction in the animals that received the co-cultured cells increased from 23.52+/-8.67 to 31.45+/-8.87 (P=.006) versus the results in the control group: 26.68+/-6.92 to 22.32+/-6.94 (P=.004). For CD, ejection fraction in animals that received the co-cultured cells increased from 31.10+/-5.78 to 53.37+/-5.84 (P<.001) versus the control group values of 36.21+/-3.70 to 38.19+/-7.03 (P=0.426). Histopathological analysis of the animals receiving co-cultured cells demonstrated the presence of myogenesis and angiogenesis. CONCLUSION: The results validated the product of SM and MSC co-cultures for treatment of diseases.

Minor segmental wall motion abnormalities detected in patients with Chagas' disease have adverse prognostic implications

Recent data from our laboratory have shown that patients with the indeterminate form of Chagas' disease can have impairment of left ventricular contractility, as evaluated by the slope of the left ventricle end-systolic pressure-dimension relationship. We also showed that Chagas' disease patients with minimal baseline wall motion abnormalities detected by two-dimensional echocardiography have more intense contractility impairment when compared to patients with the indeterminate form of the disease without this abnormality. The prognostic implications of these findings have not been established. We evaluated 59 patients (37-76 years, mean = 55 years) with different clinical forms of Chagas' disease, who had normal left ventricular global systolic function at baseline (57.6 ± 6.9 percent) and who had at least one additional echo during clinical follow-up (0.4-17.6; mean 4.6 years). Group 1 consisted of 14 patients with minor baseline left ventricle wall motion abnormalities and group 2 consisted of 45 patients without these abnormalities. During follow-up, global left ventricle systolic function deterioration was observed in 10 group 1 patients (71.4 percent) and in only 10 group 2 patients (22.2 percent; P < 0.005). Age and duration of follow-up were not independent determinants of left ventricular function deterioration in these patients. The present data indicate that mild segmental left ventricular wall motion abnormalities are associated with worsening of systolic function in Chagas' disease patients who have normal baseline global systolic performance.

Proteomic profiling distinguishes astrocytomas and identifies differential tumor markers.

Methods to permit more precise delineation of astrocytomas of different grades may have therapeutic utility. The authors selectively microdissected pure populations of cells from normal brain and astrocytomas. They performed two-dimensional protein gel electrophoresis (2DGE) followed by protein sequencing. Differential expression was confirmed immunohistochemically. 2DGE identified proteomic patterns and proteins that differentiated normal brain from tumor and distinguished astrocytomas of increasing grade.

Cell transplantation: differential effects of myoblasts and mesenchymal stem cells.

BACKGROUND: Cellular transplantation has emerged as a novel therapeutic option for treatment of ventricular dysfunction. Both skeletal myoblasts (SM) and mesenchymal stem cells (MSC) have been proposed as ideal cell for this aim. The aim of this study is to compare the efficacy of these cells in improving ventricular function and to evaluate the different histological findings in a rat model of severe post-infarct ventricular dysfunction. METHODS: Myocardial infarction was induced in Wistar rats by left coronary occlusion. Animals with resulting ejection fraction (EF) lower than 40% were included. Heterologous SM were obtained by lower limb muscle biopsy and MSC by bone marrow aspiration. Nine days after infarction, rats received intramyocardial injection of SM (n=8), MSC (n=8) or culture medium, as control (n=11). Echocardiographic evaluation was performed at baseline and after 1 month. Histological evaluation was performed after HE and Gomori's trichrome staining and immunostainig against desmin, fast myosin and factor VIII. RESULTS: There was no difference in baseline EF and left ventricular end diastolic (LVEDV) and systolic volume (LVESV) between all groups. After 1 month a decrease was observed in the EF in the control group (27.0+/-7.10% to 21.46+/-5.96%, p=0.005) while the EF markedly improved in SM group (22.66+/-7.29% to 29.40+/-7.01%, p=0.04) and remained unchanged in the MSC group (23.88+/-8.44% to 23.63+/-10.28%, p=0.94). Histopathology identified new muscular fibers in the group that received SM and new vessels and endothelial cells in the MSC. CONCLUSION: Skeletal myoblasts transplantation resulted in myogenesis and improvement of ventricular function. In contrast, treatment with mesenchymal stem cells resulted in neoangiogenesis and no functional effect.

Molecular genetic and proteomic analysis of synchronous malignant gliomas.

Described is a patient with concurrent discrete gliomas: a pleomorphic xanthoastrocytoma with anaplastic features and an anaplastic oligoastrocytoma. The distinct and morphologically dissimilar tumors demonstrated similar genetic abnormalities by loss of heterozygosity and comparative genome hybridization. Clonality and proteomic analyses highlighted an independent origin for the two tumors. Proteomic methods may prove useful in cases where the differential diagnosis and pathogenetic origin of tumors are uncertain, as well as more globally for its ability to provide insight into specific expression of proteins that may serve as unique markers of tumorigenesis or as novel targets of therapy.

Estudo de doppler fluxometria em retalho de abdominoplastia / Study of Eco-Doppler fluxometry in abdominoplasty flap

A abdominoplastia tem-se difundido mundialmente, tanto esteticamente como de forma reparadora, e novas técnicas estão surgindo com o objetivo de minimizar as complicações isquêmicas do retalho e melhorar o contorno corporal. No período de janeiro a julho de 2002, vinte e uma pacientes, do sexo feminino, com idade variando entre 39 e 54 anos, apresentando alteração no abdome do tipo III e IV de BOZOLA, foram submetidas a abdominoplastia associada à lipoaspiração do abdome e flancos e descolamento apenas da porção central para plicatura da diástase muscular de acordo com a técnica de Saldanha(2001). Foi realizado um estudo com doppler fluxometria colo- rida dos vasos epigástricos superiores, inferiores e suas perfurantes músculo cutâneas, no pré-operatório e no décimo quinto dia de pós-operatório, avaliando a vascularização da parede abdominal superior e inferior, contabilizando os ramos perfurantes, calibre e fluxo sangüíneo dos vasos. Este estudo comprovou, através de doppler fluxometria, a preservação dos vasos perfurantes na região periumbilical e hipocôndrio e o aumento do calibre dos vasos em 9 e do fluxo sangüíneo em 56. A manutenção da irrigação sangüínea do retalho foi demonstrada clinicamente, através da boa evolução da cicatriz e ausência de complicações, como necrose da borda do retalho e seroma.

Abdominoplasty surgery has spread universally, both as aesthetic and reconstructive procedures, and new techniques are appearing with the goal of minimizing ischemic complications of the flap and bettering body contour. From January 2002 to July 2002, twenty one female patients, range of 30 to 54 years, presenting abdominal alterations classified as type III and IV of Bozola, were submitted to abdominoplasty combined with abdominal and flank lipossuction and central portion undermining for muscular diastasis plication according to Saldanha’s technique. Eco-doppler fluxometry of the superior and inferior epigastric vessels and of their cutaneous muscular perfurans was done preoperatively and 15 days after the surgery, assessing the superior and inferior abdominal wall circulation, counting the number of perfurans vessels, the diameter and vessels flow. This study showed, through eco-doppler fluxometry, perfurans vessel preservation at the periumbelical and hypocondric areas and enhancement of vessels diameter (9) and vessels flow (56). Blood flow maintenance was demonstrated clinically through the good scar evolution and absence of complications, as flap necrosis and seroma.

[Off-pump coronary artery bypass grafting/beating coronary artery bypass grafting for a patient with low left ventricular ejection fraction].

Beating coronary artery bypass grafting could be performed for a 47-year-old man with left ventricular ejection fraction (LVEF) of 9.3%. Post-operative LVEF was improved to 51.6%. Conventional coronary artery bypass grafting (CABG) used to be contraindicative for patients with LVEF below 20%. Recently, such patients are involved to indication of off-pump CABG (OPCAB) or beating CABG, because we consider OPCAB are lower complications than conventional CABG. We were able to bypass the circumflex for the patient while we had been used percutaneous cardio-pulmonary support (PCPS). We could perform beating coronary artery bypass grafting for a patient of the low LVEF.

Intracerebroventricular administration of ghrelin rapidly suppresses pulsatile luteinizing hormone secretion in ovariectomized rats.

Ghrelin, an endogenous growth hormone (GH) secretagogue, is shown to increase food intake, which action is similar to that of orexin, also a hypothalamic peptide. Since orexin suppresses pulsatile LH secretion in ovariectomized (OVX) rats, the present study was undertaken to investigate whether ghrelin also suppresses LH secretion. Effects of intracerebroventricularly injected ghrelin (0.1 nmol/0.3 microl) were examined in OVX rats treated with a small dose of 17beta-estradiol (E(2)). After ghrelin injection, pulsatile LH secretions which were ongoing in these E(2)-treated OVX rats were significantly suppressed for about 1 h, whereas GH secretion increased, peaking at 30 min. The main parameter suppressed by ghrelin was the pulse frequency, not the pulse amplitude, suggesting the hypothalamus as the site of ghrelin action. This study provides evidence that ghrelin acts not only in the control of food intake but also in the control of LH secretion.

Immunoglobulin heavy chain gene analysis of ocular adnexal extranodal marginal zone B-cell lymphoma.

PURPOSE: To clarify the cellular origin of extranodal marginal-zone B-cell lymphoma (EZML) of the mucosa-associated lymphoid tissue (MALT) type in ocular adnexa, the somatic mutation was analyzed in the immunoglobulin heavy-chain variable region (VH) gene. METHODS: Eight cases of EZML in the orbit and four in the conjunctiva were studied. The VH genes were amplified by a seminested PCR and sequenced directly. These were compared with the closest published VH germline segments to determine the somatic mutation frequency. Intraclonal microheterogeneity, which was termed the ongoing mutation frequency in the current study, was estimated by counting the number of single nucleotide substitutions in individual clones and dividing by the total number of nucleotides analyzed. Nine cases of gastrointestinal EMZL were also examined for comparison. RESULTS: The somatic mutation frequency varied between 2.0% and 12.7%, with a mean value of 7.9%. Ten cases with intraclonal microheterogeneity showed between one and six further substitutions. The average of ongoing mutation frequency was 0.11%, with a range of 0% to 0.25%. In the gastrointestinal EMZLs, the average of somatic mutation frequency was 8.5% (1.5%-14.2%) and of ongoing mutation frequency was 0.51% (0.25%-0.75%). CONCLUSIONS: The average of ongoing mutation frequency in ocular adnexal EMZL was lower than that in gastrointestinal EMZL. Both ocular adnexal and gastrointestinal EMZLs are derived from postgerminal center memory B cells, but the low ongoing mutation frequencies of ocular adnexal EMZL may result from less antigen stimulation and follicular colonization in the orbit relative to gastrointestinal EMZL.

Simultaneous intraluminal thermobrachytherapy: an in vitro study.

A multi-institutional study on simultaneous intraluminal thermobrachytherapy (SITB) for advanced esophageal cancer was conducted in Japan. In this study, brachytherapy was administered by a small radioactive source stepping through a catheter in the esophagus, and hyperthermia was also applied by an endoesophageal coil. However, experimental or clinical findings on the spatial distribution of its antitumor effects around the esophagus are not available. Therefore, we developed an in vitro model of SITB using a high-dose-rate iridium-192 stepping source and two human cancer cell lines (WiDr and A549), and determined the spatial distribution of the antitumor effects. According to this model, the antitumor effects steeply decreased as the source-cell distance increased when cells of both cell lines were irradiated with 5 Gy without heat. When WiDr cells, a more resistant cell line to radiation and heat, were simultaneously irradiated and heated for 30 min at 44 degrees C, the effects decreased much less steeply as the distance increased. For A549 cells, a more sensitive cell line, irradiation with hyperthermia even at 42 degrees C made the decrease in the effects smaller. The largest antitumor effects can be expected at 5 - 10 mm beneath the esophageal mucosa, where the endoesophageal coil can heat tissues most effectively. SITB can induce larger antitumor effects than brachytherapy alone, especially in submucosal disease, which would favor treatment of advanced cancer.

[Orbital development after enucleation without orbital implant in early childhood].

PURPOSE: To evaluate the development of orbital volume in five adults who underwent enucleation without orbital implant during early childhood, using reconstructed computed tomography(CT) images. MATERIALS AND METHODS: The orbital volume of 5 adults who underwent enucleation without orbital implants during early childhood was measured using CT images, and the results were compared between the anophthalmic orbit and the unaffected orbit in each case. The shape of maldevelopmental orbit and the relationship between orbital development and replacement of the prosthesis were also investigated. RESULTS: Orbital development in patients who underwent enucleation without orbital implant during early childhood was delayed in comparison with the unaffected orbit, and the delayed development was especially remarkable at the part of orbit corresponding to the equator of the eyeball. Maldevelopment of the orbit was severer in cases without replacement of the prosthesis than with it. CONCLUSION: For the development of orbital volume in anophthalmos after enucleation, orbital volume in place of the eyeball is required. Therefore, orbital implantation at the time of enucleation and replacement of the prosthesis with larger ones as the body grows are important.

The prohormone convertase enzyme 2 (PC2) is essential for processing pro-islet amyloid polypeptide at the NH2-terminal cleavage site.

Impaired processing of pro-islet amyloid polypeptide (proIAPP), the precursor of the beta-cell peptide islet amyloid polypeptide (IAPP) (amylin), has been implicated in islet amyloid formation in type 2 diabetes. The prohormone convertase enzymes PC3 (also known as PC1) and PC2 are localized to beta-cell secretory granules with proIAPP and proinsulin and are responsible for proinsulin processing. To determine whether PC2 might be essential for proIAPP processing, we performed Western blot analysis of freshly isolated islets from normal mice and mice lacking active PC2. As expected, the primary species of IAPP immunoreactivity in islets from wild-type mice was fully processed (4-kDa) IAPP, with only small amounts of the 8-kDa precursor (unprocessed proIAPP) present. Islets from heterozygous PC2 null mice were identical to wild-type animals, suggesting that half the normal complement of PC2 is sufficient for normal proIAPP processing. By contrast, in islets from homozygous PC2 null mice, the predominant IAPP-immunoreactive form was of intermediate size (approximately 6 kDa), with no detectable mature IAPP and slightly elevated amounts of the 8-kDa precursor form present. Thus, in the absence of PC2, proIAPP processing appears to be blocked at the level of a proIAPP conversion intermediate. Immunofluorescence of pancreas sections and immunoblotting using antisera raised to the NH2- and COOH-terminal flanking regions of mouse proIAPP demonstrated that the 6-kDa intermediate form was an NH2-terminally extended proIAPP conversion intermediate (processed only at the COOH-terminus). These data indicate that PC2 is essential for processing of proIAPP at the NH2-terminal cleavage site in vivo and that PC3 is likely only capable of processing proIAPP at the COOH-terminal cleavage site.