Everyday and everynight psychiatry - experiencing a ward cover shift through zoom

Introduction

The delivery of medical education has changed alongside the effects of COVID-19. As a result, the undergraduate psychiatry training for medical students at Guy’s King’s and St Thomas’ School of Medicine had to adapt rapidly. This poster portrays the journey in which the teaching sessions were developed and delivered throughout the first academic term of 2020-2021.

Objectives

To deliver an interactive online teaching day that can provide students with the knowledge and understanding of common psychiatric disorders in the interface of other medical conditions.

Methods

A clinical skills teaching day was developed to deliver the sessions via the online video calling platform Zoom. Published articles regarding online medical education as well as guidelines from the Royal College of Psychiatry were used as a resource to develop the structure. Feedback of the teaching day was collected via an anonymous survey.

Results

78 responses were collected in total from 4 teaching days. Overall satisfaction was high with a score of 86.5/100 in overall satisfaction. Themes for positive feedback included utilising actors in simulation (38% 30/78) and high interactivity within the teaching (31% 24/78). There were a number of students who found the whole day session online tiring (13% 10/78) and others felt the variation of scenarios were too limited (12% 9/78).

Conclusions

As lockdown has forced students to have less patient contact, they have suffered from the lack of learning opportunities. This teaching day showed the importance of organising high fidelity scenarios in order to try and fill the void that has been created due to COVID-19.

Combination gemcitabine plus S-1 versus gemcitabine plus cisplatin for advanced/recurrent biliary tract cancer: the FUGA-BT (JCOG1113) randomized phase III clinical trial

BACKGROUND

Gemcitabine plus cisplatin (GC) is the standard treatment of advanced biliary tract cancer (BTC); however, it causes nausea, vomiting, and anorexia, and requires hydration. Gemcitabine plus S-1 (GS) reportedly has equal to, or better, efficacy and an acceptable toxicity profile. We aimed to confirm the non-inferiority of GS to GC for patients with advanced/recurrent BTC in terms of overall survival (OS).

PATIENTS AND METHODS

We undertook a phase III randomized trial in 33 institutions in Japan. Eligibility criteria included chemotherapy-naïve patients with recurrent or unresectable BTC, an Eastern Cooperative Oncology Group Performance Status of 0 - 1, and adequate organ function. The calculated sample size was 350 with a one-sided α of 5%, a power of 80%, and non-inferiority margin hazard ratio (HR) of 1.155. The primary end point was OS, while the secondary end points included progression-free survival (PFS), response rate (RR), adverse events (AEs), and clinically significant AEs defined as grade ≥2 fatigue, anorexia, nausea, vomiting, oral mucositis, or diarrhea.

RESULTS

Between May 2013 and March 2016, 354 patients were enrolled. GS was found to be non-inferior to GC [median OS: 13.4 months with GC and 15.1 months with GS, HR, 0.945; 90% confidence interval (CI), 0.78-1.15; P = 0.046 for non-inferiority]. The median PFS was 5.8 months with GC and 6.8 months with GS (HR 0.86; 95% CI 0.70-1.07). The RR was 32.4% with GC and 29.8% with GS. Both treatments were generally well-tolerated. Clinically significant AEs were observed in 35.1% of patients in the GC arm and 29.9% in the GS arm.

CONCLUSIONS

GS, which does not require hydration, should be considered a new, convenient standard of care option for patients with advanced/recurrent BTC.

CLINICAL TRIAL NUMBER

This trial has been registered with the UMIN Clinical Trials Registry (http://www.umin.ac.jp/ctr/index.htm), number UMIN000010667.

Prognostic role of the length of tumour-vein contact at the portal-superior mesenteric vein in patients having surgery for pancreatic cancer

BACKGROUND

The length of tumour-vein contact between the portal-superior mesenteric vein (PV/SMV) and pancreatic head cancer, and its relationship to prognosis in patients undergoing pancreatic surgery, remains controversial.

METHODS

Patients diagnosed with pancreatic head cancer who were eligible for pancreatoduodenectomy between October 2002 and December 2016 were analysed. The PV/SMV contact was assessed retrospectively on CT. Using the minimum P value approach based on overall survival after surgery, the optimal cut-off value for tumour-vein contact length was identified.

RESULTS

Among 491 patients included, 462 underwent pancreatoduodenectomy for pancreatic head cancer. PV/SMV contact with the tumour was detected on preoperative CT in 248 patients (53·7 per cent). Overall survival of patients with PV/SMV contact exceeding 20 mm was significantly worse than that of patients with a contact length of 20 mm or less (median survival time (MST) 23·3 versus 39·3 months; P = 0·012). Multivariable analysis identified PV/SMV contact longer than 20 mm as an independent predictor of poor survival, whereas PV/SMV contact greater than 180° was not a predictive factor. Among patients with a PV/SMV contact length exceeding 20 mm on pretreatment CT, those receiving neoadjuvant therapy had significantly better overall survival than patients who had upfront surgery (MST not reached versus 21·6 months; P = 0·002).

CONCLUSION

The length of PV/SMV contact predicts survival, and may be used to suggest a role for neoadjuvant therapy to improve prognosis.

Randomized clinical trial of adjuvant gemcitabine chemotherapy versus observation in resected bile duct cancer

BACKGROUND

Although some retrospective studies have suggested the value of adjuvant therapy, no recommended standard exists in bile duct cancer. The aim of this study was to test the hypothesis that adjuvant gemcitabine chemotherapy would improve survival probability in resected bile duct cancer.

METHODS

This was a randomized phase III trial. Patients with resected bile duct cancer were assigned randomly to gemcitabine and observation groups, which were balanced with respect to lymph node status, residual tumour status and tumour location. Gemcitabine was given intravenously at a dose of 1000 mg/m² , administered on days 1, 8 and 15 every 4 weeks for six cycles. The primary endpoint was overall survival, and secondary endpoints were relapse-free survival, subgroup analysis and toxicity.

RESULTS

Some 225 patients were included (117 gemcitabine, 108 observation). Baseline characteristics were well balanced between the gemcitabine and observation groups. There were no significant differences in overall survival (median 62·3 versus 63·8 months respectively; hazard ratio 1·01, 95 per cent c.i. 0·70 to 1·45; P = 0·964) and relapse-free survival (median 36·0 versus 39·9 months; hazard ratio 0·93, 0·66 to 1·32; P = 0·693). There were no survival differences between the two groups in subsets stratified by lymph node status and margin status. Although haematological toxicity occurred frequently in the gemcitabine group, most toxicities were transient, and grade 3/4 non-haematological toxicity was rare.

CONCLUSION

The survival probability in patients with resected bile duct cancer was not significantly different between the gemcitabine adjuvant chemotherapy group and the observation group. Registration number: UMIN 000000820 (http://www.umin.ac.jp/).

A randomized phase II study of S-1 plus oral leucovorin versus S-1 monotherapy in patients with gemcitabine-refractory advanced pancreatic cancer

This is the first phase II trial in which adding oral leucovorin (LV) to S-1 (SL) significantly prolonged progression-free survival (PFS) when compared with S-1 monotherapy (S) in patients with gemcitabine-refractory advanced pancreatic cancer (PC). The significantly better PFS and disease control rate with SL than with S suggest that the antitumor activity of S-1 is enhanced by LV in advanced PC.

Background

We evaluated the efficacy and toxicity of adding oral leucovorin (LV) to S-1 when compared with S-1 monotherapy in patients with gemcitabine-refractory pancreatic cancer (PC).

Patients and methods

Gemcitabine-refractory PC patients were randomly assigned in a 1:1 ratio to receive S-1 at 40, 50, or 60 mg according to body surface area plus LV 25 mg, both given orally twice daily for 1 week, repeated every 2 weeks (SL group), or S-1 monotherapy at the same dose as the SL group for 4 weeks, repeated every 6 weeks (S-1 group). The primary end point was progression-free survival (PFS).

Results

Among 142 patients enrolled, 140 were eligible for efficacy assessment (SL: n = 69 and S-1: n = 71). PFS was significantly longer in the SL group than in the S-1 group [median PFS, 3.8 versus 2.7 months; hazard ratio (HR), 0.56; 95% confidence interval (CI), 0.37–0.85; P = 0.003]). The disease control rate was significantly higher in the SL group than in the S-1 group (91% versus 72%; P = 0.004). Overall survival (OS) was similar in both groups (median OS, 6.3 versus 6.1 months; HR, 0.82; 95% CI, 0.54–1.22; P = 0.463). After adjusting for patient background factors in a multivariate analysis, OS tended to be better in the SL group (HR, 0.71; 95% CI, 0.47–1.07; P = 0.099). Both treatments were well tolerated, although gastrointestinal toxicities were slightly more severe in the SL group.

Conclusion

The addition of LV to S-1 significantly improved PFS in patients with gemcitabine-refractory advanced PC, and a phase III trial has been initiated in a similar setting.

Clinical trials number

Japan Pharmaceutical Information Center: JapicCTI-111554.

Phase I study of TAS-102 treatment in Japanese patients with advanced solid tumours

BACKGROUND

TAS-102 consists of α, α, α-trifluorothymidine (TFT) and an inhibitor of thymidine phosphorylase (TPI). We conducted a dose-escalation phase I study in Japanese patients with advanced solid tumours.

METHODS

TAS-102 was administered twice daily on days 1-5 and days 8-12 in a 28-day cycle to patients with solid tumours refractory to standard chemotherapy, to determine its maximum tolerated dose (MTD), dose-limiting toxicities (DLTs), and pharmacokinetics (PKs). MTD was evaluated in cycle 1.

RESULTS

Safety and PKs were evaluated in 21 patients treated with TAS-102 at 30, 40, 50, 60, or 70 mg m(-2) per day. DLTs, such as grade 4 leucopenia, grade 4 neutropenia, and grade 4 thrombocytopenia, were observed in two patients at doses of 30 and 70 mg m(-2). α, α, α-trifluorothymidine and TPI exposures increased dose dependently, and the percentage of decrease in neutrophil count and TFT exposure were significantly correlated. The disease control rate was 50.0% with a median progression-free survival of 2.4 months in 18 colorectal cancer patients. The dose of TAS-102 was not increased above 70 mg m(-2) per day because of the increased tendency for grade 3 and 4 neutropenia, and 70 mg m(-2) per day was the recommended dose for phase II studies.

CONCLUSIONS

TAS-102 at 70 mg m(-2) per day was tolerated in Japanese patients with advanced solid tumours. Phase II studies are ongoing in patients with colorectal cancer.

Phase I study of nimotuzumab, a humanized anti-epidermal growth factor receptor (EGFR) IgG1 monoclonal antibody in patients with solid tumors in Japan

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Background: Nimotuzumab, a humanized IgG1 monoclonal antibody targeting EGFR, has been used in head & neck cancer or malignant glioma outside Japan, and MTD including severe skin rash were not observed up to 800mg/body. This phase I study of nimotuzumab was conducted to investigate the safety profile, MTD, DLT, PK, human antibody against nimotuzumab (HAHA) in Japanese patients (pts), and PD analysis (activation of EGFR, Akt, MAPK, Ki67) was done. Methods: Pts with advanced solid tumors having no available standard therapy were enrolled. Nimotuzumab was given intravenously at dose levels of nimotumumab 100, 200 and 400mg/body, weekly. Blood, skin samples before treatment and after 4th infusion and pre-treatment tumor were collected for PD analysis. Results: 4 pts were enrolled in each level (total 12 pts). Pt characteristics were M/F 5/7, median age 57 years, ECOG PS 0/1 7/5. No grade 3 or 4 toxicities and no DLT were observed, and MTD was not determined. The major adverse event was grade 1 or 2 skin rash (58%, 7/12). Neither infusion reaction nor HAHA was observed. AUC0-inf, Cmax and t1/2 increased and CL deceased by dose dependent manner, indicating nonlinear PK characteristic. SD and PD were observed in 8 patients (67%) and4 patients (33%), without objective responses. Median time to progression was 4 months. Time to progression seemed to be longer in the pts with amplified gene copy number of EGFR though the number of pts was limited. Conclusions: Weekly infusion of nimotuzumab was well tolerated up to 400 mg/body in Japanese pts. A correlation between anti-tumor activity and EGFR amplification was speculated. Additional PD analysis is currently ongoing.

No significant financial relationships to disclose.

Phase II study of gemcitabine chemotherapy alone for locally advanced pancreatic carcinoma: JCOG 0506

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Background: Fluorouracil (5-FU) chemoradiotherapy has been accepted as standard care for locally advanced pancreatic cancer (LAPC); however, it has not been shown to be superior to chemotherapy alone in gemcitabine (Gem) era. The present multicenter phase II study was conducted to evaluate the efficacy and the safety for the screening of Gem monotherapy against LAPC. Methods: Eligibility criteria included the following: patients (pts) with histologically or cytologically proven pancreatic adenocarcinoma or adenosquamous carcinoma, pts with UICC clinical stage III (T4N0–1 and M0), all lesions are assumed to be included in the radiation field of 15 cm square, age 20 or older, no prior treatment for LAPC, ECOG performance status of 0, 1 or 2, and adequate organ function. Gem was given intravenously at a dose of 1,000 mg/m2 over 30 minutes on days 1, 8 and 15, repeated every 4 weeks until disease progression. The primary endpoint was %1-year overall survival. A sample size of 50 was required with one-sided alpha of 0.20, beta of 0.10, expected %1-year survival of 40% and threshold %1-year survival of 25%. Results: Between Jan. 06 and Feb. 07, 50 pts from 14 institutions were registered. Patient characteristics were: median age; 67.5 (45–80), male/female; 35/15, PS 0/1/2; 30/20/0, pancreatic head/body-tail; 26/24. The major grade 3–4 adverse events were neutropenia (62%), leucopenia (32%), thrombocytopenia (18%), fatigue (12%), infection-biliary tree (10%), anorexia (8%), and nausea (6%). Hematological toxicity was mostly transient and there was no episode of infection with grade 3–4 neutropenia. There were no treatment-related deaths during the study. Serum CA 19–9 level was reduced by >50% in 37.5% of 40 pts with baseline CA19–9 >100U/ml. Up to the final follow-up in Apr. 08, the median overall survival was 1.25 years (95% CI, 1.06–1.71 years) with a %1-year survival of 64.8% (95% CI, 49.6–76.4%), and the null hypothesis (%1-y survival=25%) was rejected (p<0.0001). Conclusions: Gem monotherapy demonstrated far better survival than historical data of 5-FU chemoradiotherapy in LAPC pts with mild toxicities. In future randomized trial, we will select Gem chemotherapy as a referential arm to compare with the chemoradiotherapy regimen which is under phase II evaluation for LAPC.

No significant financial relationships to disclose.

Impact of hemoglobin level on survival in definitive chemoradiotherapy for T4/M1 lymph node esophageal cancer

We retrospectively investigated the impact of the pre-chemoradiotherapy hemoglobin level (pre-CRT Hb level) for T4 and/or M1 lymph node (LYM) squamous cell carcinoma of the esophagus. Chemotherapy consisted of protracted infusion with 5-fluorouracil (5-FU) at 400 mg/m(2)/day on days 1-5 and 8-12, combined with cisplatin at 40 mg/m(2)/day on days 1 and 8, repeated twice at a 5-week interval. Concurrent radiation therapy was started on day 1 and delivered at 2 Gy/day for five days a week for a total radiation dose of 60 Gy, with a two-week break after a cumulative dose of 30 Gy. Several factors considered to be related with treatment outcome were evaluated by univariate and multivariate analysis. A total of 48 patients with T4/M1 LYM (lymphocyte) esophageal cancer treated with chemoradiotherapy (CRT) between September 2002 and April 2005 were enrolled. The complete response rate to this regimen was 44% and median survival time was 13.6 months, with a median follow-up period of 26.8 months. Median pre-CRT Hb level was 13.5 (10.4-15.3) g/dL. The CR rate in patients with a pre-CRT Hb level of 13 g/dL or less was only 24% but it was 60% in those with a level that was more than 13 g/dL (P=0.01). As for survival, anovarevealed that a pre-CRT Hb of 13 g/dL or less was a significant prognostic factor with a hazard ratio of 0.45 (95% confidence interval [CI]); 0.21-0.97, P=0.04), while on manova, including performance status, tumor size, TNM stage and pre-CRT Hb level, a pre-CRT Hb level of 13 g/dL or less was the only significant prognostic factor, with a hazard ratio of 0.35 (95% CI; 0.13-0.90, P=0.03). In conclusion, the pre-CRT Hb level may be an important determinant of outcome in patients with T4/M1 LYM squamous cell carcinoma of the esophagus.

Application of the RTOG recursive partitioning analysis classification to brain metastases from colorectal cancer

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Background: Colorectal cancer infrequently causes brain metastases (BMs). Recently, the incidence of BMs from colorectal cancer (CRC) has been reported to be increasing as 3 % of all metastatic CRCs, especially in patients (pts) with lung metastases (LMs). The RTOG previously developed three prognostic classes for BMs using a recursive partitioning analysis (RPA) classification, including Karnofsky performance status, controlled primary tumor, extracranial metastases, and an age. However, the relevance of this classification for CRC remains unclear, because only a few CRC pts were included in the RTOG database. The present studies retrospectively evaluate the usefulness of RPA classification for BMs from CRC. Methods: The subjects were consecutive 290 metastatic CRCs without symptomatic BMs who treated with any chemotherapy initiated in our institution between 2002 and 2005. The treatment of BMs, including whole brain radiation therapy (WBRT), surgery, and stereotactic radiosurgery (SRS), were indicated for pts whose life expectancy was considered to exceed 3 months (M). Results: BMs were detected in 20 pts out of 133 (15%) with LMs at base line, with a median follow-up time of 17.7 M. In the remaining 157 pts, BMs were found in 3 pts out of 41(7%) who had developed LMs during follow-up and 2 pts out of 116 (2%) without LMs. In total, overall incidence of BMs was 9% (25/ 290). Median duration from the diagnosis of LMs to BMs was 12 M (range: 4.4–33.6). According to RPA, the 25 pts with BMs were classified into Class I 0 (0%), Class II 12 (48%) and Class III 13 (52%). Treatments for BMs were performed to all pts of Class II, and to 6 pts (46%) of Class III. Median overall survivals from detecting BMs were Class II 9.7 M and Class III 3.0 M (logrank test; p=0.02). In the 18 pts treated for BMs, median BMs progression-free survival of Class II and Class III were 3.0 M and 3.1 M. Conclusions: It is suggested that the incidence of BMs from CRC is more common than previously reported. Overall survivals for BMs reproduce the results from RPA classification.

No significant financial relationships to disclose.

[Noninvasive positive-pressure ventilation in an elderly woman with acute respiratory failure caused by influenza a virus pneumonia]

A 79-year-old woman was admitted on January 18, 2000, with a lumbar compression fracture. Two days after admission, a chest X-ray film showed reticular infiltrates in the right lung field. She was diagnosed as having pneumonia and was treated with antibiotics. Despite this therapy, her symptoms did not improve and the infiltrates diffusely extended to involve both lungs on chest X-ray films. She was placed on noninvasive positive pressure ventilation (NIPPV) for progressive respiratory failure at 5 days after admission in order to avoid endotracheal intubation. Her hypoxemia was immediately improved by oronasal bilevel positive airway pressure ventilation (BiPAP) and chest X-ray films revealed improvement of the reticular infiltrates. Measurement of viral antibody titers showed that the cause of acute respiratory failure was influenza A virus pneumonia. In conclusion, NIPPV may reduce the need for intubation of elderly patients with acute respiratory failure, as well as chronic obstructive pulmonary disease (COPD) patients.

Interaction of hepatitis B virus X protein with a serine protease, tryptase TL2 as an inhibitor

X protein of hepatitis B virus (HBV) transactivates transcription of various viral and cellular genes. It has been suggested that X protein plays a major role in hepatocarcinogenesis by HBV. The protein possesses amino acid sequence homology to the functionally essential domain of Kunitz-type serine protease inhibitors. This Kunitz domain-like sequence in X protein is indispensable for the transactivation function. To clarify whether X protein has a serine protease inhibitor activity, a search was made for serine proteases which interact with, but not degrade X protein. Tryptase TL2, one of serine proteases in hepatic cells, was found to directly interact with X protein without degradation. Moreover, the activities of tryptase TL2 and an analogous protease were substantially inhibited by X protein. These results suggest that transactivation function of X protein is exerted by modulation of the hepatic serine protease activity, giving rise to quantitative or qualitative change of cellular transcription factor(s) through protection from proteolytic degradation and/or suppression of processing.

Processing protease for gp160 human immunodeficiency virus type I envelope glycoprotein precursor in human T4+ lymphocytes. Purification and characterization

A processing protease for the human immunodeficiency virus type I (HIV-I) envelope glycoprotein gp160 precursor has been purified to homogeneity from the post-nuclear membrane fraction of a human T4+ lymphocyte clone. Most of the processing activity was found to be present in the fractions of endoplasmic reticulum and Golgi apparatus of the cells. The purified enzyme has a monomeric structure with a molecular mass of 26 +/- 3 kDa, as judged by gel-permeation liquid chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing and nonreducing conditions. The purified enzyme converted gp160 to gp120 and gp41, showing a pH optimum of 6.5-7.0. Direct amino acid sequencing of the amino terminus of the product gp41 revealed that the cleavage site of gp160 was between Arg511 and Ala512. The enzyme activity was inhibited by trypsin-type protease inhibitors, but was not affected by CaCl2, MgCl2 or chelating agents. The properties of the purified enzyme are clearly distinct from those of processing proteases reported previously. Although the significance of the enzyme in vivo is not currently certain, judging from its cleavage specificity and subcellular localization, this endopeptidase appears to be a processing enzyme for the human immunodeficiency virus type I gp160 precursor protein in human T cells.

Isolation and characterization of a novel trypsin-like protease found in rat bronchiolar epithelial Clara cells. A possible activator of the viral fusion glycoprotein

A novel trypsin-like protease associated with rat bronchiolar epithelial Clara cells, named Tryptase Clara, was purified to homogeneity from rat lung by a series of standard chromatographic procedures. The enzyme has apparent molecular masses of 180 +/- 16 kDa on gel filtration and 30 +/- 1.5 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing conditions. Its isoelectric point is pH 4.75. Studies with model peptide substrates showed that the enzyme preferentially recognizes a single arginine cleavage site, cleaving Boc-Gln-Ala-Arg-4-methylcoumaryl-7-amide most efficiently and having a pH optimum of 7.5 with this substrate. The enzyme is strongly inhibited by aprotinin, diisopropylfluorophosphate, antipain, leupeptin, and Kunitz-type soybean trypsin inhibitor, but inhibited only slightly by Bowman-Birk soybean trypsin inhibitor, benzamidine, and alpha 1-antitrypsin. Immunohistochemical studies indicated that the enzyme is located exclusively in the bronchiolar epithelial Clara cells and colocalized with surfactant. An immunoreactive protein with a molecular mass of 28.5 kDa was also detected in airway secretions by Western blotting analyses, suggesting that the 30-kDa protease in Clara cells is processed before or after its secretion. Proteolytic cleavage of the hemagglutinin of influenza virus is a prerequisite for the virus to become infectious. Tryptase Clara was shown to cleave the hemagglutinin and activate infectivity of influenza A virus in a dose-dependent way. These results suggest that the enzyme is a possible activator of inactive viral fusion glycoprotein in the respiratory tract and thus responsible for pneumopathogenicity of the virus.

Tryptase TL2 in the membrane of human T4+ lymphocytes is a novel binding protein of the V3 domain of HIV-1 envelope glycoprotein gp 120

A novel membrane-bound serine esterase in cultured human T4+ lymphocytes, recently purified and named tryptase TL2, binds specifically to the external envelope protein gp 120 of HIV-1, interacting with its V3 domain. This binding was selectively blocked by inhibitors of tryptase TL2 with a GPCR sequence in their reactive site, synthetic peptides corresponding with the sequences of the V3 domains of various HIV-1 strains with the GPGR sequence, and antibody against tryptase TL2, or neutralizing antibody against the V3 domain of HTLV-IIIB. These findings suggest that tryptase TL2 is a binding protein of the V3 domain of HIV-1 envelope glycoprotein.

A novel membrane-bound serine esterase in human T4+ lymphocytes immunologically reactive with antibody inhibiting syncytia induced by HIV-1. Purification and characterization

A novel membrane-bound serine esterase, named tryptase TL2, which is immunologically reactive with the antibody inhibiting induction of syncytia by human immunodeficiency virus-1 (HIV-1) (Hattori, T., Koito, A., Takatsuki, K., Kido, H., and Kutunuma, N. (1989) FEBS Lett., 248, 48-52), has been purified from a human T4+ lymphocyte clone. The enzyme has a molecular mass of 198 +/- 15 kDa, as judged by gel-permeation liquid chromatography, and is composed of two subunits of 32 kDa and four subunits of 28 kDa, as shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Studies with model peptide substrates showed that the enzyme preferentially recognized L-arginine and cleaved Boc-Gln-Gly-Arg-4-methyl-coumaryl-7-amide and Boc-Gln-Ala-Arg-4-methyl-coumaryl-7-amide with high efficiency at a pH optimum of 8.5. The enzyme was strongly inhibited by the envelope glycoprotein gp 120 of HIV-1, by synthetic peptides with the sequence GPGR in their center, which corresponds to the principal neutralizing epitope of the gp 120s of various HIV-1 strains, by Kunitz-type inhibitors with the sequence GPCR in their active site, such as trypstatin, HI30, and [Arg15, Glu52]aprotinin and by the microbial inhibitors leupeptin and antipain. Studies on the subcellular distribution of tryptase TL2, immunohistochemical analysis, and cell surface radioiodination indicated that the enzyme is mainly localized in the plasma membrane.

Protease-specificity of Kunitz inhibitor domain of Alzheimer's disease amyloid protein precursor

The putative inhibitor domain of Alzheimer's disease amyloid protein precursor was purified from E. coli containing a synthetic gene encoding the Kunitz domain. The purified protein (A4 inhibitor) inhibited the activity of trypsin, forming a 1:1 molar complex with the enzyme. It also strongly inhibited plasmin (Ki = 7.5 x 10(-11) M) from human serum and tryptase (Ki = 2.2 x 10(-10) M) from rat mast cells (tryptase M). In addition, it inhibited rat pancreatic trypsin, alpha-chymotrypsin and kallikrein and human serum kallikrein, but did not inhibit rat chymase, pancreatic elastase, alpha-thrombin, urokinase, papain or cathepsin B.