Interdisciplinary combined sacrocolporectopexy: Results after one-year follow-up

Objective

Multicompartmental pelvic floor descensus typically affects women after menopause, leading to a combination of faecal and urinary incontinence, dyspareunia, and evacuation disorders. The aim of this study was to access postoperative quality of life and complications as well as outcome after one-year follow-up after operation of multicompartmental pelvic floor prolapse (POP).

Methods

All Patients undergoing ventral mesh rectopexy by surgical department and anterior mesh sacrocolpopexy by gynecologists at the same time between 2015 and 2020 were enrolled. The study is a retrospective cohort study approved by the local Ethics committee. Follow-up was scheduled at 6 weeks, 6, and 12 months and consisted of clinical examination and questionnaires. Perioperative and long-time morbidity was assessed according to the Clavien-Dindo classification. Quality of life and patients’ satisfaction were evaluated at each consultation.

Results

Twenty-seven patients were included. All patients were seen at one-year follow-up.

Demographic and clinical features are reported in Table 1. Preoperatively, 22 patients (81.5%) were diagnosed with stage II-III (POP-Q) prolapse and severe multicompartment descensus detected on Magnetic Resonance (MR). Laparoscopic surgery was performed in 92.5% of cases and intraoperative conversion was necessary in 2 cases. In 15 cases (55%) a Dynamesh® Visible, in 11 cases (41%) a Gynamesh®, and in one (4%) case a Surgipro™ Mesh was used. No severe complications (Clavien-Dindo >=3) occurred postoperatively. 90-day mortality was 0%. Intraoperatively, a total of 1 vaginal, and 2 bladder lesions were corrected and healed without consequences. At 1 year, patients reported a high level of satisfaction and massive improvement of QoL (8.5 Pt. VAS Scale). During follow-up, one patient had to be reoperated because of incisional hernia and one to cover vaginal mesh exposure. A tension free vaginal tape (TVT) had to be inserted in 4 patients (15%) due to new onset of urinary incontinence. Symptomatic recurrence of prolapse did not occur.

Conclusion

Interdisciplinary combined sacrocolporectopexy is an effective therapy of multicompartmental pelvic floor descensus. It is a safe procedure with low perioperative morbidity and high patients’ satisfaction. Therefore, it might be the procedure of choice to correct multicompartmental POP.

Transmission of HIV Drug Resistance and the Predicted Effect on Current First-line Regimens in Europe

Transmitted human immunodeficiency virus drug resistance in Europe is stable at around 8%. The impact of baseline mutation patterns on susceptibility to antiretroviral drugs should be addressed using clinical guidelines. The impact on baseline susceptibility is largest for nonnucleoside reverse transcriptase inhibitors.

Background. Numerous studies have shown that baseline drug resistance patterns may influence the outcome of antiretroviral therapy. Therefore, guidelines recommend drug resistance testing to guide the choice of initial regimen. In addition to optimizing individual patient management, these baseline resistance data enable transmitted drug resistance (TDR) to be surveyed for public health purposes. The SPREAD program systematically collects data to gain insight into TDR occurring in Europe since 2001.

Methods. Demographic, clinical, and virological data from 4140 antiretroviral-naive human immunodeficiency virus (HIV)–infected individuals from 26 countries who were newly diagnosed between 2008 and 2010 were analyzed. Evidence of TDR was defined using the WHO list for surveillance of drug resistance mutations. Prevalence of TDR was assessed over time by comparing the results to SPREAD data from 2002 to 2007. Baseline susceptibility to antiretroviral drugs was predicted using the Stanford HIVdb program version 7.0.

Results. The overall prevalence of TDR did not change significantly over time and was 8.3% (95% confidence interval, 7.2%–9.5%) in 2008–2010. The most frequent indicators of TDR were nucleoside reverse transcriptase inhibitor (NRTI) mutations (4.5%), followed by nonnucleoside reverse transcriptase inhibitor (NNRTI) mutations (2.9%) and protease inhibitor mutations (2.0%). Baseline mutations were most predictive of reduced susceptibility to initial NNRTI-based regimens: 4.5% and 6.5% of patient isolates were predicted to have resistance to regimens containing efavirenz or rilpivirine, respectively, independent of current NRTI backbones.

Conclusions. Although TDR was highest for NRTIs, the impact of baseline drug resistance patterns on susceptibility was largest for NNRTIs. The prevalence of TDR assessed by epidemiological surveys does not clearly indicate to what degree susceptibility to different drug classes is affected.

HIV-HCV co-infected patients with low CD4+ cell nadirs are at risk for faster fibrosis progression and portal hypertension

Patients co-infected with the human immunodeficiency virus (HIV) and the hepatitis C virus (HCV) are fraught with a rapid fibrosis progression rate and with complications of portal hypertension (PHT) We aimed to assess the influence of immune function [Centers of Disease Control and Prevention (CDC) stage] on development of PHT and disease progression in HIV-HCV co-infection. Data of 74 interferon-naïve HIV-HCV co-infected patients undergoing liver biopsy, measurement of portal pressure and of liver stiffness and routine laboratory tests (including CD4+ cell count, HIV and HCV viral load) were analysed. Time of initial exposure (risk behaviour) was used to assess fibrosis progression. Fibrosis progression, time to cirrhosis and portal pressure were correlated with HIV status (CDC stage). HIV-HCV patients had rapid progression of fibrosis [0.201 +/- 0.088 METAVIR fibrosis units/year (FU/y)] and accelerated time to cirrhosis (24 +/- 13 years), high HCV viral loads (4.83 x 10(6) IU/mL) and a mean HVPG at the upper limit of normal (5 mmHg). With moderate or severe immunodeficiency, fibrosis progression was even higher (CDC-2 = 0.177 FU/y; CDC-3 = 0.248 FU/y) compared with patients with higher CD4+ nadirs (CDC-1 = 0.120 FU/y; P = 0.0001). An indirect correlation between CD4+ cell count and rate of fibrosis progression (R = -0.6654; P < 0.001) could be demonstrated. Hepatic venous pressure gradient (HVPG) showed early elevation of portal pressure with median values of 4, 8 and 12 mmHg after 10, 15 and 20 years of HCV infection for CDC-3 patients. Patients treated with highly active anti-retroviral therapy (HAART) had similar rates of progression and portal pressure values than patients without HAART. Progression of HCV disease is accelerated in HIV-HCV co-infection, being more pronounced in patients with low CD4+ cell count. A history of a CD4+ cell nadir <200/microL is a risk factor for rapid development of cirrhosis and PHT. Thus, HCV treatment should be considered early in patients with HIV-HCV co-infection and largely preserved CD4+ cell counts.

German-Austrian recommendations for HIV-therapy in pregnancy and in HIV-exposed newborn - update 2005

In Germany during the last years about 200-250 HIV infected pregnant women delivered a baby each year, a number that is currently increasing. To determine the HIV-status early in pregnancy voluntary HIV-testing of all pregnant women is recommended in Germany and Austria as part of prenatal care. In those cases, where HIV infection was known during pregnancy, since 1995 the rate of vertical transmission of HIV was reduced to 1-2%. - This low transmission rate has been achieved by the combination of anti-retroviral therapy of pregnant women, caesarean section scheduled before onset of labour, anti-retroviral post exposition prophylaxis in the newborn and refraining from breast-feeding by the HIV infected mother. To keep pace with new results in research, approval of new anti-retroviral drugs and changes in the general treatment recommendations for HIV infected adults, in 1998, 2001 and 2003 an interdisciplinary consensus meeting was held. Gynaecologists, infectious disease specialists, paediatricians, pharmacologists, virologists and members of the German AIDS Hilfe (NGO) were participating in this conference to update the prevention strategies. A third update became necessary in 2005. The updating process was started in January 2005 and was terminated in September 2005. The guidelines provide new recommendations on the indication and the starting point for therapy in pregnancies without complications, drugs and drug combinations to be used preferably in these pregnancies and updated information on adverse effects of anti-retroviral drugs. Also the procedures for different scenarios and risk constellations in pregnancy have been specified again. With these current guidelines in Germany and Austria the low rate of vertical HIV-transmission should be further maintained.

Specific immune recognition of pancreatic carcinoma by patient-derived CD4 and CD8 T cells and its improvement by interferon-gamma

Pancreatic carcinoma is a very aggressive disease and little is known about its immunobiology. We here describe the presence in pancreatic cancer patients of spontaneously induced functional CD4 and CD8 memory/effector T cells reactive to autologous tumor cells or to the pancreatic cancer associated antigen, MUC-1. Such specific cells were present in the bone marrow or peripheral blood of most of the 23 tested patients. Low dose stimulation of primary cultures of pancreatic cancer cells with 500 IU/ml IFN-gamma for 72 h enhanced HLA-I expression and induced the de novo expression of HLA-II molecules. This led to a much better immune recognition by autologous HLA-I restricted and purified CD8 T cells and allowed tumor cell recognition by HLA-II restricted purified CD4 T-helper cells. Thus, interferon-gamma appears to be a useful adjuvant cytokine to enhance the immunogenicity of a patients' tumor cells and their recognition by tumor reactive immune cells.

Randomized clinical trial of pylorus-preserving duodenopancreatectomy versus classical Whipple resection—long term results

Background

It is not known whether pylorus-preserving duodenopancreatectomy is as effective as the classical Whipple procedure in the resection of pancreatic and periampullary tumours. A prospective randomized trial was undertaken to compare the results of the two procedures.

Methods

Clinical data, histological findings, short-term results, survival and quality of life of all patients having surgery for suspected pancreatic or periampullary cancer between June 1996 and September 2001 were analysed.

Results

Two hundred and fourteen patients were randomized to undergo either a standard or a pylorus-preserving Whipple resection. After exclusion of 84 patients on the basis of intraoperative findings, 130 patients (66 standard Whipple operation and 64 pylorus-preserving resection) were entered into the trial. Of these, 110 patients with proven adenocarcinoma (57 standard Whipple and 53 pylorus-preserving resection) were analysed for long-term survival and quality of life. There was no difference in perioperative morbidity. Long-term survival, quality of life and weight gain were identical after a median follow-up of 63·1 (range 4–93) months. At 6 months, capacity to work was better after the pylorus-preserving procedure (77 versus 56 per cent; P = 0·019).

Conclusion

Both procedures were equally effective for the treatment of pancreatic and periampullary cancer. Pylorus-preserving Whipple resection offers some minor advantages in the early postoperative period, but not in the long term.

Transverser Koloplastik-Pouch nach tiefer anteriorer Resektion

INTRODUCTION

A colon J pouch (CJP) still represents the standard rectal reservoir after low anterior resection. Though the CJP shows favourable early functional results, pouch evacuation problems tend to occur in the long term. The transverse coloplasty pouch (TCP), developed by our group allows comparable early functional results while avoiding evacuation problems. We report our experience with the TCP at the University Hospital of Heidelberg, Germany, and examine the risk of anastomotic leaks with this technique.

METHODS

Between 1 October 2001 and 31 May 2003, 201 patients with rectal tumours underwent resection. Eighty-two patients with formation of TCP were enrolled in the study.

RESULTS

During the creation of the TCP, no technical problems occurred, and the overall morbidity was 28%, including anastomotic leaks in seven patients (8.5%) and bleeding in two. The reoperation rate was 8.5%. An association between postoperative morbidity and preoperative radiation therapy could not be established. The hospital mortality rate was 3.6%.

CONCLUSIONS

The use of TCP is a safe procedure which has gained worldwide acceptance in a short time, representing a technically straightforward procedure. Independently of patient size, habitus, and bulkiness of the colon, a TCP can always be performed after low rectal resection.

Quality of life of HIV-infected patients: psychometric properties and validation of the German version of the MQOL-HIV

OBJECTIVE

To determine the psychometric properties of the recently developed German version of the Multidimensional Quality of Life Questionnaire for HIV/AIDS (MQOL-HIV) and to test its performance in a sample of HIV-infected patients.

METHODS

Two-hundred and seven outpatients with HIV/AIDS were interviewed with the German version of the MQOL-HIV; 109 patients were interviewed a second time approximately 2 weeks later. Patients also completed the Beck Depression Inventory (BDI) and the World Health Organization Disability Assessment Schedule II (WHODAS II).

RESULTS

The German version of the MQOL-HIV showed satisfactory internal consistency (r: 0.74-0.85, sexual functioning: r = 0.61) and test-retest reliability in most subscales (r: 0.74-0.89, medical care: r = 0.67). Convergent validity with WHO-DAS II and BDI was satisfactory for most domains. Exploratory factor analysis yielded a seven-factor solution with separate factors for physical, emotional, cognitive, social and financial aspects, sexual functioning and medical care. CD4 count and source of infection were associated with most QOL domains, whereas age and gender showed no major impact on QOL. High rates of missing values were seen in the partnership domain and substantial ceiling effects in the area of medical care.

CONCLUSIONS

Overall the German version of the MQOL-HIV showed satisfactory reliability and validity. However, the domains of partnership, sexuality and medical care should generally receive more emphasis in future research on QOL assessment in patients with HIV/AIDS and the MQOL-HIV may be improved in these domains.

Comparison of sequence analysis and the INNO-LiPA HBV DR line probe assay for detection of lamivudine-resistant hepatitis B virus strains in patients under various clinical conditions

A line probe assay (INNO-LiPA HBV DR) detecting drug-resistant hepatitis B virus (HBV) strains was evaluated. Results concordant with sequence analysis were obtained with 48 of 56 serum samples from HBV-infected patients undergoing lamivudine therapy. In eight cases, additional minor subpopulations could be identified by the line probe assay.

Cytokines in surgical trauma: cholecystectomy as an example

Interleukin-1 (IL-1), tumor necrosis factor and particularly IL-6 are potent mediators of the immune and acute phase response caused by surgery and trauma. Their production can be reduced by steroids, nonsteroidal anti-inflammatory agents, nitric oxide and anti-inflammatory cytokines such as IL-4, IL-10 and IL-13. Some of the benefits of minimal invasive surgery may be due to lower cytokine levels in these procedures compared to those of conventional surgery, although this is but one factor that should be taken into account. Therefore, all surgical procedures that cause a lower systemic cytokine response are to be favored if other effects and the side effects of the surgery are equal.

[Reducing perinatal transmission by antiretroviral therapy]

In 1994 the results of Pediatric AIDS Trials Group (PACTG) Protocol 076 documented that AZT chemoprophylaxis could reduce perinatal HIV-transmission by 67%. Epidemiologic data have since confirmed the efficacy of AZT for reduction of perinatal transmission and have extended this efficacy to children of women with advanced disease, low CD4 cell count and prior AZT therapy. Additionally substantial advances have been made in the understanding of the pathogenesis of the HIV-infection, and in the treatment and monitoring of HIV-disease. These advances have resulted in changes in standard antiretroviral therapy for HIV-infected adults as well as in children and pregnant women. Antiretroviral therapy in pregnancy has two goals: optimizing therapy for the mother and prevention of perinatal transmission. It has to be taken into account that there are only a few data on short and long term effects on the fetus and newborn.

The link between exocrine pancreatic cancer and the endocrine pancreas

CONCLUSION

Experimental and human studies during 20 years of research in our laboratories point to the importance of pancreatic islets in the development of ductal-type adenocarcinomas. We believe that pancreatic cancer that develops within ducts, but more frequently within islets, derives from pancreatic stem cells that are distributed within the ductal trees and within the islets.

BACKGROUND

The histogenesis of pancreatic cancer is still debatable. Ductal, ductular, and acinar cells all have been declared the tumor progenitor cells. Our long-term human and experimental studies indicate that pancreatic ductal adenocarcinomas arise within ductal cells and islets. Supporting studies are presented in this article.

METHODS

Several human studies and experimental studies on Syrian hamsters conducted within the last 20 years were used in this article. Hamster and human islets were established, and their growth and morphologic changes were examined electron microscopically, immunohistochemically, cytogenetically, and molecular biologically.

RESULTS

Studies using the hamster pancreatic cancer model showed that most pancreatic adenocarcinomas develop within islets, most probably from stem cells, which are also believed to be the progenitor cells for tumors that develop within ducts. Studies in newly established human and hamster islets culture validated the immense potential of islet cells to differentiate and become malignant. The higher susceptibility of islet cells to become malignant could be related to their high drug-metabolizing enzymes and their high proliferation rate. Dietary studies indicate that the promoting effect of a high-fat diet on pancreatic carcinogenesis is unrelated to the energy intake, but rather is related to its effect on islet cell replication.

Comparison of line probe assay (LIPA) and sequence analysis for detection of HIV-1 drug resistance

The identification of HIV strains that are resistant to antiretroviral drugs, which emerge during a patient's therapy or are already present in infected individuals prior to treatment, is of increasing importance for the clinical management of HIV-infected persons. Two different methods were compared for the genotypic detection of resistance development in the HIV-1 reverse transcriptase (RT) gene, the commonly used sequence analysis, and the commercially available RT-line immunoprobe assay (LIPA), which can detect mutations at six separate codons of the RT gene, which are known to confer resistance to certain nucleoside inhibitors. Eighty serum samples from HIV-1-infected persons, some of whom were receiving antiretroviral therapy, were investigated in parallel by sequencing as well as by LIPA. LIPA results agreed with sequence data in the vast majority of the cases. However, in 40% of the samples, LIPA failed to yield evaluable results for one or more of the codon positions. In particular, LIPA detection rate was low at codon 41 (75%), whereas at codons 69/70, 74, 184, and 215 results were obtained from 90%-95% of the samples. A number of mutations in the vicinity of the respective codons were detected by sequencing, and these may have been responsible for the LIPA hybridization failure. There remained a number of samples, however, where no explanation for the lack of hybridization could be derived from sequence data. Our results indicate that the use of the LIPA does not eliminate the need for sequence analysis for detection of drug-resistant HIV strains.

Induction of adenocarcinoma from hamster pancreatic islet cells treated with N-nitrosobis(2-oxopropyl)amine in vitro

Our previous studies in the hamster pancreatic cancer model have indicated that pancreatic ductal adenocarcinomas derive not only from ductal/ductular cells but also from islets. To verify the presence of carcinogen-responsive cells within islets, we tested the effect of the pancreatic carcinogen N-nitrosobis(2-oxopropyl)amine (BOP) on recently established continuous hamster pancreatic islet culture. Isolated pure pancreatic islets of hamsters were treated in vitro with BOP at a concentration of 0.25 mM three times a week for 19 weeks. Each treatment week was designed as a stage. The growth of these cells, designated KL5B, was compared with untreated cultured islets, designated KL5N. As in our previous study, between 14 and 21 days of culture, exocrine and intermediary cells developed within both KL5N and KL5B islets, which were then replaced by undifferentiated cells. No differences were found in the growth patterns of KL5N and KL5B until stage 4, when KL5B cells showed accelerated cell growth and cell pleomorphism, which increased gradually at later stages of treatment. Anchorage-independent and in vivo growth did not appear until stage 19. Mutation of c-Ki-ras at codon 12 (GGT-->GAT) was detected in KL5B cells but not in KL5N cells. In vivo KL5B cells formed anaplastic invasive cancer with areas of glandular formation, overexpressed TGF-alpha and EGFR, expressed cytokeratin, vimentin, laminin and alpha-1 antitrypsin and reacted strongly with L-phytohemagglutinin and tomato lectin. Some cells within islets are responsive to the carcinogenic effects of BOP. Whether these cells represent islet cell precursors (stem cells) or malignant transdifferentiated islet cells remains to be seen.

Establishment of tumor cell culture (ILA) derived from hamster pancreatic islets treated with BOP

ILA cells were established from tumors induced by the pancreatic carcinogen N-nitrosobis(2-oxopropyl)amine (BOP) in hamster islets. The proliferation, morphology, karyotype, immunoreactivity with certain antibodies and growth factor secretion of these tumor cells were compared with the same parameters in tumor cells induced by BOP in hamster ductal cells (TAKA-1-BOP) established in a previous study. Minor differences were found in the morphology and ultrastructure of the 2 cell lines. Contrary to TAKA-1-BOP cells, ILA cells did not express cytokeratins 8.13, 13 or 18 but did express DU-PAN-2 and TAG-72, 2 known human pancreatic cancer-associated antigens. No endocrine cell markers were expressed. A significant difference also was found in the chromosomal pattern in that there were more abnormalities and marker chromosomes in ILA cells than in TAKA-1-BOP cells and the Y or X chromosomes were missing in ILA cells. ILA cells produced TGF-alpha, IGF-I, bombesin and gastrin and expressed specific binding sites for hEGF. TGF-alpha secretion from ILA cells was much greater than that from TAKA-1-BOP cells. Our results indicate that pancreatic cancer cells grown in vitro are not a single clone. We conclude that there are some genetic and biological differences between tumors arising from pancreatic duct and islets and that pancreatic ductal adenocarcinomas originating from islets have a profound malignant potential.

Port site metastases following laparoscopic cholecystectomy for unsuspected carcinoma of the gallbladder

Laparoscopic cholecystectomy is considered as the new gold standard operation for removal of the gallbladder, and has several advantages over the traditional open cholecystectomy. However, in the last few years there is an increasing number of case reports of port site metastases following laparoscopic cholecystectomy for unsuspected carcinoma of the gallbladder. Two case reports of trocar site metastases are presented, and they further highlight the concern of the role of minimal invasive surgery in the presence of unsuspected carcinoma of the gallbladder. In this review we speculate on the mechanisms which may be responsible for metastatic deposits during laparoscopic cholecystectomy and suggest certain recommendations.

Missed diaphragmatic injuries and their long-term sequelae

BACKGROUND

Blunt or penetrating truncal traumas can result in diaphragmatic rupture or injury. Because diaphragmatic defects are difficult to diagnose, those that are missed may present with latent symptoms of obstruction of herniated viscera.

METHODS

A chart review of all patients admitted with late presentations of posttraumatic diaphragmatic hernias from 1980 to 1996 was undertaken.

RESULTS

Ten patients with posttraumatic diaphragmatic hernias were treated in this specified period. There were six males and four females with a mean age of 65 years. Eight patients sustained blunt truncal traumas and two patients sustained penetrating truncal traumas. The hernias occurred in two patients on the right and in eight patients on the left side and contained the liver (n = 2), bowel (n = 10), stomach (n = 4), omentum (n = 5), or spleen (n = 1). The time until the hernias became clinically symptomatic ranged from 20 days to 28 years. In all but one patient, either routine chest roentgenograms or upper gastrointestinal contrast studies were diagnostic. All 10 patients underwent laparotomy (n = 9) or thoracotomy (n = 2) with direct repair of the diaphragmatic defect. One patient died 3 days after the operation, representing a mortality of 10%; the morbidity was 30%.

CONCLUSION

Initial recognition and treatment of diaphragmatic rupture or injury is important in avoiding long-term sequelae.

Cyclic hexapeptides related to somatostatin. Synthesis and biological testing

As a continuation of our program to study the structure-function relationship of the peptide hormone somatostatin, we report the synthesis and biological potencies of a series of cyclic hexapeptide analogs related to somatostatin. The parent peptide of this series was designed by Veber and coworkers, c[-Pro6-Phe7-D-Trp8-Lys9-Thr10-Phe11-], and has been reported to be superactive in the inhibition of the release of growth hormone. (The superscript numbers refer to the positions of residues in native somatostatin). The series of analogs has been designed to examine the role of the so-called bridging region, Phe11-Pro6, which has been postulated to be important in maintaining the proper conformation of the biologically active tetrapeptide, Phe-D-Trp-Lys-Thr. We have incorporated peptidomimetics and the retro-inverso modification into the bridging region of the molecule, with the aim of affecting the conformational preferences found in the parent peptide. Results from the biological assay--in vitro inhibition of growth hormone--and the conformational analysis (adjoining paper) of our analogs will provide insight into the relationship between structure and biological activity of somatostatin.

Peptide sweeteners. 6. Structural studies on the C-terminal amino acid of L-aspartyl dipeptide sweeteners

Stereochemical and structural aspects of the variations in the C-terminal residue of L-aspartyl-L-phenylalanine methyl ester have been investigated. Novel configurational analogues such as L-aspartyl-D-alanine benzyl ester and L-aspartyl-D-alpha-aminobutyric acid benzyl ester were found to be sweet. In addition, chiral and achiral alpha, alpha-dialkylglycine and alpha-aminocycloalkanecarboxylic acids were incorporated into the dipeptides. The L-aspartic acid based dipeptide derivatives of alpha-aminoisobutyric acid methyl ester, alpha-aminocyclopropanecarboxylic acid methyl ester, alpha-aminocyclobutanecarboxylic acid methyl ester, and alpha-aminocyclopentanecarboxylic acid methyl ester are sweet. Dipeptides with alpha-aminocyclohexanecarboxylic acid methyl ester and alpha-aminocycloheptanecarboxylic acid methyl ester are bitter, whereas the analogues with alpha-aminocyclooctanecarboxylic acid methyl ester, alpha, alpha-diethylglycine methyl ester, and alpha-aminoisobutyric acid benzyl ester are tasteless. Aspects on chirality and effective volume of the C-terminal residue are discussed and correlated with taste.