Antibodies to S2 domain of SARS-CoV-2 spike protein in Moderna mRNA vaccinated subjects sustain antibody-dependent NK cell-mediated cell cytotoxicity against Omicron BA.1

Vaccination with the primary two-dose series of SARS-CoV-2 mRNA protects against infection with the ancestral strain, and limits the presentation of severe disease after re-infection by multiple variants of concern (VOC), including Omicron, despite the lack of a strong neutralizing response to these variants. We compared antibody responses in serum samples collected from mRNA-1273 (Moderna) vaccinated subjects to identify mechanisms of immune escape and cross-protection. Using pseudovirus constructs containing domain-specific amino acid changes representative of Omicron BA.1, combined with domain competition and RBD-antibody depletion, we showed that RBD antibodies were primarily responsible for virus neutralization and variant escape. Antibodies to NTD played a less significant role in antibody neutralization but acted along with RBD to enhance neutralization. S2 of Omicron BA.1 had no impact on neutralization escape, suggesting it is a less critical domain for antibody neutralization; however, it was as capable as S1 at eliciting IgG3 responses and NK-cell mediated, antibody-dependent cell cytotoxicity (ADCC). Antibody neutralization and ADCC activities to RBD, NTD, and S1 were all prone to BA.1 escape. In contrast, ADCC activities to S2 resisted BA.1 escape. In conclusion, S2 antibodies showed potent ADCC function and resisted Omicron BA.1 escape, suggesting that S2 contributes to cross-protection against Omicron BA.1. In line with its conserved nature, S2 may hold promise as a vaccine target against future variants of SARS-CoV-2.

Direct mosquito feedings on dengue-2 virus-infected people reveal dynamics of human infectiousness

Dengue virus (DENV) transmission from humans to mosquitoes is a poorly documented, but critical component of DENV epidemiology. Magnitude of viremia is the primary determinant of successful human-to-mosquito DENV transmission. People with the same level of viremia, however, can vary in their infectiousness to mosquitoes as a function of other factors that remain to be elucidated. Here, we report on a field-based study in the city of Iquitos, Peru, where we conducted direct mosquito feedings on people naturally infected with DENV and that experienced mild illness. We also enrolled people naturally infected with Zika virus (ZIKV) after the introduction of ZIKV in Iquitos during the study period. Of the 54 study participants involved in direct mosquito feedings, 43 were infected with DENV-2, two with DENV-3, and nine with ZIKV. Our analysis excluded participants whose viremia was detectable at enrollment but undetectable at the time of mosquito feeding, which was the case for all participants with DENV-3 and ZIKV infections. We analyzed the probability of onward transmission during 50 feeding events involving 27 participants infected with DENV-2 based on the presence of infectious virus in mosquito saliva 7-16 days post blood meal. Transmission probability was positively associated with the level of viremia and duration of extrinsic incubation in the mosquito. In addition, transmission probability was influenced by the day of illness in a non-monotonic fashion; i.e., transmission probability increased until 2 days after symptom onset and decreased thereafter. We conclude that mildly ill DENV-infected humans with similar levels of viremia during the first two days after symptom onset will be most infectious to mosquitoes on the second day of their illness. Quantifying variation within and between people in their contribution to DENV transmission is essential to better understand the biological determinants of human infectiousness, parametrize epidemiological models, and improve disease surveillance and prevention strategies.

Development and validation of a vero cell-based suspension method for the detection of Zika virus

OBJECTIVE.

To develop and validate a cell suspension method using Vero 76 cells for culturing Zika virus (ZIKV) based on infection of detached freshly seeded cells.

MATERIAL AND METHODS.

Three different multiplicities of infection of ZIKV were used to develop and compare this novel method to the standard confluent cell monolayer method. In addition, we preliminary validated the cell suspension method using well-characterized ZIKV positive and negative clinical samples. The standard confluent cell monolayer method was used as the reference method, and viral isolation was confirmed by a ZIKV-specific RT-PCR. The sensitivity and its 95% confidence intervals for the cell suspension method were estimated. Also, a technical comparison of the cell suspension method against the cell monolayer method was performed.

RESULTS.

Our findings suggested that both the viral load and replication of ZIKV were comparable between both monolayer- and suspension-infection methods. Although both methods were suitable for culturing and isolating ZIKV, the cell suspension method was easier, cheaper, and quicker as well as a sensitive isolation technique. The cell suspension method was significantly more sensitive in detecting Zika in inconclusive cases by RT-PCR, with a fourfold increase compared to the confluent cell monolayer method.

CONCLUSION.

The cell suspension method has the potential to be an effective method for cultivating and isolating ZIKV and its application is potentially useful in both research and clinical settings.

Quantifying heterogeneities in arbovirus transmission: Description of the rationale and methodology for a prospective longitudinal study of dengue and Zika virus transmission in Iquitos, Peru (2014-2019)

Current knowledge of dengue virus (DENV) transmission provides only a partial understanding of a complex and dynamic system yielding a public health track record that has more failures than successes. An important part of the problem is that the foundation for contemporary interventions includes a series of longstanding, but untested, assumptions based on a relatively small portion of the human population; i.e., people who are convenient to study because they manifest clinically apparent disease. Approaching dengue from the perspective of people with overt illness has produced an extensive body of useful literature. It has not, however, fully embraced heterogeneities in virus transmission dynamics that are increasingly recognized as key information still missing in the struggle to control the most important insect-transmitted viral infection of humans. Only in the last 20 years have there been significant efforts to carry out comprehensive longitudinal dengue studies. This manuscript provides the rationale and comprehensive, integrated description of the methodology for a five-year longitudinal cohort study based in the tropical city of Iquitos, in the heart of the Peruvian Amazon. Primary data collection for this study was completed in 2019. Although some manuscripts have been published to date, our principal objective here is to support subsequent publications by describing in detail the structure, methodology, and significance of a specific research program. Our project was designed to study people across the entire continuum of disease, with the ultimate goal of quantifying heterogeneities in human variables that affect DENV transmission dynamics and prevention. Because our study design is applicable to other Aedes transmitted viruses, we used it to gain insights into Zika virus (ZIKV) transmission when during the project period ZIKV was introduced and circulated in Iquitos. Our prospective contact cluster investigation design was initiated by detecttion of a person with a symptomatic DENV infection and then followed that person's immediate contacts. This allowed us to monitor individuals at high risk of DENV infection, including people with clinically inapparent and mild infections that are otherwise difficult to detect. We aimed to fill knowledge gaps by defining the contribution to DENV transmission dynamics of (1) the understudied majority of DENV-infected people with inapparent and mild infections and (2) epidemiological, entomological, and socio-behavioral sources of heterogeneity. By accounting for factors underlying variation in each person's contribution to transmission we sought to better determine the type and extent of effort needed to better prevent virus transmission and disease.

Correction: Bacillus anthracis Spore Surface Protein BclA Mediates Complement Factor H Binding to Spores and Promotes Spore Persistence

[This corrects the article DOI: 10.1371/journal.ppat.1005678.].

Characterization of Bacillus anthracis persistence in vivo

Pulmonary exposure to Bacillus anthracis spores initiates inhalational anthrax, a life-threatening infection. It is known that dormant spores can be recovered from the lungs of infected animals months after the initial spore exposure. Consequently, a 60-day course antibiotic treatment is recommended for exposed individuals. However, there has been little information regarding details or mechanisms of spore persistence in vivo. In this study, we investigated spore persistence in a mouse model. The results indicated that weeks after intranasal inoculation with B. anthracis spores, substantial amounts of spores could be recovered from the mouse lung. Moreover, spores of B. anthracis were significantly better at persisting in the lung than spores of a non-pathogenic Bacillus subtilis strain. The majority of B. anthracis spores in the lung were tightly associated with the lung tissue, as they could not be readily removed by lavage. Immunofluorescence staining of lung sections showed that spores associated with the alveolar and airway epithelium. Confocal analysis indicated that some of the spores were inside epithelial cells. This was further confirmed by differential immunofluorescence staining of lung cells harvested from the infected lungs, suggesting that association with lung epithelial cells may provide an advantage to spore persistence in the lung. There was no or very mild inflammation in the infected lungs. Furthermore, spores were present in the lung tissue as single spores rather than in clusters. We also showed that the anthrax toxins did not play a role in persistence. Together, the results suggest that B. anthracis spores have special properties that promote their persistence in the lung, and that there may be multiple mechanisms contributing to spore persistence.

Activation of the classical complement pathway by Bacillus anthracis is the primary mechanism for spore phagocytosis and involves the spore surface protein BclA

Interactions between spores of Bacillus anthracis and macrophages are critical for the development of anthrax infections, as spores are thought to use macrophages as vehicles to disseminate in the host. In this study, we report a novel mechanism for phagocytosis of B. anthracis spores. Murine macrophage-like cell line RAW264.7, bone marrow-derived macrophages, and primary peritoneal macrophages from mice were used. The results indicated that activation of the classical complement pathway (CCP) was a primary mechanism for spore phagocytosis. Phagocytosis was significantly reduced in the absence of C1q or C3. C3 fragments were found deposited on the spore surface, and the deposition was dependent on C1q and Ca(2+). C1q recruitment to the spore surface was mediated by the spore surface protein BclA, as recombinant BclA bound directly and specifically to C1q and inhibited C1q binding to spores in a dose-dependent manner. C1q binding to spores lacking BclA (ΔbclA) was also significantly reduced compared with wild-type spores. In addition, deposition of both C3 and C4 as well as phagocytosis of spores were significantly reduced when BclA was absent, but were not reduced in the absence of IgG, suggesting that BclA, but not IgG, is important in these processes. Taken together, these results support a model in which spores actively engage CCP primarily through BclA interaction with C1q, leading to CCP activation and opsonophagocytosis of spores in an IgG-independent manner. These findings are likely to have significant implications on B. anthracis pathogenesis and microbial manipulation of complement.

ABCA4 mutations and discordant ABCA4 alleles in patients and siblings with bull's-eye maculopathy

AIM

To determine the frequency and nature of mutations in the gene ABCA4 in a cohort of patients with bull's-eye maculopathy (BEM).

METHODS

A panel of 49 subjects (comprising 40 probands/families, 7 sibling pairs and a set of three sibs) with BEM, not attributable to toxic causes, was ascertained. Blood samples from each patient were used to extract genomic DNA, with subsequent mutation screening of the entire coding sequence of ABCA4, using single-strand conformational polymorphism (SSCP) analysis and direct sequencing.

RESULTS

Fourteen probands (35%) were found to have a potentially disease-causing ABCA4 sequence variant on at least one allele. Three patients had a Gly1961Glu missense mutation, the most common variant in Stargardt disease (STGD), with 2 of these subjects having a macular dystrophy (MD) phenotype and a second ABCA4 variant previously associated with STGD. The second most common STGD mutation, Ala1038Val, was seen in one patient with cone-rod dystrophy (CORD). Five novel ABCA4 variants were detected. Two sibships were identified with a similar intra-familial phenotype but discordant ABCA4 variants.

CONCLUSIONS

Variations in the ABCA4 gene are common in BEM. Two sibships showed discordant ABCA4 variants. One of these sibships illustrates that ABCA4 variants can be identified in families that have another molecular cause for their disease, due to the high prevalence of ABCA4 disease alleles in the population. The discordance evident in the second sibship may yet also be a chance finding in families with macular disease of another genetic cause, or it may represent a complex mode of inheritance determined/modified by the combination of ABCA4 alleles.

Administration of adrenocorticotropic hormone during chicken embryonic development prematurely induces pituitary growth hormone cells

Treatment of fetal rats and embryonic chickens with exogenous glucocorticoids induces premature GH cell differentiation. However, it is unknown whether the developing adrenal gland is capable of mounting this response autonomously. The present study determined whether stimulation of the adrenal gland in developing chicken embryos through administration of ACTH could induce a premature increase in GH cells. We found that plasma corticosterone and ACTH levels increased between embryonic day (e) 11 and e17, consistent with GH cell (somatotroph) ontogeny. Injection of ACTH into eggs on e9, e10, or e11 increased somatotrophs on e14. In contrast, thyroid-stimulating hormone, CRH, alpha-MSH, GHRH, and TRH were ineffective. Culture of e11 pituitary cells with ACTH failed to induce somatotrophs, suggesting an indirect action of ACTH on GH cells in vivo. Intravenous administration of ACTH dramatically increased plasma levels of corticosterone within 1 h and increased the percentage of pituitary somatotrophs within 24 h. Although ACTH administration increased the relative abundance of pituitary GH cells, there was no effect on plasma levels of GH, IGF-I, or IGF-II, or in hepatic expression of IGF-I or IGF-II mRNA. We conclude that ACTH administration can increase the population of GH cells in the embryonic pituitary. However, this treatment alone does not lead to downstream activation of hepatic IGF production. These findings indicate that the embryonic adrenal gland, and ultimately anterior pituitary corticotrophs, may function to regulate pituitary GH cell differentiation during embryonic development.

HIV- I Nef severely impairs thymocyte development and peripheral T-cell function by a CD4-independent mechanism

Nef is a regulatory protein of the human and simian immunodeficiency viruses (HIV and SIV) whose role in infection and the viral life cycle are not fully understood. In T-lymphocytes Nef down-regulates cell-surface CD4, and has been implicated in an increase in infectivity at low primary viral isolate titres. Additionally, the SIV nef gene is necessary for viraemia and AIDS-like pathogenesis in rhesus macaques. We report here in an in vivo murine transgenic model that thymocyte and T-cell-specific nef gene expression results in a marked decrease in thymic cellularity from 16 days post coitus. This reduction in thymocyte cell number is independent of CD4 expression and Nef-induced CD4 down-regulation, but can be restored by expressing a constitutively active p56lckF505 gene. Functional analyses have revealed a severe decrease in thymocyte and T-cell proliferation in response to both T-cell-receptor- and mitogen-mediated stimuli. In addition, a significant proportion of Nef-expressing peripheral T-cells display cell-surface characteristics associated with cellular activation. These results suggest that Nef expression in developing thymocytes can severely reduce the regeneration capacity of the immune system, whereas expression in mature T-cells dramatically decreases their potential to respond to antigen. With the recent recognition of a persistently high viral load in HIV-infected individuals, these findings have important implications for the mechanism of the progressive deterioration of the immune system that leads to AIDS.

GABAergic neurons in the lateral superior olive of the hamster are distinguished by differential expression of gad isoforms during development

Gamma-aminobutyric acid (GABA) is an inhibitory neurotransmitter that is synthesized by two isoforms of glutamic acid decarboxylase (GAD), GAD65 and GAD67. Using in situ hybridization and immunocytochemical techniques in hamsters, we investigated the postnatal development of GAD isoforms within the lateral superior olive (LSO) where GABAergic neurons form part of a descending efferent projection to the cochlea. In the neonatal hamster LSO, GAD67 immunoreactivity, GAD67 transcript labeling, and intense GABA immunostaining are at low levels. However, robust GAD65 mRNA expression is found throughout the LSO during the early postnatal period. The neonatal GABAergic expression patterns are in stark contrast to the adult where the LSO has robust GAD67 mRNA expression and weak GAD65 mRNA expression. Cells exhibiting intense GABA immunolabeling were also found in the same LSO locations as robust GAD67 mRNA expression and intense GAD67 immunoreactivity. Additionally, GAD67-positive cells in the LSO were retrogradely labeled from the cochlea confirming that these cells are a part of the lateral olivocochlear system. The late onset of GAD67 expression and intense GABA immunoreactivity in LSO neurons are consistent with the relatively late maturation of the lateral olivocochlear neurons inferred from previous studies. During development, these data lead us to conclude that the GABAergic portion of the lateral olivocochlear system is distinguished by preferential GAD67 expression, intense GABA immunoreactivity, and relatively late postnatal onset.

Clinical characterisation of a family with retinal dystrophy caused by mutation in the Mertk gene

BACKGROUND/AIM

MERTK, a tyrosine kinase receptor protein expressed by the retinal pigment epithelium (RPE), is mutated in both rodent models and humans affected by retinal disease. This study reports a survey of families for Mertk mutations and describes the phenotype exhibited by one family.

METHODS

96 probands with retinal dystrophy, consistent with autosomal recessive segregation, were screened by direct sequencing. A family homozygous for a likely null allele was investigated clinically.

RESULTS

A novel frame shifting deletion was identified in one of 96 probands. Other polymorphisms were detected. The deletion allele occurred on both chromosomes of four affected family members. Electrophysiology demonstrated early loss of scotopic and macular function with later loss of photopic function. Visual acuities and visual fields were preserved into the second decade. Perception of light vision was present in a patient in the fourth decade. A "bull's eye" appearance and a hyperautofluorescent lesion at the central macula were consistent clinical findings.

CONCLUSIONS

Mutations in Mertk are a rare cause of ARRP in humans. The study extends the phenotypic characteristics of this retinal dystrophy and shows distinctive clinical signs that may improve its clinical identification. The moderate severity and presence of autofluorescence implies that outer segment phagocytosis is not entirely absent.

Fluorescence in-situ hybridisation on biopsies from clam ileocystoplasties and on a clam cancer

The incidence of carcinoma following an enterocystoplasty increases with time and is a major concern after such procedures. The aim of this study was to investigate genetic instability (in the form of numerical chromosomal aberrations) at the enterovesical anastomosis in patients who had undergone a clam ileocystoplasty using fluorescent in-situ hybridisation (FISH). Fluorescent in-situ hybridisation was performed on touch preparation samples prepared from fresh endoscopic biopsies obtained from the enterovesical anastomosis and native bladder remnant (control specimens) of 15 patients who had undergone a clam ileocystoplasty. Fluorescent in-situ hybridisation was also performed on one squamous cell cancer specimen. Significant aneusomic changes were found at the enterovesical anastomosis in all 15 patients. Alterations in chromosome 18 copy number were the most frequent abnormal finding (trisomy 18, n=8; monosomy 18, n=7). Nine patients were monosomic for chromosome 9. Isolated monosomy 8 and trisomy 8 were each found in one patient. The control specimens were all normal. An unusually high incidence of polysomic cells was found in the clam tumour specimen, reflecting the aggressive nature of this cancer. Chromosomal numerical abnormalities occur at the enterovesical anastomosis following a clam ileocystoplasty and chromosome 18 appears to be a particularly good marker of genetic instability. The results of this study indicate that morphologically normal tissue obtained from the enterovesical anastomosis displays evidence of chromosomal instability that may predispose to tumour formation. However, further prospective, blinded, longitudinal studies are required to establish whether predetermined FISH signal patterns in enterocystoplasty cells in urine or obtained by biopsy predict the presence or absence of tumour.

Functional characterisation and serial imaging of abnormal fundus autofluorescence in patients with retinitis pigmentosa and normal visual acuity

AIM

To characterise and monitor abnormal fundus autofluorescence (AF) in patients with retinitis pigmentosa (RP) who have good visual acuity.

METHODS

21 patients with a clinical diagnosis of RP were examined. All had rod-cone dystrophy (ISCEV standard electroretinograms (ERGs)), visual acuity of 6/9 or better, and manifested a parafoveal ring of high density fundus AF. Repeat AF imaging was performed after periods of between 2 years and 5 years in 12 patients. Pattern ERG (PERG) and multifocal ERG (mfERG) were performed in 20 cases. Visual fields (VF), photopic and scotopic fine matrix mapping and small field PERGs were performed in representative cases.

RESULTS

The rings of high density AF varied in size between patients (from 4 degrees -16 degrees diameter). MfERGs showed relative preservation over the central macular area, correlating with the size of AF ring and with PERG and psychophysical data. Progressive constriction of the AF ring was demonstrated at follow up in three patients. Serial PERG, mfERG, and VFs, performed in one of these cases, showed evidence of deterioration concordant with ring constriction.

CONCLUSIONS

High density rings of AF, seen in some patients with RP with good visual acuity, demarcate areas of preserved central photopic function. MfERGs correlate with the area encircled by high density AF and the PERG data. The size of the ring of AF can show progressive constriction accompanied by increasing macular dysfunction.

Does smoking influence the type of age related macular degeneration causing visual impairment?

AIMS

To assess the influence of smoking on the type of age related macular degeneration (AMD) lesion causing visual impairment in a large cohort of patients with AMD at a tertiary referral UK centre.

METHODS

Prospective, observational, cross sectional study to analyse smoking data on 711 subjects, of western European origin, in relation to the type of AMD lesion present. Colour fundus photographs were graded according to a modified version of the international classification. Multiple logistic regression analysis was performed, adjusting for age and sex using the statistical package SPSS ver 9.0 for Windows. chi(2) tests were also used to assess pack year and ex-smoker data.

RESULTS

578 subjects were graded with neovascular AMD and 133 with non-neovascular AMD. There was no statistically significant association found between smoking status or increasing number of pack years and type of AMD lesion. The odds of "current smokers" compared to "non-smokers" developing neovascular rather than non-neovascular AMD when adjusted for age and sex was 1.88 (95% CI: 0.91 to 3.89; p = 0.09).

CONCLUSIONS

Smoking is known to be a risk factor for AMD and this study suggests that smokers are at no more risk of developing neovascular than atrophic lesions.

Hepatocyte growth factor/scatter factor and prostate cancer: a review

Men who die from prostate cancer do so from uncontrolled metastatic disease. A better understanding of the mechanisms involved in the progression and metastasis of prostate cancer may lead to novel therapeutic approaches to prevent its natural progression. Hepatocyte Growth Factor / Scatter factor (HGF/SF) has been demonstrated to elicit a number of key functions in numerous tissues that are important in the progression, invasion and metastasis of cancer. Studies have demonstrated that the activity of HGF/SF and its receptor c-Met are linked to disease progression in numerous cancers. However, research into these functions, which include activities as a mitogen, a motogen and an anti-apoptotic and angiogenic factor in prostate cancer are limited. This article reviews the published evidence of the roles HGF/SF plays in prostate cancer progression and highlights the clinical and therapeutic potential of research into this pleiomorphic cytokine.

An atypical phenotype of macular and peripapillary retinal atrophy caused by a mutation in the RP2 gene

AIMS

To determine the molecular basis and describe the phenotype of an atypical retinal dystrophy in a family presenting with bilateral, progressive central visual loss.

METHODS

Family members were examined. Investigations included Goldman perimetry, electrophysiology, and autofluorescence imaging. Candidate gene screening was performed using SSCP and sequence analysis. The proband's lymphoblastoid cells were examined for protein expression.

RESULTS

Fundal examination of the proband, his mother, and brother revealed peripapillary and macular atrophy. Autosomal dominant retinal dystrophy was suspected, but less severe disease in the mother led to screening for mutations in X linked genes. A 4 bp microdeletion in exon 3 of the RP2 gene, segregating with disease, was identified. No RP2 protein expression was detected.

CONCLUSION

The distinct phenotype in this family, caused by this frameshifting mutation in RP2, broadens the phenotypic spectrum of X linked retinitis pigmentosa. The absence of RP2 protein suggests that loss of protein function and not novel gain of function could account for the atypical phenotype. A definitive diagnosis of X linked retinitis pigmentosa permits appropriate genetic counselling with important implications for other family members. Clinicians should have a low threshold for screening RP2 in families with retinal dystrophy, including posterior retinal disease, not immediately suggestive of X linked inheritance.

Ontogeny of the hypothalamo-pituitary-adrenocortical axis in the chicken embryo: a review

The embryo of the domestic fowl (Gallus domesticus) tenders one distinctive advantage over general mammalian models for investigating the development of the hypothalamo-pituitary-adrenocortical (HPA) axis. This is the relative simplicity with which the embryonic endocrine environment can be influenced without confounding maternal influences. The ease of direct manipulation of the embryonic endocrine system has facilitated analysis of the development and function of the HPA axis in the chick embryo. As the chick embryo develops, functional activation of the adrenal gland is regulated at three different levels: the adrenal gland itself, the anterior pituitary, and the hypothalamus. The adrenal gland appears capable of independent secretion of glucocorticoids from day 8 until shortly after day 14 of embryonic development, at which point the pituitary influences adrenocortical activity. Around the same age, the hypothalamic level of control also begins. The information covered in this review will describe the major steps in the development of the HPA axis in the chicken embryo and show that the chicken has an emblematic HPA neuroendocrine axis.

Somatostatin analogs in oncology: a look to the future

In the past 15 years considerable advances have been made in our understanding of the molecular pharmacology of the mechanisms whereby somatostatin and its analogs mediate their direct and indirect antineoplastic effects. However, some important issues remain to be resolved, in particular the functional roles of the individual somatostatin receptors (SSTR-1-5) in tumor tissue and up- or downregulation of the hSSTRs with prolonged administration of somatostatin analogs. Answers to these questions are essential before we can maximize the therapeutic efficacy of somatostatin analogs in cancer. For example, is continuous administration more or less effective than intermittent therapy? The role of somatostatin analogs in the management of acromegaly and to a lesser extent neuroendocrine tumors is firmly established. The development of depot preparations of all 3 somatostatin analogs currently available for clinical use will undoubtedly improve both patient compliance and quality of life in patients with these conditions. There are only likely to be minor differences in the therapeutic efficacy of octreotide, lanreotide and vapreotide since all three analogs exert the majority of their antineoplastic effects via hSSTR-2 and hSSTR-5 and at the end of the day, price may well dictate which of these drugs oncologists use to provide symptomatic palliation of acromegaly and neuroendocrine tumors. Apart from some notable exceptions, somatostatin analog therapy has proven to be very disappointing in the management of advanced malignancy. Improvements in the management of solid tumors are likely to come only from combination therapy of somatostatin analogs with cytotoxic agents or other hormones in both advanced malignancy and in the adjuvant setting. Clinical trials with clear-cut objective outcome measures and health-related quality of life assessment are needed to evaluate the therapeutic efficacy of combination treatment in advanced malignancy and as an adjuvant to surgery. Particular attention needs to be paid to possible adverse effects of somatostatin analog therapy on the immune response to cancer. Further studies are required to establish whether the adverse effects of somatostatin analog therapy alone or in combination with cytotoxics or other hormones can be reversed with appropriate immunomodulatory treatment. Targeted somatostatin analog radiotherapy and chemotherapy are currently being investigated and the results of these studies are awaited with interest. Novel approaches using combinations of somatostatin analogs with antiangiogenic drugs or gene therapy are of particular interest and may provide important advances in the management of cancer in the not too distant future.

Awake intubation made easy and acceptable

This study examined the efficacy of a technique of administration of lignocaine 2% (with 1:200,000 adrenaline) to the nose, pharynx and larynx. A simple device constructed from a 22 gauge Optiva cannula attached to a medical oxygen supply via green "bubble" tubing and the barrel of a 3 ml syringe, similar to that described by Mackenzie, was used to administer aerosolized lignocaine initially via the nose and subsequently via a nasopharyngeal airway. Ten unsedated, unpremedicated volunteers were intubated. The mean time from the start of the administration of lignocaine to confirmation of placement of the endotracheal tube was 12 minutes (range 8 to 19 minutes). Intubating conditions were good and the procedure was well tolerated in all subjects. The mean dose of lignocaine was 4.8 mg.kg-1 (range 2.7 to 6.9 mg.kg-1) and plasma concentrations were well below toxic levels (highest concentration 3.12 mg.l-1). There was good haemodynamic stability and no episode of oxyhaemoglobin desaturation.

Drug therapy for non-variceal upper gastrointestinal bleeding. Assessment of options

The efficacy of somatostatin and octreotide have been widely studied in the control of bleeding from oesophageal varices. It has also been suggested that these drugs may be useful for the control of non-variceal upper gastrointestinal (UGI) bleeding, including that from peptic ulcers. In approximately 80% of patients presenting with non-variceal UGI bleeding, haemorrhage ceases spontaneously and does not recur. However, the remaining 20% of patients require active treatment. Results from recent studies have indicated that somatostatin is an effective treatment for the control of non-variceal UGI bleeding in high-risk patients, i.e. those in whom haemorrhage does not cease spontaneously or is likely to recur. In contrast there is no good evidence available at present to support a role for octreotide, histamine (H(2) antagonists) or proton pump inhibitors in this indication. The efficacy of somatostatin in controlling bleeding in patients with non-variceal UGI bleeding at high risk of mortality upon admission, or rebleeding following endoscopy, coupled with an excellent safety and tolerability profile, suggests it may be a valuable therapeutic option in the management of non-variceal bleeding.

Do alterations in the rate of gastric emptying after injection sclerotherapy for oesophageal varices play any role in the development of portal hypertensive gastropathy?

Bleeding from portal hypertensive gastropathy (PHG) has been estimated to account for up to 30% of all upper gastrointestinal haemorrhage in patients with cirrhosis and portal hypertension. Although portal hypertension seems to be an essential prerequisite, the precise mechanisms responsible for the development of PHG are unknown. The aim of this study was to examine the role of injection sclerotherapy of oesophageal varices in the development of PHG. Gastric emptying was studied using a radionuclide test meal with the emptying characteristics of a slow liquid in 57 patients with cirrhosis and/or portal hypertension (median age 53 yrs), of whom 34 had received injection sclerotherapy for their oesophageal varices and 20 normal healthy volunteers (median age 42 yrs). As vagal damage is associated with more rapid emptying of liquids, despite hold up of solids, this technique might be expected to demonstrate such damage if gastric emptying was accelerated. The results indicated that there was no difference in the rate of gastric emptying between normal healthy volunteers and portal hypertensive patients. However, patients who had received injection sclerotherapy emptied their stomachs faster than those who had not (p < 0.05). Furthermore, the speed of gastric emptying correlated directly with the number of injections (r = 0.41; p = 0.02) and the volume of sclerosant injected (r = 0.39; p = 0.03). These observations suggest that injection sclerotherapy for oesophageal varices results in disturbances of gastric emptying that may contribute to the pathogenesis of portal hypertensive gastropathy.

Grading of benign prostatic obstruction can predict the outcome of transurethral prostatectomy

PURPOSE

We investigate whether urodynamic grading of benign prostatic obstruction and detrusor contractility predicts the outcome of transurethral prostatectomy.

MATERIALS AND METHODS

A total of 53 patients who were suitable candidates for transurethral prostatectomy completed an assessment protocol before and 3 months after surgery, which included International Prostate Symptom Score, uroflowmetry, ultrasonography (prostatic size and residual urine volume) and standard pressure flow study. The results of the pressure flow study were analyzed to grade obstruction (unequivocal, equivocal or no obstruction) and detrusor contractility (weak or normal) using our simplified pressure flow nomogram.

RESULTS

Analysis of the pressure flow study data demonstrated that the efficiency of detrusor contraction was weak in 6 of 27 men with unequivocal, 11 of 23 with equivocal and 2 of 3 with no obstruction. Treatment outcome was significantly better in patients with unequivocal obstruction and normal detrusor contractility. Treatment failure occurred in 80% of patients with equivocal obstruction and impaired detrusor contractility, and 100% of the unobstructed group. Urodynamic grading of obstruction and detrusor contractility predicted treatment outcome with a sensitivity of 87%, specificity 93% and positive predictive value 95%.

CONCLUSIONS

Urodynamic grading of benign prostatic obstruction and detrusor contractility can reliably predict treatment outcome and, therefore, enable the urologist to identify a subgroup of patients who would not benefit from surgery.

Hepatosplanchnic haemodynamics and renal blood flow and function in rats with liver failure

BACKGROUND

Massive liver necrosis, characteristic of acute liver failure, may affect hepatosplanchnic haemodynamics, and contribute to the alterations in renal haemodynamics and function.

AIMS

To investigate the relation between hepatosplanchnic haemodynamics, including portal systemic shunting, and renal blood flow and function in rats with acute liver failure.

METHODS

Liver failure was induced in male Wistar rats by intraperitoneal injection of 1.1 g/kg of D(+)-galactosamine hydrochloride. The parameters assessed included; systemic, hepatosplanchnic, and renal blood flow (57Co microsphere method); portal-systemic shunting and intrarenal shunting (consecutive intrasplenic, intraportal, or renal arterial injections of 99mTc methylene diphosphonate and 99mTc albumin microspheres); arterial blood pressure and portal pressure; renal function; and liver function (liver function tests and 14C aminopyrine breath test).

RESULTS

Progressive liver dysfunction was accompanied by the development of a hyperdynamic circulation, a highly significant decrease in renal blood flow and function, and an increase in intrarenal shunting 36, 42, and 48 hours after administration of D-galactosamine. The alterations in renal blood flow and function were accompanied by significant increases in portal pressure, portal venous inflow, and intrahepatic portal systemic shunting in galactosamine treated rats compared with controls. There was a significant correlation between changes in renal blood flow and changes in portal pressure, intrahepatic portal systemic shunting, and deterioration in liver function (r = 0.8, p < 0.0001).

CONCLUSIONS

The results of this study suggest that both increased intrahepatic portal systemic shunting and hepatocyte impairment may contribute to alterations in renal haemodynamics and function.

Pharmacokinetics of octreotide in patients with cirrhosis and portal hypertension; relationship between the plasma levels of the analogue and the magnitude and duration of the reduction in corrected wedged hepatic venous pressure

In healthy subjects octreotide is largely metabolised by the liver suggesting that the plasma half-life of the somatostatin analogue may be prolonged in patients with hepatic dysfunction. The aim of this study was therefore (a) to determine the pharmacokinetics of octreotide following its subcutaneous injection in 6 patients with cirrhosis and portal hypertension and (b) compare the magnitude and duration of the effects of intravenous administration of 250 micrograms somatostatin and 50 micrograms octreotide on corrected wedged hepatic venous pressure (WHVP) and to relate the findings to the plasma levels of the analogue 1 h after administration in 13 patients with cirrhosis and portal hypertension. Following subcutaneous administration of 50 micrograms octreotide the circulating half life (range 2.4 to 4.79 h) was prolonged whereas the clearance (range 2.101 to 4.775 L/h) was decreased compared to healthy controls. Intravenous bolus administration of 250 micrograms somatostatin or 50 micrograms octreotide resulted in a reduction in WHVP of approximately the same magnitude and duration despite appreciable quantities of the analogue in the blood 1 h after administration (1944 +/- 226 pg/ml). These results indicate that the circulating half-life of octreotide is prolonged in cirrhotics suggesting that the dosage regimens should be modified in such patients to avoid accumulation of the analogue in the blood which may result in undesirable side-effects or toxicity. Furthermore, since the magnitude and duration of the reduction in WHVP elicited by IV octreotide is similar to that observed with somatostatin, the analogue, like the native hormone, must be administered by continuous IV infusion to produce a sustained response and hence a therapeutic effect in the management of acute variceal bleeding.

Somatostatin in the treatment of non-variceal upper gastrointestinal bleeding

The efficacies of somatostatin and octreotide have been widely studied in the control of bleeding from oesophageal varices. It has also been suggested that these drugs may be useful for the control of non-variceal upper gastrointestinal (UGI) bleeding, including that from peptic ulcers. In approximately 80% of patients presenting with non-variceal UGI bleeding, haemorrhage ceases spontaneously and does not recur. However, the remaining 20% of patients require active treatment. Results from recent studies have indicated that somatostatin is an effective treatment for the control of non-variceal UGI bleeding in high-risk patients, i.e. those in whom haemorrhage does not cease spontaneously or is likely to recur. In contrast there is no good evidence available at present to support a role for octreotide in this indication. The efficacy of somatostatin in controlling bleeding in patients with non-variceal UGI bleeding at high risk of mortality upon admission, or rebleeding following endoscopy, coupled with an excellent safety and tolerability profile, suggests that it may be a valuable therapeutic option in the management of non-variceal bleeding.

Development of analogues: successes and failures

The search for new pharmaceutical treatments has led to the isolation of products from a range of natural sources. Analogues synthesized from these products may possess an improved therapeutic effect over their natural counterparts. Two natural peptides, vasopressin and somatostatin, possess pronounced in vivo effects, so do their analogues terlipressin and octreotide. Vasopressin is a powerful vasopressor, reducing portal pressure, and has been used to treat gastrointestinal haemorrhages. However, a number of adverse cardiovascular effects resulting from an increase in peripheral vascular resistance have been associated with this drug. Terlipressin, however, is more effective, has an improved safety profile and is associated with fewer side effects than vasopressin. Somatostatin, a growth regulatory hormone, achieves haemostasis by decreasing splanchnic blood flow, and is effective in preventing early rebleeding. Somatostatin is effective in treating bleeding oesophageal varices (BOV) and is associated with fewer and more transient side effects than terlipressin. Octreotide, however, has greater stability and a longer half-life than somatostatin, but has a less favourable safety profile. Octreotide displays a number of therapeutic advantages over somatostatin, but not in the treatment of gastrointestinal indications. The development of terlipressin from vasopressin has demonstrated a number of clinical advantages, while the development of octreotide from somatostatin has not shown any significant advantage in the treatment of BOV.

PCPP as a parenteral adjuvant for diverse antigens

The adjuvanticity of the phosphazene polymer, poly[di(carboxylatophenoxy) phosphazene] (PCPP) was examined with a diverse collection of immunogens. PCPP proved to be a potent adjuvant for trivalent influenza virus vaccine, tetanus toxoid, hepatitis B surface antigen, herpes simplex virus glycoprotein gD2 and the capsular polysaccharide, polyribosylribitolphosphate, from Haemophilus influenzae type b. Taken together these results clearly demonstrate the general utility of PCPP as an adjuvant. Furthermore, PCPP was a superior adjuvant at least with TT compared to similar negatively charged polyanions, polymethylacrylic acid and polyacrylic acid.

Poly[di(carboxylatophenoxy)phosphazene] (PCPP) is a potent immunoadjuvant for an influenza vaccine

The adjuvant activity of poly[di(carboxylatophenoxy)phosphazene] (PCPP) on the immunogenicity of formalin-inactivated influenza virions and commercial trivalent influenza vaccine was studied. Regardless of which antigen preparation is used, the addition of 100 micrograms PCPP enhances the HAI antibody response 10-fold over the levels elicited by the vaccine alone. Similarly, PCPP enhanced the IgM, IgG, and IgG1 ELISA antibody titers to influenza antigens at least 10-fold higher than the vaccine alone. In contrast, the IgG2a isotype titers were only enhanced about 2-fold. Immunization of aged mice (22 months old) with trivalent influenza vaccine alone did not sero-convert these mice as measured by HAI or ELISA whereas significant sero-conversion was achieved when mice were immunized with PCPP-formulated trivalent vaccine. The adjuvant activity of PCPP was shown to not be due to a site of injection depot effect. PCPP adjuvanticity was positively correlated to the molecular weight of the polymer.

Randomised trial of octreotide for long term management of cirrhosis after variceal haemorrhage

OBJECTIVE

To assess the efficacy of long term octreotide as adjuvant treatment to programmed endoscopic sclerotherapy after acute variceal haemorrhage in cirrhotic portal hypertension.

DESIGN

Randomised clinical trial.

SETTING

University hospital.

SUBJECTS

32 patients with cirrhotic portal hypertension.

INTERVENTIONS

Programmed injection sclerotherapy with subcutaneous octreotide 50 micrograms twice daily for 6 months, or programmed injection sclerotherapy alone.

MAIN OUTCOME MEASURES

Episodes of recurrent variceal bleeding and survival.

RESULTS

Significantly fewer patients receiving combined octreotide and sclerotherapy had episodes of recurrent variceal bleeding compared with patients given sclerotherapy alone (1/16 v 7/16; P = 0.037, Fisher's exact test), and their survival was significantly improved (P < 0.02, log rank test); this improvement was maintained for 12 months after the end of the study. Combined treatment also resulted in a sustained decrease in portal pressure (median decrease -6.0 mm Hg, interquartile range -10 to -4.75 mm Hg, P = 0.0002) compared with sclerotherapy alone (median increase 1.5 mm Hg, interquartile range 0.25 to 3.25 mm Hg), as well as a significant improvement in liver function as assessed by plasma concentrations of bilirubin, albumin, and alanine aminotransferase and by hepatocyte metabolism of aminopyrine labelled with carbon-14.

CONCLUSION

Long term octreotide may be a valuable adjuvant to endoscopic sclerotherapy for acute variceal haemorrhage in cirrhotic portal hypertension.

A multicentre randomised trial comparing octreotide and injection sclerotherapy in the management and outcome of acute variceal haemorrhage

BACKGROUND

Few studies have compared vasoactive drugs with endoscopic sclerotherapy in the control of acute variceal haemorrhage. Octreotide is widely used for this purpose, but its value remains undetermined.

AIMS

To compare octreotide with endoscopic sclerotherapy for acute variceal haemorrhage.

PATIENTS

Consecutive patients with acute variceal haemorrhage.

METHODS

Patients were randomised at endoscopy to receive either a 48 hour intravenous infusion of 50 pg/h octreotide (n = 73), or emergency sclerotherapy (n = 77).

RESULTS

Overall control of bleeding and mortality was not significantly different between octreotide (85%, 62 patients) and sclerotherapy (82%, 63 patients) over the 48 hour trial period (relative risk of rebleeding 0.83; 95% confidence interval (CI) 0.38 to 1.82), irrespective of Child's grading or active bleeding at endoscopy. One major complication was observed in the sclerotherapy group (aspiration) and two in the octreotide group (pulmonary oedema, severe paralytic ileus). During 60 days of follow up there was an overall trend towards an increased mortality in the octreotide group which was not statistically significant (relative risk of dying at 60 days 1.91, 95% CI 0.97 to 3.78, p = 0.06).

CONCLUSIONS

The results of this study indicate that intravenous octreotide is as effective as injection sclerotherapy in the control of acute variceal bleeding, but further controlled trials are necessary to evaluate the safety of this treatment.

Effects of octreotide on liver regeneration and tumour growth in the regenerating liver

The ability of the liver to regenerate following resection is remarkable. However, there is evidence to suggest that tumour growth within the regenerating liver is significantly increased. As octreotide (a synthetic analogue of somatostatin) inhibits the growth and development of hepatic tumour in rats, we have investigated its effects on liver regeneration, liver blood flow, hepatic reticuloendothelial system activity and tumour growth in the rat following partial hepatectomy (PH). Octreotide significantly inhibited liver regeneration in the rat 1 and 2 weeks following PH when compared with controls (regeneration index: 1.0 and 1.14 cf. 1.14 and 1.4, respectively). There was no significant difference in hepatic arterial or portal venous blood flow following PH in control or octreotide-treated rats. However, portal pressure was significantly reduced in octreotide-treated rats. Hepatic reticuloendothelial system activity was significantly increased in octreotide-treated rats compared with control animals 1 and 2 weeks after hepatectomy (uptake of radiolabelled technetium-99m albumin colloid: 2.2 and 3.9 cf. 1.6 and 1.9). The growth of both HSN (fibrosarcoma) and K12-Tr (colonic adenocarcinoma) cells in the regenerating liver was significantly decreased by octreotide treatment compared with controls (median percentage hepatic replacement: HSN control 71.3%, Octreotide 8.4%, K12-Tr Control 38.3%, Octreotide 4.5%). The results of the present study demonstrate that octreotide inhibits both liver regeneration and tumour growth following PH, possibly via a similar mechanism.

Quantification of voiding dysfunction in patients awaiting transurethral prostatectomy

PURPOSE

We investigated the role of advanced urodynamic analysis in the diagnostic evaluation for transurethral resection of the prostate.

MATERIALS AND METHODS

A total of 62 consecutive patients awaiting transurethral resection of the prostate with the American Urological Association symptom score of more than 12, peak flow rate less than 13 ml. per second and significant residual urine underwent routine video pressureflow studies with advanced urodynamic analysis to quantify outflow function. Postoperative outcome was assessed at 3 months by symptom scores, uroflowmetry and ultrasonography (residual urine).

RESULTS

The parameters used in the diagnostic evaluation for transurethral resection of the prostate did not correlate with urodynamic diagnosis of unequivocal obstruction. Weak detrusor contractility (without significant obstruction) accounted for voiding dysfunction in 50% of the patients. The results of transurethral resection of the prostate were significantly better in patients with unequivocal compared to equivocal obstruction. Furthermore, patients with unequivocal obstruction but weak detrusor contractility had a significantly poorer treatment outcome.

CONCLUSIONS

Advanced urodynamic analysis in the diagnostic evaluation of patients with symptomatic benign prostatic hyperplasia can predict treatment outcome and, therefore, allows the urologist to choose the most appropriate therapeutic option for individuals.

The role of an advanced thermotherapy device in prostatic voiding dysfunction

OBJECTIVES

To investigate the efficacy of an advanced transurethral thermotherapy (TUMT) device (T3, Urologix) using urodynamic analysis in addition to the standard evaluation protocol in patients with symptomatic benign prostatic hyperplasia (BPH).

PATIENTS AND METHODS

Fifty men with symptomatic BPH were assessed using the AUA symptom score, uroflowmetry and ultrasonography (to determine prostatic volume and residual urinary volume) before and 6 weeks, 3, 6 and 12 months after thermotherapy. TUMT was delivered using a focused microwave energy system for 1 h in each patient, treated on an out-patient basis. Video pressure flow studies with advanced urodynamic analysis were also performed before and 3 months after treatment.

RESULTS

The mean AUA symptom score decreased by 63%, the mean peak flow rate increased by 64% and the post-void residual volume decreased by 30% 3 months after treatment; this improvement was maintained at one year after treatment. Advanced urodynamic analysis showed that 52% of the patients had a decreased severity of obstruction. Furthermore, the efficiency of detrusor contraction improved in 86% of the patients. The improvement in the symptom score, flow rate and residual urine was significantly better in patients with marginal obstruction than in patients with unequivocal obstruction.

CONCLUSION

Urodynamic analysis can predict the treatment outcome of TUMT and the results of thermotherapy are significantly better in patients with marginal prostatic bladder outflow obstruction.

Progressive disruption of acinar cell calcium signaling is an early feature of cerulein-induced pancreatitis in mice

BACKGROUND & AIMS

Disruption of pancreatic exocrine secretion is an important feature of acute pancreatitis. Because cytosolic calcium is a key intracellular messenger controlling pancreatic secretion, this study examined patterns of calcium signaling during the early stages of cerulein-induced pancreatitis.

METHODS

Mice were administered hourly intraperitoneal injections of cerulein (50 micrograms/kg), and paired controls were administered saline. Acini were isolated by collagenase from pancreatic tissue harvested after injections 1, 3, 5, and 7 and were loaded with Fura-2. Individual cellular calcium responses to acetylcholine and cholecystokinin were studied using digital imaging.

RESULTS

The proportion of cells maintaining a normal oscillatory calcium response to physiological secretagogue stimulation diminished progressively after increasing cerulein injections. Also, the normal polarized spatial pattern of calcium Increase within individual acinar cells was progressively lost. A sustained response to high-dose stimulation was maintained but with diminishing amplitude. The characteristic calcium response to the Ca(2+)-adenosine triphosphatase inhibitor thapsigargin was maintained, implying that calcium reuptake and extrusion were not impaired.

CONCLUSIONS

Progressive disruption of physiological patterns of pancreatic acinar cell calcium signaling, notably in the secretory pole of the cell, is an early feature of pancreatitis induced by cerulein hyperstimulation. These changes may be important in contributing to the disruption of exocrine secretion in acute pancreatitis.

The effects of Helicobacter pylori colonization on gastric function and the incidence of portal hypertensive gastropathy in patients with cirrhosis of the liver

OBJECTIVES

To investigate the prevalence of Helicobacter pylori infection in 50 cirrhotic patients with biopsy-proven cirrhosis with and without portal hypertensive gastropathy and to study whether or not the effects of H. pylori colonization of the stomach on gastric acid and pepsin secretion, serum gastrin and pepsinogen I levels, gastric mucus, and gastric emptying contributed to the development of portal hypertensive gastropathy in cirrhotics.

METHODS

All patients underwent an upper GI endoscopy followed by determination of basal and pentagastrin and insulin-stimulated gastric acid and pepsin secretion and serum gastrin and pepsinogen I levels. The gastric biopsies were stained to detect H. pylori infection, portal hypertensive gastropathy, and gastritis. The amount of gastric mucus was estimated by a microanalytical technique. The rate of gastric emptying was assessed by the radionuclide method using a semi-solid meal.

RESULTS

Thirty-three (66%) patients had endoscopic evidence of portal hypertensive gastropathy, 10 with the severe (20%) and 23 with mild form (46%). Twenty (40%) patients had histological evidence of H. pylori infection. Eleven out of 33 (33%) patients with endoscopic portal hypertensive gastropathy had microscopic evidence of H. pylori infection. Eighteen out of 20 (90%) patients with chronic active gastritis had concomitant H. pylori colonization. In contrast, the gastric mucosa was histologically normal in 21 of the 30 patients (70%) not infected with H. pylori. Marked hypochlorhydria and reduced pepsin secretion associated with a tendency to hypergastrinemia were observed in cirrhotic patients colonized with H. pylori compared with those without. However, there was no significant difference in serum pepsinogen I concentrations, the ratio of polymeric to degraded gastric mucus, or the rate of gastric emptying between cirrhotics with and without H. pylori colonization of the stomach. Furthermore, these parameters were not significantly different in patients with portal hypertensive gastropathy with and without H. pylori infection.

CONCLUSION

These observations suggest that H. pylori infection is unlikely to be involved in the pathogenesis of portal hypertensive gastropathy.

Increasing hepatic arterial flow to hypovascular hepatic tumours using degradable starch microspheres

The effect of degradable starch microspheres (DSM) on the intrahepatic distribution of a low molecular weight marker, 99Tcm-labelled methylene diphosphonate (MDP), was studied in rats with hypovascular HSN liver tumours. MDP was injected regionally, via the hepatic artery, alone or co-administered with DSM, with or without subsequent occlusion of either the hepatic artery or the portal vein. Tumour vascularity was measured with 57Co-labelled microspheres. Co-injection with DSM immediately significantly increased hepatic retention of marker in both tumour (T) (median 22.40 (range 16.82-39.58)% injected dose) and normal liver (N) (9.08 (4.85-12.59) %ID) the greater effect seen in T (P < 0.01). After DSM degradation, very little MDP remained in N (0.61 (0.28-1.40) %ID) but there was significant retention in T (10.01 (6.73-20.28) %ID, P < 0.01). Clamping the hepatic artery had minimal effect on the retention of MDP when administered alone. Regional injection of 16.5 microM 57Co microspheres resulted in a N:T ratio of 2.25:1. Concomitant injection of the 40 microM DSM was 57Co microspheres reversed this ratio to 1:2. The results indicate that DSM selectively enhances the retention of MDP to a hypovascular hepatic tumour, not by causing intra-tumour stasis, but by directing a greater arterial flow to hypovascular areas in the liver.

Abnormalities of gastric emptying in portal hypertension

OBJECTIVES

To investigate: 1) the rate of gastric emptying of portal hypertensive patients and 2) whether alterations in gastric emptying play any role in the development of portal hypertensive gastropathy.

METHODS

Fifty patients (37 with esophageal varices) with cirrhosis and seven with extrahepatic portal hypertension underwent upper GI endoscopy followed by radionuclide gastric emptying studies using a semi-solid meal. Twenty-six patients also under went corrected wedged hepatic venous pressure measurement. Sixteen normal subjects underwent gastric emptying studies only.

RESULTS

Varices were completely obliterated by sclerotherapy in 17 patients and were patent in 27. Thirty-seven patients had portal hypertensive gastropathy, 25 of whom had mild changes and 12 severe. No significant difference in gastric emptying was observed between patients with mild and severe portal hypertensive gastropathy and between those with portal hypertensive gastropathy and a normal gastric mucosa. There was no significant difference in gastric emptying between normal subjects and portal hypertensive patients although the latter group showed a tendency for faster gastric emptying. No difference in the rate of gastric emptying was observed between portal hypertensive patients with intrahepatic and extrahepatic pathology. However, patients with esophageal varices (patent and obliterated) emptied their stomachs significantly faster than those without (p = 0.01). There was no correlation between the rate of gastric emptying and corrected wedged hepatic venous pressure.

CONCLUSIONS

It would appear that, although alterations in gastric emptying are common in portal hypertension, gastric emptying does not appear to play a causative role in the mucosal changes characteristic of portal hypertensive gastropathy.

Octreotide in the control of post-sclerotherapy bleeding from oesophageal varices, ulcers and oesophagitis

Bleeding from oesophageal varices, oesophageal ulcers or oesophagitis is occasionally massive and difficult to control. Octreotide, a synthetic analogue of somatostin lowers portal pressure and collateral blood flow including that through varices, increases lower oesophageal sphincter pressure, and inhibits the gastric secretion of acid as well as pepsin. Our current experience suggests it is effective in controlling acute variceal haemorrhage. Therefore we have examined the efficacy of octreotide in the control of post-sclerotherapy bleeding from oesophageal varices, oesophageal ulcers and oesophagitis. During the study period 77 patients experienced a significant gastrointestinal bleed (blood pressure < 100 mm Hg, pulse > 100 beats per min or the need to transfuse 2 or more units of blood to restore the hemoglobin level) following injection sclerotherapy of oesophageal varices. The source of bleeding was varices in 42 patients, oesophageal ulcers in 31 and oesophagitis in 4. All patients received a continuous intravenous infusion of octreotide (50 micrograms/h) for between 40-140h. If bleeding was not controlled in the first 12h after commencing octreotide hourly bolus doses (50 micrograms) for 24h were superimposed on the continuous infusion. Haemorrhage was successfully controlled by an infusion of octreotide in 38 of the 42 patients with bleeding from varices, in 30 of 31 patients with oesophageal ulceration, and all patients with oesophagitis. In the 1 patient with persistent bleeding from oesophageal ulceration and in 2 of the 4 with continued haemorrhage from varices, haemostasis was achieved by hourly boluses of 50 micrograms octreotide for 24h in addition to the continuous infusion. No major complications were associated with octreotide administration. The results of this study clearly indicate that octreotide is a safe and effective treatment for the control of severe haemorrhage after technically successful injection of sclerotherapy.

Therapeutic potential of octreotide in the treatment of liver metastases

Octreotide is a synthetic analogue of somatostatin that has clear inhibitory effects on the growth of many animal and human cell lines, including colorectal cell lines both in vitro and in vivo. Colorectal cancer metastatic to the liver is clinically important, both in terms of the number of patients affected and the lack of any effective treatment for the majority of patients. Octreotide inhibits the growth of colorectal liver tumour in a number of experimental models and, in at least three tumour types, inhibits the growth of established micro-metastases. The precise mechanism of action is not known. However, the drug is likely to be most beneficial in the treatment of liver metastases when the tumour burden is relatively small. The available evidence, although experimental, suggests that octreotide may also have a beneficial effect on the development of liver metastases when used as an adjuvant to surgery in colorectal cancer and this area warrants urgent clinical investigation. The cytotoxics which are currently used as an adjuvant to surgery for colorectal cancer have unpleasant side effects which can be life-threatening. There will also be a proportion of patients who have undergone a truly curative resection of their tumour and will thus be treated unnecessarily. The potential benefits of octreotide in the adjuvant setting, although promising, remain speculative, but octreotide has an acceptably low incidence of side effects and can be administered safely for a prolonged period of time.