Endoscopic fluorescent lymphography for gastric cancer

Lymphography by radioisotope or dye is a well-known technique for visualizing the lymphatic drainage pattern in a neoplastic lesion and it is in use in gastric cancer. Indocyanine green (ICG) more recently has been validated in fluorescent lymphography studies and is under evaluation as a novel tracer agent in gastric cancer. The amount and dilution of ICG injected as well as the site and the time of the injection are not standardized. In our unit, endoscopic submucosal injections of ICG are made as 0.5 mg in 0.5 mL at four peritumoral sites the day before surgery (for a total of 2.0 mg in 2.0 mL). Detection instruments for ICG fluorescence are evolving. Near-infrared systems integrated into laparoscopic or robotic instruments (near-infrared fluorescence imaging) have shown the most promising results. ICG fluorescence recognizes the node that receives lymphatic flow directly from a primary tumor. This is defined as the sentinel lymph node, and it has a high predictive negative value at the cT1 stage, able to reduce the extent of gastrectomy and lymph node dissection. ICG also enhances the number of lymph nodes detected during extended lymphadenectomy for advanced gastric cancer. Nevertheless, the practical effects of ICG use in a single patient are not yet clear. Standardization of the technique and further studies are needed before fluorescent lymphography can be used extensively worldwide. Until then, current guidelines recommend an extensive lymphadenectomy as the standard approach for gastric cancer with suspected metastasis.

Issues of internal medicine in psychiatric patients

In opposition to opinions of a sectorialization of psychiatric illness, phenomena of comorbidity due to susceptibility of psychiatric patients to contract other diseases--whose co-presence is difficult to translate and treat--are more and more evident. In this review we have marked main issues of internal medicine in psychiatric patients. This review will discuss particularly main cardiovascular diseases (CAD, VTE), lung diseases (COPD,asthma, restrictive lung disease) gastroenterologic disease (IBS, coeliac disease, ulcerous rectocolitis), diabetes and metabolic syndrome, more likely infections verified in these patients (HIV, viral hepatitis), cancers considerably underlined (breast cancer, colon-rectal cancer and lung cancer), internistic issues in alcohol abuse which is a frequent state in these subjects. A special chapter is dedicated to antipsychotics. These drugs are characterized by a complex action modality and by frequent interactions with a large number of other drugs.

Male sexual disturbances in liver diseases: what do we know?

The alterations of sexual function known as the erectile dysfunction are quite frequent among patients affected by liver diseases and they tend to increase in advanced liver failure. This process is directly linked to cirrhosis or its treatments, such as liver transplantation, or to certain drugs (e.g. beta-blockers). Independent of cirrhosis, other factors may cause sexual problems in these patients. Alcohol itself seems to worsen sexual function in the absence of cirrhosis. Viral hepatitis has an uncertain influence on male gonadic function and even antiviral therapy itself can worsen some seminal and hormonal parameters, although it is reversible. Quality of life may be greatly decreased in cases of cirrhosis where these alterations are present, so it is important to value and care for them, if possible. This review investigates the major male sexual disturbances in liver diseases of various origins.

Type 1 autoimmune hepatitis and adipokines: new markers for activity and disease progression?

PURPOSE

Cytokines may play an important role as inflammatory factors in liver diseases. There is some evidence suggesting a link between adiponectin-biliary function and liver disease. The aim of this study was to clarify the behavior of adipokines in autoimmune hepatitis type 1.

METHODS

We assessed the circulating levels of adiponectin, tumor necrosis factor-alpha, resistin and leptin in 42 patients with autoimmune hepatitis, comparing them with 42 healthy subjects who were matched for age and sex and with 31 patients with nonalcoholic steatohepatitis (NASH), evaluating the associations with markers of cytolysis, cholestasis, and histological severity.

RESULTS

Adiponectin and TNF-alpha values were higher in patients compared to controls. The patients showed significantly higher Homeostasis Model Assessment values, suggesting an increased insulin resistance and serum levels of adiponectin positively correlated with gamma-glutamyltranspeptidase and alkaline phosphatase values after a simple regression analysis. Serum levels of resistin positively correlated with elevated aminotransferases and bilirubin values, and serum levels of TNF-alpha positively correlated with elevated alanine-aminotransferase and resistin values. The concentration of adiponectin increased significantly with staging of the disease. Patients with NASH showed lower levels of adiponectin and higher levels of resistin than AIH patients and controls.

CONCLUSIONS

Patients with AIH showed significantly higher adiponectin concentrations than controls despite their higher HOMA-IR values. The significant correlation between adiponectin levels and serological features of cholestasis suggested an association with biliary function. Our results indicate that adiponectin may be a possible marker for disease progression in AIH.

Characteristics of liver diseases in the elderly: a review

Chronic liver diseases are becoming more commonly diagnosed in the elderly, although they are not age-related. Most liver functions in advanced age appear to be well preserved, but some changes in liver morphology and physiology with aging may lead to several differences in clinical course and management of liver diseases in older patients compared to younger. A cautious individual evaluation is therefore required in aged patients, especially concerning reduced hepatic drug clearance and comorbidity. Many chronic liver diseases are characterized by a slow and indolent course with non-specific clinical presentation and this may lead a later diagnosis in the elderly. The presence of an advanced liver disease or cirrhosis is more frequent in old patients as the first clinical presentation. No significant differences in diagnostic investigations or treatment options occur between the elderly and the young. Hepatocellular carcinoma is an affliction of the old patients (mean age 65 age) and follow up with ultrasonography and alpha-fetoprotein is mandatory. Advanced age is not considered a contraindication to liver transplantation, but recipients older than 60 years with poor hepatic synthetic function and comorbidity show a worse prognosis with lower survival rates. This review focuses on new emerging conditions, clinical features and updated therapeutic approaches of the most common chronic liver diseases among the elderly.

Plasma adiponectin levels in primary biliary cirrhosis: a novel perspective for link between hypercholesterolemia and protection against atherosclerosis

INTRODUCTION

Hypercholesterolemia is a common finding in primary biliary cirrhosis (PBC), but the risk of cardiovascular events in PBC patients is not increased in respect to the general population. High serum adiponectin levels appear to play a protective role in the development of either metabolic syndrome or cardiovascular disease.

AIM

To investigate factors potentially preventing atherosclerosis in PBC patients.

METHODS

Circulating levels of adiponectin, resistin, leptin, and tumor necrosis factor-alpha (TNF-alpha) were measured in 137 consecutive PBC patients (125 women, 12 men; mean age 61.6 +/- 12.3 yr), 137 sex- and age-matched healthy controls, and 30 female patients with nonalcoholic steatohepatitis (NASH) and associated metabolic syndrome.

RESULTS

The body mass index (BMI) was comparable in the three groups, whereas total cholesterol was significantly higher in both PBC and NASH cases than in controls (221.6 +/- 50.5 mg/dL in PBC vs 221.7 +/- 39.7 mg/dL in NASH vs 209.8 +/- 39.2 mg/dL in controls, P < 0.05). Serum concentrations of adiponectin, resistin, and leptin were significantly higher in PBC patients than in either NASH cases or controls (P < 0.05). Among the PBC patients, only adiponectin correlated positively with histological progression of the disease (P= 0.001) and negatively with BMI (P= 0.01). Logistic regression analysis revealed that adiponectin correlated independently with age, BMI, Mayo score, and gamma-glutamyl transpeptidase.

CONCLUSIONS

The high adiponectin concentrations observed in PBC patients should be regarded as a possible protective factor against atherogenesis. The search for further protective factors should be encouraged.

Nitrosative stress predicts the presence and severity of nonalcoholic fatty liver at different stages of the development of insulin resistance and metabolic syndrome: possible role of vitamin A intake

BACKGROUND

Although nonalcoholic fatty liver disease (NAFLD) is associated with the metabolic syndrome, the mechanisms responsible for the development of NAFLD at different stages of the development of insulin resistance are unknown. Diet, adipokines, and nitrosative stress have been linked to both NAFLD and insulin resistance.

OBJECTIVE

We aimed to identify the factors that are specifically associated with NAFLD at different stages in the development of insulin resistance and the metabolic syndrome.

DESIGN

Circulating concentrations of adipokines (ie, tumor necrosis factor-alpha, adiponectin, resistin, leptin, and interleukin-6), markers of nitrosative stress (nitrotyrosine), dietary habits, and MTP -493G/T polymorphism were cross-sectionally related to the presence and severity of insulin resistance (homeostasis model assessment index for insulin resistance: >or=2), the metabolic syndrome, and fatty liver in 64 nonobese nondiabetic patients with NAFLD (33 insulin-sensitive and 31 insulin-resistant subjects) and 74 control subjects without liver disease who were matched for sex, BMI, homeostasis model assessment index for insulin resistance status, and the various features of the metabolic syndrome.

RESULTS

Persons with NAFLD had greater systemic nitrosative stress and a lower intake of vitamins A and E than did control subjects, but the 2 groups did not differ significantly in any other features. Nitrotyrosine and adiponectin concentrations and vitamin A intakes independently predicted alanine aminotransferase concentrations in NAFLD patients and liver histology in a subgroup of 29 subjects with biopsy-proven nonalcoholic steatohepatitis.

CONCLUSIONS

Oxidative stress is operating in NAFLD and nonalcoholic steatohepatitis, even in the absence of insulin resistance, the metabolic syndrome, and hypoadiponectinemia, which aggravate liver histology at more severe stages of metabolic disease. The possible pathogenetic role of reduced vitamin A intake in NAFLD warrants further investigation.

Gastrointestinal problems in the elderly

Gastrointestinal (GI) disorders represent the third cause of consultations by general practitioners among subjects older than 65 years in Western countries. Although GI diseases in the elderly do not show peculiar characteristics, they often may present a more severe course, due to comorbidities and intake of many drugs. Moreover, several illnesses, such as neoplasias, are more frequent in the elderly. This review focuses on the epidemiological, physiopathological, and clinical aspects of GI diseases in advanced age. Some relevant issues are considered. It is advisable to avoid empirical approaches in the elderly and to choose endoscopic examinations because of the possibility to detect conditions such as already complicated gastroesophageal reflux disease or peptic ulcers as well as to diagnose precociously neoplastic formations in esophagus, stomach or colon. The monitoring of chronic liver disease is very important, mainly to prevent or detect hepatocellular carcinoma early. Idiopathic (or autoimmune) chronic pancreatitis in the elderly is more frequent than other forms of pancreatic diseases, like alcoholic pancreatitis.

Diagnostic and therapeutic questions in overlap syndromes of autoimmune hepatitis

The term ''overlap syndromes of liver diseases'' includes coexistence of autoimmune hepatitis (AIH), primary sclerosing cholangitis (PSC), primary biliary cirrhosis (PBC). Due to their unknown etiology, as well as their variable presentation with mixed clinical and biochemical features, these overlap syndromes are often a diagnostic and therapeutic challenge for hepatologists. The most frequent association reported occurs between AIH and PBC. More rare is the overlap between AIH and PSC, typical in young age and often concomitant with an inflammatory bowel disease as ulcerative colitis. The treatment of choice is based on ursodeoxycholic acid and immunosoppressive drugs, used at the same time or consecutively, according to the course of disease. Histological examination seems an important tool, but often does not help for a correct diagnosis due to lack of specificity. Two particular forms of variant syndrome are the so called outlier syndromes, without clear characteristics of overlap: the autoimmune cholangitis, probably a form of PBC anti-mitochondrial antibodies negative, and the hepatitis C virus related with stigmata of autoimmunity, such as nonspecific autoantibodies at low titer. The diagnostic score system elaborated in 1999 by the International AIH Group can help for diagnosis, even if its definite validity is lacking.

Type I autoimmune hepatitis: clinical course and outcome in an Italian multicentre study

BACKGROUND

Many reports of autoimmune hepatitis (AIH) were written in the 'pre-Hepatitis C era' and data on the natural history are still incomplete.

AIM

To evaluate the clinical presentation and the natural history of type I AIH.

METHODS

Seventy-three consecutive patients with a regular follow-up of at least 2 years were prospectively included in the study. The mean follow-up was 91 +/- 61 months.

RESULTS

Patients with 'acute' onset at presentation were significantly older than patients with 'chronic' onset (P < 0.05) and had significantly higher serum levels of transaminase, gamma-glutamyltransferase and bilirubin; Prothrombin time was significantly lower in the said group compared with AIH patients with 'chronic' onset. In 4 of 63 (6.3%) female patients, AIH had the onset during pregnancy; in all of them the outcome of pregnancy was favourable. The major events during the follow-up included oesophageal varices (n = 9) and ascites (n = 4), and 60 patients remained in remission while receiving immunosuppression. None of the patients died during the follow-up, but seven patients were transplanted. The cumulative transplant-free probability of survival was 73.5% at 280 months.

CONCLUSIONS

Elderly patients have more frequently an acute onset at presentation. Survival in AIH is apparently good; with early diagnosis, and improved medical therapy, liver transplantation for AIH will become a rare event in future.

Alterations of seminal and hormonal parameters: An extrahepatic manifestation of HCV infection?

AIM: To evaluate the possible influences of HCV infection and relative antiviral treatment on seminal parameters and reproductive hormonal serum levels.

METHODS: Ten male patients with HCV-related chronic hepatitis and 16 healthy male volunteers were studied. In all subjects seminal parameters (nemaspermic concentration, progressive motility, morphology) and hormonal levels were determined. Seminal parameters and inhibin B, follicle-stimulating hormone, luteinizing hormone, total and free testosterone, estradiol, prolactine in patients were measured after six and twelve months of antiviral combined (interferon + ribavirin) treatment.

RESULTS: Patients before treatment showed a significantly lower nemaspermic motility and morphology as well as lower inhibin B and free testosterone levels than controls. Inhibin B levels in cases were improved six and 12 mo after treatment in five responders (161.9 ± 52.8 pg/mL versus 101.7 ± 47.0 pg/mL and 143.4 ± 46.1 pg/mL versus 95.4 ± 55.6 pg/mL, respectively). Hormonal pattern of patients did not significantly change after treatment, with the exception of estradiol levels with an initial reduction and an overall subsequent increment (19.7 ± 6.4 pg/mL versus 13.6 ± 5.0 pg/mL versus 17.3 ± 5.7 pg/mL). However in 1-year responders a significant increment of free testosterone (14.2 ± 2.54 pg/mL versus 17.1 ± 2.58 pg/mL) occurred. An impairment of nemaspermic morphology occurred, while other seminal parameters did not change significantly during antiviral treatment.

CONCLUSION: Patients with HCV infection show worse spermatic parameters than controls, suggesting a possible negative influence of virus on spermatogenesis, with further mild impairment during antiviral treatment. However therapy could improve the spermatic function, as suggested by the increased inhibin B levels and improved hormonal pattern in responders. Further studies are needed to confirm these preliminary intriguing results.

Adipokines in NASH: postprandial lipid metabolism as a link between adiponectin and liver disease

Circulating levels of four adipokines (adiponectin, TNF-alpha, leptin, and resistin) and the postprandial lipid and adiponectin responses to an oral fat load were assessed in 25 non-obese, non-diabetic patients with biopsy-proven nonalcoholic steatohepatitis (NASH) and correlated with metabolic indices and liver histology. Circulating adiponectin was lower in NASH compared with controls (5,476 +/- 344 vs. 11,548 +/- 836 ng/mL; P = .00001) and on multiple regression analysis correlated negatively with liver steatosis, necroinflammation (OR = 5.0; P = .009), and fibrosis (OR = 8.0; P = .003). The magnitude of postprandial lipemia was significantly higher in NASH than in controls and was related to fasting adiponectin (beta = -0.78; P = .00003). Controls showed a significant increase in serum adiponectin in response to the fat load, whereas patients with NASH showed a slight decrease. Postprandial free fatty acids response correlated inversely with adiponectin response in both groups and independently predicted the severity of liver steatosis in NASH (beta = 0.51; P = .031). In conclusion, hypoadiponectinemia is present before overt diabetes and obesity appear and correlates with the severity of liver histology in NASH. Impaired postprandial lipid metabolism may be an additional mechanism linking hypoadiponectinemia and NASH and posing a higher cardiovascular risk to these subjects. The mechanism(s) underlying these differences are unknown, but the type of dietary fat seems to play a role. These findings may have important pathogenetic and therapeutic implications in both liver and metabolic disease.

Viral load at the time of liver transplantation and risk of hepatitis B virus recurrence

Hepatitis B virus (HBV) recurrence after liver transplantation is significantly reduced by prophylaxis with hepatitis B immune globulins (HBIG) or antiviral drugs in nonreplicating patients and by the combination of both drugs in replicating patients. However, the load of HBV DNA, which defines replicating status in patients undergoing liver transplantation, remains unclear. This study analyzes the correlation between the viral load, tested with a single amplified assay, at the time of liver transplantation, and the risk of hepatitis B recurrence in 177 HBV carriers who underwent transplantation in a single center from 1990 to 2002. Overall, HBV relapsed after surgery in 15 patients (8.5%) with a 5- and 8-year actuarial rate of recurrence of 8% and 21%, respectively. After liver transplantation hepatitis B recurred in 9% of 98 selected subjects treated only with immune globulins and in 8% of 79 viremic patients who received immune globulins and lamivudine (P = NS). A linear correlation was observed between recurrence and viral load at the time of surgery. In transplant patients with HBV DNA higher than 100,000 copies/mL, 200-99,999 copies/mL, and DNA undetectable by amplified assay, hepatitis B recurred in 50%, 7.5%, and 0% of patients, respectively. Overall, a viral load higher than 100,000 copies/mL at the time of liver transplantation was significantly associated with hepatitis B recurrence (P = .0003). In conclusion, spontaneous or antiviral-induced HBV DNA viral load at the time of surgery classifies the risk of HBV recurrence after liver transplantation and indicates the best prophylaxis strategy.

Lack of association between seroprevalence of Helicobacter pylori infection and primary biliary cirrhosis

AIM: To determine the association between seroprevalence of Helicobacter pylori (H pylori) infection and primary biliary cirrhosis (PBC).

METHODS: In this case-control study, 149 consecutive patients (10 males, 139 females, mean age 58.2 ± 11 years, range 26-82 years) suffering from PBC and 619 consecutive healthy volunteer blood donors (523 males, 96 females, mean age 47 ± 5.3 years, range 18-65 years) attending the Hospital Blood Bank and residing in the same area were recruited. A commercial enzyme linked immunosorbent assay was used to detect anti-H pylori (IgG) antibodies in serum.

RESULTS: Antibodies to H pylori were present in 78 (52.3%) out of 149 PBC-patients and in 291 (47%) out of 619 volunteers (P = 0.24, OR 1.24, 95% CI: 0.85-1.80). In the subjects less than 60 years old, the prevalence of H pylori infection among PBC-patients (40/79) was slightly higher than in controls (50.6% vs 46.2%) P = 0.46, OR = 1.19, 95% CI: 0.72-1.95). In those over 60 years, the prevalence of H pylori infection was similar between PBC-patients and controls (54.2% vs 57.8%, P = 0.7, OR 0.86, 95% CI: 0.36-2.07).

CONCLUSION: There is no association between seroprevalence of H pylori infection and primary biliary cirrhosis.

[Autoimmune hepatitis: present knowledge]

Autoimmune hepatitis (AIH) is a rare and chronic disease which may lead to liver cirrhosis if not correctly treated. Its etiology is unknown, but some progresses have been obtained in the knowledge of damage pathogenesis, its immune mechanisms and genetic predisposition (female gender, presence of HLA DR3 and HLA DR4). It seems that such predisposition favours some agents (e.g. drugs or viruses) to trigger the pathological process. Patients present with variable, often few and unspecific symptoms. Diagnosis is made on the basis of anamnestic (absence of other causes, such as virus infections or alcohol abuse), serological (autoantibodies, high levels of aminotransferases, hypergammaglobulinemia), and histological data (piecemeal necrosis further to bridging necrosis, panlobular and multilobular necrosis); these data are processed by a scoring system which is helpful for the diagnostic definition. Therapy is founded in immunosuppressor drugs, mainly steroids and azathioprine, but a lot of other drugs have been studies for cases of recurrence and of intolerance to the standard treatment.

Overlap syndromes of autoimmune hepatitis: what is known so far

The pattern of some autoimmune hepatitis can be difficult to classify, sometimes due to the overlap of these with primary biliary cirrhosis, primary sclerosing cholangitis and chronic viral hepatitis. The etiology of these variant forms remains unclear. The distinction among the overlap syndromes poses different problems both of prognosis and therapeutic approach. Presently, the utility of the scoring system devised and revised by the International Autoimmune Hepatitis Group regarding these cases is under discussion. Histological examination seems to be an important tool, but often the result does not help in defining a correct diagnosis. To date, the overlap syndromes can be classified at an intermediate level between cholestatic forms of autoimmune hepatitis or hepatic forms of cholestatic syndromes, but it cannot be excluded that the syndromes represent independent disorders.

The esophageal chest pain. An update for clinicians

Chest pain is a common symptom and even when there is evidence of only minor obstructive coronary artery disease on angiography, it leads to disability and imposes a substantial economic burden on health care system. Gastroesophageal reflux disease (GERD) and esophageal dysmotility disorders are thought to play an important role in the genesis of non-cardiac chest pain. Its pathogenetic mechanism remains unclear. The esophageal origin of the symptom may be identified by an aggressive trial of high-dose antisecretory drugs or an abnormal prolonged ambulatory pH monitoring study. Endoscopy is often normal and less useful in this population than in those with heartburn as presenting symptom. The use of manometry, with provocative testing to evaluate for esophageal motility abnormalities or esophageal sensitivity, allows optimal evaluation of those who do not have GERD. Patients with non-cardiac chest pain of unknown origin should be carefully screened for the occurrence of esophageal disorders but further research is needed to clarify the role of the latter on the pathogenesis of this symptom.

Helicobacter pylori seroprevalence in patients with autoimmune hepatitis

Autoimmune hepatitis is characterized by a continuing hepatocyte necrosis that usually progresses to liver cirrhosis. Autoimmunity is also a feature of chronic infection by Helicobacter pylori, a gram-negative bacterium involved in the pathogenesis of peptic ulcer and upper gastrointestinal bleeding, with both events frequently occurring in patients with chronic liver disease. A newly described pathogenetic mechanism for chronic hepatitis and hepatocellular carcinoma in the mouse is linked to Helicobacter spp. infection. A high prevalence of H. pylori infection was demonstrated in patients with viral-related cirrhosis but never studied in cases of autoimmune hepatitis. In a case-control study, we examined 31 consecutive patients (25 women and 6 men, age range 20-66, mean age 46 +/- 4.3 years) suffering from autoimmune hepatitis and 62 sex- and age-matched blood donors (50 women, 12 men, age range 20-65, mean age 46 +/- 5.4 years) resident in the same area. Antibodies to H. pylori were present in 20 of 31 (64.5%) autoimmune patients compared to 33 of 62 (53.2%) controls (P = 0.3, odds ratio 1.60, 95% CI 0.60-4.28). The difference was not statistically significant either in female or male patients. In conclusion, the prevalence of H. pylori infection in patients and controls was similar in our study of patients with chronic autoimmune hepatitis.

[Variant syndromes in autoimmune hepatic diseases]

Some autoimmune hepatic diseases patterns can be of difficult classification, sometimes as overlap of autoimmune hepatitis, primary biliary cirrhosis, primary sclerosing cholangitis and chronic viral hepatitis. The recognition of these forms is not so easy, but it is necessary for an effective therapeutic approach. At present, the specificity in these cases of the score system done and revised by the International Autoimmune Hepatitis Group is being discussed. Patients showing such diseases have different modalities of presentation of their hepatic disease and different courses. The role of histology appears to be important, but often the overlap of more manifestations is not helpful to a correct diagnostic definition. The variant syndromes could be classified as intermediate patterns of cholestatic forms and of autoimmune hepatic diseases or cholestatic forms of autoimmune hepatitis or hepatitic forms of cholestatic syndromes.

Genetic variation in Fitzroya cupressoides (alerce), a threatened South American conifer

Fitzroya cupressoides (alerce, Cupressaceae) is a large and exceptionally long-lived conifer, endemic to a restricted area of southern Chile and neighbouring areas of Argentina. As a result of its high economic value, the species has been severely exploited for timber, and remnant populations are fragmented and often highly disturbed. The species is thought to have undergone a major range contraction during the last glaciation. In order to assess the extent of genetic variation using DNA markers within and between populations of this species, samples were obtained from throughout the natural range and analysed for random amplified polymorphic DNA (RAPD) variation. Eight 10-mer and three 15-mer primers were used to produce a total of 54 polymorphic bands. Shannon's diversity estimates were calculated to provide an estimate of the degree of variation within each population. Values varied from 0.343 to 0.636 with only the lowest value differing significantly from the others (Spop = 0.547). This indicated that there is a significant degree of variation within each population, and did not provide evidence for genetic 'bottle-neck' effects within the species. A pairwise distance measure calculated from the RAPD data was used as an input for principal coordinate (PCO) and AMOVA analyses. The first three principal coordinates of RAPD distances described 8.3, 5.9 and 5.4% of the total variance, respectively, and a degree of clustering of samples according to their geographical origin was detectable. AMOVA analysis indicated that although most of the variation (85.6%) was found within populations, a significant proportion (P < 0.002) was attributable to differences between populations. An UPGMA dendrogram constructed using phi ST values derived from AMOVA produced a pattern broadly similar to that produced by the PCO, highlighting differences between three main groups of populations within Chile: those from the northern Coastal Range, the southern Coastal Range and Central Depression, and the Andes. Populations from Argentina also emerged as significantly different from those in Chile. These results are interpreted in the context of the postglacial history of the species, and their implications for the development of conservation strategies for Fitzroya are discussed.

Minimax refining of wideband antireflection coatings for wide angular incidence

The design of antireflection coatings at any light incidence is a challenging task in optics. To this aim, a minimax method is presented: it minimizes the maximum deviation of the spectral reflectance from the desired specifications over the wavelength for a given set of incidence angles. Refining is limited to lossless coatings with assigned refractive indices and undetermined thicknesses; the algorithm consists of iterating appropriate linear optimization steps. In the examples some minimax-refined coatings are compared with coatings reported in the literature.

Continuation method for synthesizing antireflection coatings

A continuation method for synthesizing antireflection multilayer coatings is presented. It takes into account the family of similar problems constituted by the syntheses of spectrally flat coatings that approximate different transmittance levels in the range 0-1. This method traces a path moving from the transmittance (in air) of the chosen substrate to the full transmittance. Whenever one or more thicknesses become too thin, this path is branched by investigating the existence of other local minima, so several optimal designs characterized by different numbers of layers are obtained. Some examples show the capabilities of the proposed synthesis.

Minimax refining of optical multilayer systems

A new minimax method for refining optical multilayer systems is presented. It minimizes the maximum deviation of the spectral transmittance from the desired specifications. These are assigned in such a general way that any shape can be approximated. The algorithm consists of iterating optimization steps that are obtained by developing the transmittance in the Taylor expansion versus the known parameters and solved by piecewise-linear programming. The investigation is limited to the design of losslessmultilayers with assigned refractive indices and undetermined thicknesses. Some minimax-refined designs are compared favorably with those reported in the literature.

Optical glass filters: an algorithm for optimum design

A method based on an optimization algorithm is presented for designing optical glass filters arranged in series. It implies specially structured applications of linear programming, which automatically reject too thin glasses. The algorithm enables work on an original very large set of glasses to be achieved in acceptable CPU time.