Eating behavior and adherence to dietary prescriptions in obese adult subjects treated with 5-hydroxytryptophan

Previous observations have shown that oral administration of 5-hydroxytryptophan (5-HTP) without dietary prescriptions causes anorexia, decreased food intake, and weight loss in obese subjects. To confirm these data over a longer period of observation and to verify whether adherence to dietary restriction could be improved by 5-HTP, 20 obese patients were randomly assigned to receive either 5-HTP (900 mg/d) or a placebo. The study was double-blinded and was for two consecutive 6-wk periods. No diet was prescribed during the first period, a 5040-kJ/d diet was recommended for the second. Significant weight loss was observed in 5-HTP-treated patients during both periods. A reduction in carbohydrate intake and a consistent presence of early satiety were also found. These findings together with the good tolerance observed suggest that 5-HTP may be safely used to treat obesity.

Abnormal substrate metabolism and nutritional strategies in cancer management

Impairment of the nutritional state plays a major role in the morbidity and mortality of cancer patients. However, the opportunity of providing artificial nutritional support to these patients is still debated, because of the concern that energy substrates administered to replete the host may concomitantly stimulate tumor growth. A correct nutritional approach to cancer patients should thus be based on a thorough knowledge of both host and tumor metabolic needs and host-tumor metabolic interactions. Specific modifications of plasma levels of glucogenic, aromatic, sulfur-containing and branched-chain amino acids have been demonstrated in cancer patients, indicating a specific influence of the tumor on amino acid metabolism. Little is known about protein metabolism in neoplastic tissue. Interference with tumor growth has been attempted by deprivation of single amino acids with controversial results. Increased gluconeogenesis and insulin resistance are responsible for the two main abnormalities in carbohydrate metabolism in cancer patients, namely increased glucose turnover and impaired glucose tissue disposal. Lipid metabolism is also affected by the neoplasm: soluble factors such as "lipid-mobilizing factor" lead to increased fat mobilization from adipose tissue; plasma elimination of exogenous triglycerides has also been found to be reduced probably because of a tumor-related decrease in lipoprotein lipase activity. The differences in glucose and fat utilization between tumor and host should be considered in the nutritional approach to cancer patients. Data in this respect are controversial and have been obtained only in experimental animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Two bacteriophage T4 base plate genes (25 and 26) and the DNA repair gene uvsY belong to spatially and temporally overlapping transcription units

The bacteriophage T4 DNA recombination-repair gene uvsY located at or near an origin of DNA replication and adjacent to the late base plate genes 25 and 26. Our present results reveal a complex transcription pattern in the region encompassing these genes. Most significantly, uvsY and two ORFs, downstream of it, all of which are transcribed from a middle promoter before the onset of DNA replication, are also part of a larger late transcription unit which includes the base plate genes 25 and 26. The late genes 25 and 26 are transcribed not only late, but also early from one or several early promoters further upstream. Translation, however, is inhibited by secondary structures which sequester the ribosome binding site in the early transcript. We discuss possible advantages of these transcriptional patterns for T4 DNA recombination, replication, and repair. The predicted and in vivo-expressed 23.9-kDa product of gene 26 is smaller than the reported size of gene 26 protein isolated from base plates, suggesting that nascent gp26 might be processed to a larger protein during assembly.

Effect of energy substrate manipulation on tumour cell proliferation in parenterally fed cancer patients

The effects of isocaloric carbohydrate-based vs. fat-based total parenteral nutrition (TPN) regimens on cancer cell proliferation and host nutritional status were evaluated in 27 patients with tumours of the gastro intestinal tract consecutively assigned to receive for 14 days: a glucose-based (A) or a lipid-based (B) TPN formula, or an oral diet (C) isocaloric and isonitrogenous to A and B. Cancer cell replication rate was evaluated by thymidine labelling index (LI) on tumour samples before and at the end of each nutritional regimen. The number of replicating cells increased by 32.2% in patients receiving regimen A. LI decreased by 24.3% in patients given regimen B. LI values were slightly increased (+15%) in patients maintained on regimen C. Nutritional status remained within normal limits. None of the LI changes observed between and within the three arms of the trial were found to be statistically significant. Thus we failed to prove that glucose consistently stimulates or lipids inhibit tumour proliferation despite a trend in this sense.

Cell kinetics of gastrointestinal tumors after different nutritional regimens. A preliminary report

Forty-four cases of different untreated gastrointestinal tumors were studied with regard to cell kinetic activity. As a pilot experiment, we also determined the 3H-TdR Labeling Index (LI) in 28 patients in basal conditions and after 15 days of nutritional manipulation with prevalently lipid-based or glucose-based feeding to ascertain whether selective nutritional regimens could affect tumor proliferation. Preliminary results from this study indicate that a kinetic perturbation is induced in tumor cells by nutritional manipulation. Lipid-based feeding seems to produce effects similar to those of chemical or physical anticancer agents, thus suggesting a possible supporting role of nutritional manipulation in cancer treatment strategy.

Increased plasma free tryptophan levels in human cancer: a tumor related effect?

High free tryptophan (F-TRP) plasma levels are found in cancer patients (CP). F-TRP plasma concentrations are affected by the levels of its carrier, albumin (ALB), and free fatty acids (FFA) competing with TRP for ALB binding sites. The lack of correlation between F-TRP, ALB and FFA in CP suggests a tumor-dependent effect on the rise in F-TRP. To verify this hypothesis, F-TRP, ALB and FFA levels were assayed in 12 lung and 16 breast CP susceptible to radical surgery, before and 15 days after surgical removal of the tumor. F-TRP levels significantly decreased after tumor ablation. Since no correlation was found between F-TRP, ALB and FFA variations, it is conceivable that the tumor itself may be responsible for the high F-TRP levels in CP.

Plasma and CSF tryptophan in cancer anorexia

Eighteen untreated cancer patients and ten sex- and age-matched healthy volunteers were studied. In all patients eating behavior was investigated by means of a specific questionnaire from which the presence of anorexia and anorexia-related symptoms was assessed. To investigate the role of tryptophan in cancer anorexia, fasting plasma and CSF levels of tryptophan and other neutral amino acids were assayed in patients and controls. Cancer patients showed abnormally high plasma free tryptophan levels. In case of patients with cancer anorexia a significant rise of the ratio in plasma between free and tryptophan/large neutral amino acids, competing with tryptophan for its brain entry, was observed. This increase was correlated to a consistent rise of CSF tryptophan levels suggesting a specific role of the serotoninergic system in the pathogenesis of cancer anorexia.

Plasma clearance of exogenous lipids in patients with malignant disease

Abnormalities in lipid metabolism have been widely described in cancer-bearing patients and animals. In particular, the presence of the tumor seems to profoundly affect triglyceride (TG) utilization by interfering with lipoprotein lipase (LPL) activity. Exogenous TG plasma clearance was evaluated in 10 nonmalnourished patients with cancers of various origin and 10 normolipidemic volunteers by means of a three-stage intravenous lipid clearance test. This technique allows precise determination of both the fractional removal rate (K2) and the maximal clearing capacity (K1) for exogenous lipids. Mean K2 values (min-1) were found to be significantly reduced in cancer patients compared with control subjects (0.07 +/- 0.006 vs 0.13 +/- 0.013 SEM, p less than 0.005). K1 values (mumol/L/min) were also found to be significantly lower in cancer patients than in the control group (109.43 +/- 6.3 vs 143 +/- 6.3 SEM, p less than 0.01). The data obtained indicate that the capacity to eliminate exogenous lipids from the bloodstream is reduced in cancer-bearing patients. This may be the consequence of a tumor-related impairment of LPL system activity.

[Metabolico-nutritional changes in the cancer patient]

The severe impairment of the nutritional state, which usually accompanies malignant diseases, heavily contributes to the high morbidity and mortality rates observed in cancer patients. Nevertheless, the utility of an artificial energy supply to these patients is still controversial because the nutrients given to replete the host may also stimulate tumor growth. Consequently, a correct nutritional approach for cancer patients should be based upon a well-defined understanding of tumor as well as host-metabolic needs. In this regard, the most typical metabolic abnormalities observed in cancer patients and experimental animals are examined. Specific modifications of the plasma levels of different groups of amino acids--including glucogenic, aromatic, sulphur-containing and branched-chain amino acids--have been observed in cancer patients independently of the their degree of malnutrition, glucose tolerance and tumor diffusion. This may reflect a series of specific modifications induced by the neoplastic tissue on host's protein turnover. Little information is available regarding the protein metabolism in the neoplastic tissue. A number of attempts have been made to reduce tumor growth by withholding single amino acids considered essential to the tumor; nevertheless, the results obtained are still controversial. The two major abnormalities of carbohydrate metabolism observed in cancer patients are an increased glucose turnover and an impaired glucose tissue disposal. The former seems to be due to an increased glucogenesis, whereas the latter may be attributed to an insulin resistance in contrast to the high anaerobic glucose utilization observed in the neoplastic tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacteriophage T4 late gene expression: overlapping promoters direct divergent transcription of the base plate gene cluster

Eight 5' ends of RNA molecules which encompass the bacteriophage T4 base plate late genes 51 to 26 region have been mapped by S1 nuclease protection and reverse transcription within a 246-bp DNA segment. Two of eight 5' ends are initiated at two absolutely conserved late promoter sites, P51 and P26a, that direct RNA synthesis on opposite strands. These two promoters share four of eight promoter sequence base pairs. A third 5' end arises from another promoter, P26b, which shows one base pair mismatch with respect to the absolutely conserved -10 sequence. All the other 5' ends arise from RNA processing and/or degradation. Since no other late transcription promoter sites were found within the base plate cluster sequence, we propose that the two overlapping late promoters, P51 and P26a, direct the expression of the T4 base plate gene cluster, included between map coordinates 114,000 and 121,038: P51 directs the transcription of genes 51, 27, 28, 29, 48, and 54 on the rDNA strand and P26a the transcription of genes 26 and 25 on the /DNA strand. This peculiar promoter configuration might account for the low level of transcription of these late genes.

The effects of oral 5-hydroxytryptophan administration on feeding behavior in obese adult female subjects

Nineteen obese female subjects with body mass index ranging between 30 and 40 were included in a double-blind crossover study aimed at evaluating the effects of oral 5-hydroxytryptophan administration on feeding behavior, mood state and weight loss. Either 5-hydroxytryptophan (8 mg/kg/day) or placebo was administered for five weeks during which patients were not prescribed any dietary restrictions. Feeding behavior was investigated by means of a questionnaire designed to establish the onset of anorexia and related symptoms. Food intake was evaluated using a three-day diet diary. BDI, SI, STAI-T, and STAI-S were used to assess mood state. The administration of 5-hydroxytryptophan resulted in no changes in mood state but promoted typical anorexia-related symptoms, decreased food intake and weight loss during the period of observation.

Symmetric transcription of bacteriophage T4 base plate genes

Dot-blot and Northern-blot experiments, using strand-specific RNA probes, show that part of the bacteriophage T4 DNA that codes for six of the base plate structural genes (gp 51, 27, 28, 29, 48 and 54), is transcribed in vivo from both DNA strands. The r DNA strand transcripts contain sequences which are translated into structural proteins. Antisense l strand RNA is about 100 fold less abundant than RNA molecules transcribed from the r DNA strand.

Uptake of amino acids by brain microvessels isolated from rats with experimental chronic renal failure

The neurological disorders seen in patients with chronic renal failure and liver cirrhosis are analogous. Previous in vivo studies have shown that the impaired blood-brain amino acid transport seen in rats with chronic renal failure is similar to that of rats with portocaval anastomosis. To elucidate whether a comparable underlying pathogenic mechanism plays a role in both pathological conditions, blood and brain amino acid levels together with amino acid transport by isolated brain microvessels have been studied in rats with chronic renal failure and in sham-operated rats. Brain microvessels isolated from rats with experimental chronic renal failure showed that the uptake of labeled large neutral amino acid, i.e., leucine or phenylalanine, but not of lysine or alpha-methylaminoisobutyric acid, was significantly increased with respect to sham-operated rats; conversely, the uptake of glutamic acid in rats with chronic renal failure was significantly lower compared with values in controls. Kinetic analysis indicated that this was mainly due to increased exchange transport activity (Vmax) of the L-system, rather than to changes in the affinity (Km) of the carrier system for the relative substrate. These data, together with the significant rise of brain glutamine levels and an increased brain-to-plasma ratio of the sum of large neutral amino acids, are analogous to what was previously observed in rats with portocaval anastomosis.(ABSTRACT TRUNCATED AT 250 WORDS)

The structure of three bacteriophage T4 genes required for tail-tube assembly

Three different protein molecules copurify with T4 tail tubes after the tubes are released from the baseplate by guanidine hydrochloride treatment. These tube-associated proteins (TAPs) are the products of genes 29, 48, and 54. To further investigate the structural roles that these proteins may play in T4 tail assembly we have cloned and sequenced the genes coding for these proteins and have deduced their predicted amino acid sequences. The sequence data reveal a region of amino acid sequence similarity between gp54 and the T4 tail-tube structural protein, gp19. We believe that this region of similarity is significant and consistent with the role gp54 may play in initiating T4 tail-tube polymerization.

Amino acids and hepatic encephalopathy

The consideration of HE and its etiology has undergone a radical turn within the past decade. At present HE is seen in the context of severe metabolic derangements, which failure of the liver, the central biochemical powerhouse of the body, must bring with it. The increased awarenesses on the biochemical mechanisms involved in the pathogenesis of HE have found, step by step, their own place in a complex but consequential mosaic of events, in which amino acid and HE are tightly linked. Clinical and experimental studies are needed to further improve the knowledge in this field, nontheless a certain number of corner-stones can be identified: A profound alteration of the central nervous system neurotransmission is responsible for most, if not all, of the symptoms characterizing HE. The plasma amino acid imbalance observed in cirrhotic patients represents a 'condicio sine qua non' HE may develop. A functional impairment of the amino acid transport systems at the level of the blood-brain barrier seems to play a crucial role in causing deleterious modifications of the synaptic neurotransmission in the central nervous system. The reduction of the brain entry of the "toxic" aromatic amino acids usually obtained by parenteral administration of especially tailored amino acid mixtures is most frequently followed by awakening from HE. In conclusion, most of the results obtained have demonstrated that HE represents a research field in which progresses in the knowledge of some of the pathogenic mechanisms have brought the investigators to new therapeutic approaches which have clearly improved the prognosis of patients suffering from this severe neuropsychiatric syndrome.

Exogenous lipid clearance in compensated liver cirrhosis

The tolerance to exogenous fats has been evaluated in patients with liver cirrhosis. A three-stage lipid clearance test with continuous infusion (3 hr) of a triglyceride emulsion, Intralipid, was performed on 10 patients with well compensated liver cirrhosis and 10 normolipidemic volunteers. During the infusion, blood samples were collected for the measurement of particulate triglycerides (TG) by nephelometry; samples were also collected for total TG, free fatty acids (FFA) and free tryptophan (TRP) determinations. Plasma endogenous triglycerides were calculated as the total minus exogenous, particulate, TG. The fractional removal rate (K2) and the maximal clearing capacity (K1) for exogenous TG were lower in patients than in controls, though a significant difference (p less than 0.05) was found only for K1. Endogenous TG and FFA showed a comparable rise in patients and controls during Intralipid infusion. A significant increase in free TRP was noted in cirrhotics upon maximal infusion rate. It is concluded that: in patients with well compensated liver cirrhosis the maximal clearing capacity (K1) for exogenous TG is impaired. Nonetheless, moderate amounts of fat may be removed at a normal rate from the bloodstream; a normal synthesis rate of exogenous TG may be maintained even in a severely damaged liver; considering the possible role of free TRP in the pathogenesis of hepatic encephalopathy (HE), the use of large amounts of lipids should be discouraged in patients with decompensated liver cirrhosis, or even avoided in those with impending or overt HE.

Use of branched chain amino acids for treating hepatic encephalopathy: clinical experiences

The efficacy of branched chain amino acids in two consecutive clinical studies in patients with severe hepatic encephalopathy was tested. In the preliminary uncontrolled study 19 patients with grade 3-4 hepatic encephalopathy were given an intravenous solution containing leucine 11 g/l, isoleucine 9 g/l, and valine 8.4 g/l in 20% dextrose. A complete recovery of mental state was obtained in all patients in a mean time of 20.5 hours. In a subsequent controlled study 40 patients with grade 3-4 hepatic encephalopathy were randomly assigned to receive intravenous branched chain amino acid in 20% dextrose (group A) or oral lactulose (group B). Twelve patients (70.6%) in group A and eight (47%) in group B regained consciousness in a mean time of 27.6 and 31.5 hours, respectively. The difference in the recovery rate between the two groups, although evident, was not significant. Intravenous branched chain amino acids are thus at least as effective as lactulose in reversing hepatic coma. These data argue strongly in favour of a therapeutic effect of branched chain amino acids in the treatment of hepatic encephalopathy in patients with chronic liver failure.

Plasma tryptophan and anorexia in human cancer

A correlation between anorexia and brain levels of serotonin and tryptophan (TRP) has been reported in tumor-bearing animals. In the present investigation 45 patients with various types of cancer and 13 control subjects were studied. Prior to the study the patients had received no antineoplastic therapy and were unaware of the malignancy of their disease. Feeding behavior was investigated by means of a questionnaire in which the presence of anorexia (A), aversion to meat (MA), taste (TA) or smell (SA) alterations, nausea and/or vomiting (NV) and early satiety (ES) was assessed. Plasma levels of free TRP, the other neutral amino acids (NAA), albumin and non-esterified fatty acids (NEFA) were assayed. Plasma-free TRP was significantly increased in anorectic cancer patients. The free TRP/competing NAA ratio, which might better predict brain TRP levels, was significantly higher in patients with A, MA, TA, SA, NV and ES than in controls or in non-anorectic (NA) cancer patients. These findings seem to confirm that free TRP may play an important role in human cancer anorexia.

Statistical evaluation of the coding capacity of complementary DNA strands

Two independent methods are used to evaluate the protein-coding information content in different classes of DNA sequences. The first method allows to evaluate the statistical relevance of finding unidentified reading frames, longer than 100 codons, on both DNA strands of: a) 117 DNA sequences that code for 142 nuclear proteins; b) 39 stable RNA coding sequences and c) 36 other DNA sequences which include regulatory and as yet unknown function sequences. The finding of 50 reading frames longer than 100 codons (complementary inverted proteins or c.i.p. genes) located on the DNA strand complementary to the protein-coding one is drastically in excess of the number predicted by chance alone. An independent method (testcode) applied to c.i.p. gene sequences, which assigns the probability of coding to a given sequence, predicts that more than 50% of these genes are translated in a functional product. These analyses indicate the existence of a new class of protein-coding genes, located on the DNA sequences complementary to the protein-coding DNA strand.