Induction of a selective and persistent extravasation of neutrophils into the peritoneal cavity by tryptase mouse mast cell protease 6

Recombinant mouse mast cell protease 6 (mMCP-6) was generated to study the role of this tryptase in inflammatory reactions. Seven to forty-eight hours after the i.p. injection of recombinant mMCP-6 into BALB/c, mast cell-deficient WCB6F1-Sl/Sl(d), C5-deficient, or mMCP-5-null mice, the number of neutrophils in the peritoneal cavity of each animal increased significantly by >50-fold. The failure of the closely related recombinant tryptase mMCP-7 to induce a comparable peritonitis indicates that the substrate specificities of the two tryptases are very different. Unlike most forms of acute inflammation, the mMCP-6-mediated peritonitis was relatively long lasting and neutrophil specific. Mouse MCP-6 did not induce neutrophil chemotaxis directly in an in vitro assay, but did promote chemotaxis of the leukocyte in the presence of endothelial cells. Mouse MCP-6 did not induce cultured human endothelial cells to express TNF-alpha, RANTES, IL-1alpha, or IL-6. However, the tryptase induced endothelial cells to express large amounts of IL-8 continually over a 40-h period. Neither enzymatically active mMCP-7 nor enzymatically inactive pro-mMCP-6 was able to induce endothelial cells to increase their expression of IL-8. Although the mechanism by which mMCP-6 induces neutrophil accumulation in tissues remains to be determined, the finding that mMCP-6 induces cultured human endothelial cells to selectively release large amounts of IL-8 raises the possibility that this tryptase regulates the steady state levels of neutrophil-specific chemokines in vivo during mast cell-mediated inflammatory events.

[Tolerance to interferon beta-1b amongst patients with remittent recurrent multiple sclerosis after more than one year of treatment]

INTRODUCTION

Interferon beta-1b modifies the natural history of the remittent recurrent forms of multiple sclerosis. An analysis was made of its efficiency, tolerance and adverse effects on patients with over one year of treatment.

MATERIAL AND METHODS

16 patients were studied (10 women, 6 men) with ages between 19 and 51 years, incapacity scale (EDSS) 2.61 +/- 1.07 and an annual rate of outbreaks before treatment of 1.65 +/- 0.25, who received 4 MUI/48 h/s.c. of interferon beta-1b x 15 days, afterwards continuing with 8 MUI/48 h/s.c. Corticoids were associated in four cases. Biochemical controls and mass neurological evaluations were carried out as well as a watch being kept for clinical and analytical secondary effects.

RESULTS

The annual rate for outbreaks was 0.68 +/- 0.29. Amongst the most frequent adverse effects the pseudoflu syndrome was notable (87%), with an average duration of 10.46 +/- 1.4 weeks, well tolerated with paracetamol. The local reactions (87%) were light and not related to the zone of injection. The patients experienced a sensation of fatigue following the injection in 50% of the cases, although in only one case did this reach a moderate intensity. Analytical alterations were found to be 43.7%, always within the margins of grade 1 of the clinical toxicity scale. With one patient developed an acute depressive syndrome, during which treatment was interrupted, later restarted at half the maintenance dosage.

CONCLUSIONS

In our series, just as in other studies, pseudoflu syndrome and local reactions were the most frequent secondary effects. Both complications are light, of brief duration and well tolerated by the patients.

[Activity of Dipernoids isolated from Azorella compacta (Llareta) on Trypanosoma cruzi amastigotes]

The trypanocidad activity against amastigote forms of SPA-14, Tulahuen and G strains and CL Brener clone of Trypanosoma cruzi of diterpenoids isolated from Azorella compacta, Phil. (Llareta), a plant with ethnomedicinal prestige from prespanish age, was investigated. Amastigocidal activity was shown in azorellanol (2), diterpene isolated by first time, with an inhibitory concentration 50 (IC50) that varied between 60 M (CL Brener clone) and 84 M (SPA-14 strain), and in mulin -11,13 -dien-20-oico acid (5) with IC50 between 41 microM (G strain) and 87 mM (CL Brener clone). The cytotoxicity levels of both compounds against Hela and Vero cells and macrophages J144 are lower than nifurtimox and similar to gentian violet.

[Neuromuscular disorders in critically ill patients]

INTRODUCTION AND OBJECTIVE

Critically ill patients admitted to the Intensive Care Unit (ICU) often develop neuromuscular disorders. The objective of this study was to diagnose these and determine the causes.

MATERIAL AND METHODS

We present a series of 13 critically ill patients who developed weakness or paresia, reduced or absent ROT and normal brain stem reflexes, in whom ENG and EMG studies were done in EESS and II which were considered together with data from general laboratory analysis, radiological and microbiological examinations, medication given and posterior clinical course of the patient. Muscle biopsy was not done in any patient.

RESULTS

All the patients were intubated, with signs of sepsis, multiple-organ failure and malnutrition. All had received cortico-steroids and amino-glucosides and 8/13 neuromuscular blockers. Neurophysiological study showed that in all cases there was axon type neuropathy, mainly motor and in the lower limbs. Fifty four percent of the patients died. The neuropathy improved in the others.

CONCLUSIONS

Critically ill patients often have axon type neuropathy. In our series, the causes of this were sepsis and multiple organ failure. It is important that this pathology be ruled out in the critically ill patient whom it is difficult to disintubate and/or has generalized muscle weakness.

[Andermann syndrome: presentation of a case]

INTRODUCTION

Peripheral neuropathy with agenesis of the corpus callosum (or Andermann's syndrome) is a hereditary autosomal recessive disorder rarely found outside certain regions of Quebec Province (Canada). It is associated with mental retardation and various dysmorphic changes. Deterioration is usually progressive with loss of motor skills, development of scoliosis during adolescence, tendency to behaviour disorders and death during the third decade (approximately).

CLINICAL CASE

We present a 13 year old girl diagnosed as having the spastic tetraparesic type of PCI, who was sent to us so that we could reconsider the diagnosis in view of the atypical course of the illness. The patient had an unusual phenotype with dysmorphic changes (mainly facial), axial hypotonia with flexion-retraction of the hands, generalized arreflexia, neurogenic bladder, skin changes with ulcers on the legs and mental retardation. Neurophysiological studies showed a predominantly motor polyneuropathy. There were signs of axonal neuropathy on both sural nerve and skeletal muscle biopsies. The clinical features, phenotype, microcephaly with agenesis of the corpus callosum and a posterior fossa cyst, associated with spinal atrophy indicated the diagnosis of Andermann's syndrome.

CONCLUSIONS

This case is of interest in view of the exceptional rarity of Andermann's syndrome in our population.

[Cercaria chaetotaxy of 2 Venezuelan strains of Schistosoma mansoni]

By means of the silver impregnation of two lots of Schistosoma mansoni cercariae belonging to the strains: JR (32 cercariae) and C5 (45 cercariae), the number and pattern of disposition of the argentophillic papillae were determined with the following results: Average number of total dorsal papillae: 12.1 (JR strain) and 12.0 (C5 strain); the variation coefficients in this surface were less than 4% (JR strain) and bigger in JR than C5 strain. Average number of total ventral papillae: 12.15 (JR), 11.97 (C5); maximum value of the variation coefficient: 6.4% (JR), higher in JR than C5 strain. When the ventral surface was classified in four quadrants, the average number of papillae by quadrant was: quadrant A: 1.15 (JR) and 1.06 (C5): B: 1.06 (JR) and 1 (C5); C: 4.97 (JR) and 4.96 (C5); D: 5.03 (JR) and 4.98 (C5). The variation coefficients were higher in the A and B ventral quadrants, reaching maximum values of 31.9%, and 61.0% for the posterior quadrants C and D. When the ventral surface was divided in three equal parts for determining the position of the most variable papillae of this area, the greatest value of the variation coefficients obtained were for the 2nd thirds of the cercariae: 89.8% and 76.8% for C5 strain and 43.5% and 56.8% for JR strain. In relation to the total lateral papillae, the average numbers were: 17.0 (JR) and 16.6 (C5), with a maximum value of variation coefficient of (8.1% (C5). The average total number of papillae of the tail were: 25.6 (JR) and 26.1 (C5) for the ventral surface and 20.72 (JR) and 21.33 (C5) for the dorsal papillae. The comparison between the percents of the cercariae of two S. mansoni strains with more than 1 papillae on the anterior ventral quadrants A or B (94% JR and 34% C5), resulted with significant differences (P < 0.05).

Mapping of the antigenic determinants of the Leishmania infantum gp63 protein recognized by antibodies elicited during canine visceral leishmaniasis

The gp63 gene encoding the major surface antigen of Leishmania infantum has been cloned and sequenced. In spite of the overall sequence homology with the gp63 genes from other Leishmania species, particularly with the constitutively expressed Leishmania chagasi Gp63 gene, the carboxy-terminal ends of these genes are clearly divergent (62% homology). To study the prevalence of anti-gp63 antibodies in the sera from dogs with visceral leishmaniasis, a recombinant L. infantum gp63 protein was expressed in Escherichia coli. It was found that 100% of the sera from these dogs recognized the recombinant gp63 protein, suggesting that it must function as a potent B cell immunogen during natural canine visceral leishmaniasis. However, heterogeneity in the level of response was observed. Fine mapping of the antigenic determinants was performed by means of 6 overlapping subfragments of the gp63 protein and by the use of a library of synthetic peptides. The data showed that there is some degree of immunological restriction in the recognition of the protein since reactivity was observed preferentially against the most divergent region. The epitope mapping of this region showed 2 immunodominant peptides the response to which seems to be preferentially of the IgG2 type.

Conservative treatment versus antireflux surgery in Barrett's oesophagus: long-term results of a prospective study

The results obtained for the treatment of 59 patients diagnosed with Barrett's oesophagus, randomized to receive medical treatment (n = 27) or antireflux surgery (n = 32) were assessed prospectively. Median follow-up for the patients undergoing medical treatment was 4 (range 1-11) years and for patients undergoing surgical treatment 5 (range 1-11) years. Satisfactory symptomatic control (excellent to good results) was achieved in 24 patients after medical therapy and in 29 after antireflux surgery. The proportion of patients with persistent inflammatory lesions (54 per cent) and persistent or recurrent stenosis (47 per cent) was significantly higher after conservative treatment than after surgery (5 and 15 per cent, respectively). A decrease in the length of the segment of columnar mucosa was observed in eight of the patients who underwent antireflux surgery, and in only two of those given medical therapy. Conversely, an upward progression of the columnar lining was more frequent in the latter group (11 versus three). Mild dysplasia was observed in five patients, all from the group undergoing medical treatment. Severe dysplasia was detected in two patients, one undergoing medical treatment and the other following surgical therapy, in whom an antireflux procedure had failed previously. Both patients underwent oesophageal resection, with confirmation of a carcinoma in situ. The patients in whom antireflux surgery proved effective showed no dysplastic change or progression to adenocarcinoma. These results, despite the small number of patients and methodological limitations, question the systematic conservative approach in the initial management of patients with Barrett's oesophagus.

Synergistic neurite-outgrowth promoting activity of two related axonal proteins, Bravo/Nr-CAM and G4/Ng-CAM in chicken retinal explants

In the developing chicken retina, optic fibres migrating to the tectum express on their surfaces several cell adhesion molecules, including Bravo/Nr-CAM and G4/Nr-CAM and G4/Ng-CAM. We have previously described differential distribution along the retinotectal projection and differential modulation by environmental cues for Bravo and G4 and here we further compare the characteristics of these immunoglobulin superfamily molecules. From day 6 of embryonic development (E6) to 20 (E20), Bravo and G4 were found to coexist in the retinal optic fibre layer. However, while G4 staining was confined to that layer, as development proceeded Bravo staining spread to plexiform layers and some radial structures of the retina. G4 displayed a dose-dependent neurite-outgrowth promoting activity for E6 retinal explants, while Bravo did not support neurite growth. Surprisingly, when the retinal explants were grown on mixtures of the two molecules, a much more vigorous growth of neurites was seen, revealing a synergistic effect. We propose that Bravo and G4, as well as other axonal surface molecules, affect axonal growth in different ways when they are present in combination than when they are alone.

Domestic vectors of Chagas' disease in three rural communities of Nicaragua

A triatomine survey was conducted in three rural settlements of Nicaragua (Santa Rosa, Quebrada Honda and Poneloya) where Chagas' disease is endemic, to determine rates of house infestation, evaluate the housing condition and to assess the performance of the Maria sensor box in detection of domestic vectors. A total of 184 households were selected and vectors were sought by the methods of timed manual capture and by sensor boxes. The solve vectors species found in this study was Triatoma dimidiata. Of the examined bugs 50, 60 and 33%, in the respective communities, were infected with T. cruzi. The rates of house infestation as determined by manual capture and sensor boxes were respectively, 48.3% and 54.2% in Santa Rosa, 29.8% and 51.2% in Quebrada Honda and in Poneloya 3.8 and 5.9% with significant difference between the methods in Quebrada Honda. When compared with the manual capture, the Maria sensor box detected vectors in 71.4% of positive houses in two of the communities but also was able to detect bugs in 39.3% and 41.1% of houses where manual capture had been negative. Housing condition was evaluated according to three structural parameters, in this way, in the first community 79.2% of houses were classified as bad, 20.8% as regular; in the second one 42.5% were bad and 57.5% regular, whereas in the third 62.5% of the houses were regular. Rates of infestation did not differ greatly between the different housing conditions. Our results show that the sensor box is as efficient as manual capture and could be implemented in our country.

[Anal incontinence in patients with rectal neoplasms previous to surgical intervention]

HYPOTHESIS

Patients with rectal carcinoma may have anal continence disorders before the operation, in relation to age.

AIM

To evaluate the anorectal function in a consecutive sample of patients with rectal carcinoma before the operation.

MATERIAL AND METHODS

56 consecutive patients with rectal carcinoma were studied and classified into two groups according to anal continence: continent and incontinent. Anorectal function were evaluated in all patients: Perineometry (perineal measurements at rest and during a straining effort), Anal manometry (anal pressures and rectal capacity), Pudendal nerve terminal motor latency.

STATISTICAL ANALYSIS

quantitative data: -test (confidence interval), qualitative data: Fischer exact test.

RESULTS

Anal continence: continent 41, incontinent 15. All patients with anal incontinence were more than 60 years old (p<0.01). Mean age: continent 61.3 +/- 12.4, incontinent 74.3 +/- 6 (p<0.01, CI 8.02-17.98). Perineal measurement: at rest: continent 2.97 +/- 0.69. incontinent 2.54 +/- 0.56 (p<0.05, CI 0.03-0.83), with straining effort: continent 1.37 +/- 0.86, incontinent 0.81 +/- 0.92 (p < 0.05, CI 0.03 - 1.86). Pudendal latency: continent 1.9 +/- 0.3, incontinent 2.3 +/- 0.5 (p<0.01, CI 0.11-0.69). There was no significant difference in the manometric data.

CONCLUSION

Patients with rectal carcinoma have preoperative anal continence alterations, in relation to pelvic disorders and age.

Factors involved in the return of peristalsis in patients with achalasia of the cardia after Heller's myotomy

OBJECTIVE

To assess the reappearance of peristalsis in a group of 45 patients with achalasia of the cardia undergoing surgery and to analyze the factors involved in this phenomenon.

METHODS

According to the postoperative manometric data, the 45 patients were divided into two groups, depending on whether or not they presented a return of peristalsis. A statistical comparison of age, sex, duration of the disease, pre- and postoperative radiological diameter of the esophagus, classic or vigorous nature of the achalasia, and manometric data of the lower esophageal sphincter and esophageal body was made.

RESULTS

In 46.6% of the patients, peristalsis returned to the upper esophagus, and 100% of the waves were progressive; in 24.4%, peristalsis returned to the middle third also, but only 50% of the waves were progressive; and in 8.8% (four patients), peristalic activity returned to the whole esophagus, but only 40% of the waves were progressive. The group of patients with a return of peristalsis had a shorter duration of dysphagia, less preoperative dilation of the esophagus, and a greater contractile activity of the esophageal body.

CONCLUSIONS

Return of peristalsis is a frequent phenomenon after myotomy in patients with achalasia of the cardia, especially in cases of short clinical evolution, little esophageal dilation, and a conserved contractile capacity, although its accurate production mechanism is unknown.

The Leishmania infantum histone H3 possesses an extremely divergent N-terminal domain

The isolation of a Leishmania cDNA clone coding for an antigen identified as the histone H3 is described. The nucleotide sequence of the cDNA predicts that the Leishmania histone H3 contains 129 residues and that it has a molecular mass of 14,620 Da. Comparison of the amino acid sequence with the consensus sequence of the eukaryotic histone H3 shows that the Leishmania protein has a highly conserved globular region and an extremely divergent amino-terminal portion.

Induction of axonal growth by heterophilic interactions between the cell surface recognition proteins F11 and Nr-CAM/Bravo

F11 and Nr-CAM/Bravo are two axon-associated glycoproteins belonging to different subgroups of the immunoglobulin superfamily. In this report we have investigated the interaction of both proteins using neurite outgrowth and binding assays. Antibody blocking experiments demonstrate that neurite extension of tectal cells on immobilized F11 is mediated by Nr-CAM/Bravo. Binding studies further reveal a direct heterophilic interaction between F11 and Nr-CAM/Bravo. This activity can be mapped to the amino-terminal second or third immunoglobulin-like domain within F11 with domain-specific monoclonal antibodies and deletion mutant proteins expressed on COS cells. Furthermore, perturbation experiments with domain-specific monoclonal antibodies demonstrate that this region is required for adhesion and neurite extension.

Correlation between esophageal motility and 24-hour pH recording in patients with gastroesophageal reflux

The relationship between manometric and pH-metric data was studied in a group of 50 patients with symptoms of gastroesophageal reflux. Using a multiple regression analysis, we found that the total percentage of reflux was significantly correlated to the infradiaphragmatic length and resting pressure of the lower esophageal sphincter and also to the mean amplitude of the contractile waves of the distal esophagus, thus revealing the important role of these factors in the antireflux mechanism. When the patients were divided into groups according to their manometric characteristics and the values of the various pH-metric parameters between these groups compared using a one-way analysis of variance, we found that the amplitude of the contractile waves and the percentage of deglutitions without response were related not only to the total percentage of reflux but also to the number of reflux episodes of greater than 5 min duration and to the duration of the longest episode. This shows that prolonged exposure of the esophageal mucosa to the refluxed material may be due, in part, to an alteration in the capacity for esophageal clearing.

Can pH recordings suggest defective esophageal peristalsis in patients with gastroesophageal reflux?

The data provided by 24-h pH monitoring in 40 patients with gastroesophageal reflux, divided in three groups in accordance with esophageal motor pattern, were compared. Patients with hypomotility had significantly greater reflux rates than those with normal motility or hypermotility, if we consider both total time with pH < 4 and time with pH < 4 corresponding to episodes of > 5 min duration. We conclude that when 24-h pH monitoring shows very high reflux rates, basically corresponding to episodes lasting > 5 min, we should suspect the presence of defective esophageal peristalsis, which must be confirmed with a manometric study.

Reversible achalasia-like motor pattern of esophageal body secondary to postoperative stricture of gastroesophageal junction

Two cases are presented of benign stenosis of the cardia secondary to fibrosis following antireflux surgery in which the patients developed a motor alteration in the esophageal body similar to that of achalasia of the cardia. There was a complete absence of contractions in one patient, which had developed over a long period of time, and a vigorous pattern in the other patient, which had evolved over a short period. In both cases, after surgical treatment of the stenosis, normal motility in the esophageal body returned.

Impaired atrial natriuretic factor systemic clearance contributes to its higher levels in uremia

To evaluate the interaction between plasma levels and the systemic uptake of atrial natriuretic factor (ANF) with thyroid hormone levels during acute renal failure (ARF), seven groups of rats were analyzed: Group 1, Controls (C); Group 2, ARF; Group 3, filtering kidney with uremia; Group 4, ARF with thyroxine (T4) supplement (ARF + T4); Group 5, thyroidectomy (Tx); Group 6, ARF on Tx rats (Tx + ARF); Group 7, Tx + ARF supplemented with T4 (Tx + ARF + T4). Plasma creatinine (Cr), urea, T4, blood volume, and ANF were measured; ANF half-life (ANF t1/2; expressed in seconds) was calculated. Rats with ARF developed uremia (Cr, 377 +/- 58 versus 41 +/- 5 mumol/L), significant reduction in T4 (40 +/- 4 versus 89.2 +/- 6 nmol/L). elevation of ANF (287.7 +/- 35 versus 60.9 +/- 8 fmol/mL), and lengthening of ANF t1/2 (69.7 +/- 8 versus 37.2 +/- 6 s) compared with C (P less than 0.01). T4 supplements to ARF rats resulted in a lesser degree of uremia (Cr, 283 +/- 27; P less than 0.05) and normalization of ANF t1/2 (31.4 +/- 5); however, ANF levels remained higher than C (100.4 +/- 11.4 versus 60.9 +/- 8; P less than 0.01). Tx by itself did not change either parameter. The filtering kidney with uremia group developed mild uremia (Cr, 199 +/- 8), T4 fell (58 +/- 8), ANF levels rose (83.4 +/- 5.4), and ANF t1/2 was prolonged (54.5 +/- 12). Tx before ARF doubled the ANF level and lengthened ANF t1/2 similarly than in ARF. T4 addition (Tx + ARF + T4) normalized ANF t1/2 (29.8 +/- 3) in spite of a persistently high ANF (145.7 +/- 21). Blood volume did not change in any group.(ABSTRACT TRUNCATED AT 250 WORDS)

Outreach to injecting drug users and female sexual partners of drug users on the lower east side of New York City

In 1984, outreach to injecting drug users and their female sexual partners was initiated as part of HIV behavioral research projects. HIV, health, drug treatment and family planning information and services were provided in addition to recruiting subjects to the research program. Such outreach also poses certain problems--especially potential disruption of neighborhood day-to-day life and clashes with police. This paper discusses an outreach program to injecting drug users and their female sexual partners that was initiated in New York City to provide HIV-related information and services. We examine the successes of the program and problems that were involved in conducting outreach to persons who are typically not accessible through formal institutional channels.

Long-term results of Nissen fundoplication in reflux esophagitis without strictures. Clinical, endoscopic, and pH-metric evaluation

The present paper evaluates the efficiency of Nissen fundoplication as an antireflux technique in a series of 51 patients with different grades of esophagitis. Follow-up time averaged 6.6 years. The evaluation includes a clinical assessment, endoscopic study, and 24-hr pH monitoring. The results reveal an acceptable rate of recurrences, with clinical (9.8%) being less frequent than endoscopic (13.7%) or pH-metric (19.6%) recurrences. Side effects appeared in 37.3% of the patients (mainly inability to belch or vomit, and postprandial fullness), which were mild and transitory in most cases. Nissen fundoplication proved effective in controlling long-term gastroesophageal reflux, as over 80% of the patients presented an excellent-to-good clinical situation, without or with minimal digestive consequences.

Colonic motility: electric and manometric description of mass movement

"Mass movement" was described at the beginning of the century by radiologists who occasionally observed how, during their explorations, barium was transported suddenly from one section of the colon to another. In the present study we wanted to center our attention on electromechanical activities accompanying large evacuations via the colostomy, as we believe that they are an expression in myoelectric and pressure terms of the "mass phenomenon" described by radiologists. To do this, we designed an electromyographic recording probe to which we attached a conventional microtransducer probe, joining them by suction. With this method we made 24-hour recordings in eight patients with sigmoid colostomy. We witnessed five large evacuations. When the electric and pressure activities that occurred a few minutes before the evacuation were analyzed, we observed that there were two clearly different phases. The first, which we call "Preliminary Phenomenon," consists of a series of contractions and spiking potentials averaging 5.6 minutes (SD 2.22); after this the "Big Contraction" appears, with mean pressure values of 127 mm Hg (SD 38.77) and mean electric values of 10.6 mV. The duration of this phenomenon averaged 24.93 seconds (SD 6.19), recorded almost simultaneously at the three recording sites studied. There is no doubt that these electro-pressure phenomena resulted in a mass transport, as we observed an intense evacuation via the colostomy in the five patients.

Sequence and expression of the Drosophila phenylalanine hydroxylase mRNA

We report the cloning, nucleotide (nt) sequence and expression of the cDNA (pah) encoding phenylalanine hydroxylase (PAH) of Drosophila melanogaster. The strong hybridization signals observed in genomic blots when D. melanogaster DNA was probed with 32P-labeled human pah cDNA, indicated the existence of a high degree of sequence similarity between the pah genes of both species. The length of the pah genomic fragment is about 30 to 40 kb. The cDNA contains 84 bp of the 5'-untranslated region, 1359 bp of the protein-coding region and 87 bp of the 3' region, with only one polyadenylation signal. The isolated cDNA is probably full-length, since the size of the D. melanogaster PAH mRNA is 1.5 kb. At the nt level, the similarity of the D. melanogaster cDNA with human and rat pah cDNAs is 57.9% and 58.1%, respectively. The highest similarities are restricted to the nt sequence coding for the presumed hydroxylation domain. There is no nt sequence similarity between the first three exons of the human pah gene and an equivalent fraction of the D. melanogaster pah gene. At the amino acid (aa) level, the similarity in the presumed hydroxylation domain is 88.5%, in which two motifs of the structure AGLLSSXXXL are found, where X represents any aa. It was interesting to notice the conservation of aa 408, 311 and 280, where mutations are associated with phenylketonuria in humans. We observed, moreover, that, as it occurs in humans and rats, the expression of the D. melanogaster pah gene is tissue-specific and temporally regulated.