Spectrum of K ras mutations in Pakistani colorectal cancer patients.

The incidence of colorectal cancer (CRC) is increasing daily worldwide. Although different aspects of CRC have been studied in other parts of the world, relatively little or almost no information is available in Pakistan about different aspects of this disease at the molecular level. The present study was aimed at determining the frequency and prevalence of K ras gene mutations in Pakistani CRC patients. Tissue and blood samples of 150 CRC patients (64% male and 36% female) were used for PCR amplification of K ras and detection of mutations by denaturing gradient gel electrophoresis, restriction fragment length polymorphism analysis, and nucleotide sequencing. The K ras mutation frequency was found to be 13%, and the most prevalent mutations were found at codons 12 and 13. A novel mutation was also found at codon 31. The dominant mutation observed was a G to A transition. Female patients were more susceptible to K ras mutations, and these mutations were predominant in patients with a nonmetastatic stage of CRC. No significant differences in the prevalence of K ras mutations were observed for patient age, gender, or tumor type. It can be inferred from this study that Pakistani CRC patients have a lower frequency of K ras mutations compared to those observed in other parts of the world, and that K ras mutations seemed to be significantly associated with female patients.

Spectrum of K ras mutations in Pakistani colorectal cancer patients

The incidence of colorectal cancer (CRC) is increasing daily worldwide. Although different aspects of CRC have been studied in other parts of the world, relatively little or almost no information is available in Pakistan about different aspects of this disease at the molecular level. The present study was aimed at determining the frequency and prevalence of K ras gene mutations in Pakistani CRC patients. Tissue and blood samples of 150 CRC patients (64% male and 36% female) were used for PCR amplification of K ras and detection of mutations by denaturing gradient gel electrophoresis, restriction fragment length polymorphism analysis, and nucleotide sequencing. The K ras mutation frequency was found to be 13%, and the most prevalent mutations were found at codons 12 and 13. A novel mutation was also found at codon 31. The dominant mutation observed was a G to A transition. Female patients were more susceptible to K ras mutations, and these mutations were predominant in patients with a nonmetastatic stage of CRC. No significant differences in the prevalence of K ras mutations were observed for patient age, gender, or tumor type. It can be inferred from this study that Pakistani CRC patients have a lower frequency of K ras mutations compared to those observed in other parts of the world, and that K ras mutations seemed to be significantly associated with female patients.

Patterns of mortality in patients with motor neurone disease.

OBJECTIVE: Motor neurone disease (MND) is a rapidly fatal condition with survival of less than 4 years. Patients can deteriorate quickly in the preterminal stages resulting in inappropriate resuscitation or admission to intensive care units (ICU) or accident and emergency (A & E). MATERIAL AND METHODS: We looked at patterns of mortality with emphasis on the place of death. A retrospective study was performed of all patients attending an MND clinic, who had died within a 10-year period. RESULTS: Of 179 patients (63 female), 81 patients (45%) died at home, in a hospice or in a nursing home. Sixty-five patients (36%) died in hospital (11 in ICU or A & E). Nine of the latter were previously known to have MND and six admissions were probably avoidable. Most ward patients died of respiratory causes and were treated conservatively. CONCLUSION: The proportion of patients dying in A & E or ICU was small but could have been reduced further. A number of those who died on the wards could probably have been managed conservatively at home. Older patients and those with bulbar disease had a poorer prognosis.

Relationship between supramaximal flow during cough and mortality in motor neurone disease.

The main function of cough is clearance of intrathoracic airways. A normal cough is characterized by a transient increase in expiratory flow above the maximal flow-volume loop envelope, known as cough "spikes". They may be absent in patients with motor neurone disease. The relationship between cough pattern, pulmonary function and survival was studied. Fifty-three patients were recruited (25 bulbar). Vital capacity, maximal inspiratory and expiratory mouth pressures and cough flow/volume curves were performed on all patients, and the presence or absence of spikes were recorded. The primary endpoints were mortality or initiation of ventilatory support over a period of 18 months. Thirty-five patients died over the 18-month period of the study (including the six who were started on noninvasive ventilation). Twelve of the 24 patients with spikes died compared to 23 out of 29 patients without spikes (p<0.05). Patients without spikes were more likely to be bulbar on clinical grounds (p<0.0001) and had poorer lung function. The results showed an association between the absence of cough spikes and increased mortality. However the main determinants of survival in motor neurone disease are age, vital capacity and inspiratory mouth pressure, and it remains to be shown whether regular monitoring of cough conveys any additional advantage.

Sniff nasal inspiratory pressure as a marker of respiratory function in motor neuron disease.

Vital capacity (VC) and maximum mouth pressures are often used to monitor respiratory function in motor neuron disease (MND), but require the use of a mouthpiece. Sniff nasal inspiratory pressure (SNIP) is a simple and reliable means of measuring inspiratory muscle strength; it does not involve the use of a mouthpiece and might therefore be better than VC or mouth pressures for assessing patients with bulbar disease. SNIP, maximum inspiratory (MIP) and expiratory mouth pressure (MEP), VC and arterial carbon dioxide tension (Pa,CO2) were measured in 59 consecutive patients attending a specialist MND clinic. Thirty-one had bulbar involvement on clinical grounds. Both SNIP and VC were inversely related to Pa,CO2 in nonbulbar patients only. Neither MIP nor MEP were related to Pa,CO2. The 10 patients with an elevated Pa,CO2 (>6 kPa) had significantly lower SNIP and VC than normocapnic patients. Sniff nasal inspiratory pressure can be used to monitor respiratory function in motor neuron disease. It is quick and easy for patients to perform, but otherwise appears to offer little advantage over vital capacity measurement. Patients with bulbar disease are often poor at performing sniff nasal inspiratory pressure manoeuvres, possibly because of upper airway collapse or inability to close the mouth completely during the manoeuvre.

Characterisation of the structure and expression of the gene encoding a major female specific polypeptide of Schistosoma mansoni.

A previously described cDNA clone, pSF10, of Schistosoma mansoni encoding the very dominant female specific polypeptide (FSP) has been used to characterize the gene and its expression. The gene is detectable in different isolates of S. mansoni and is estimated to be present in 3 copies per haploid genome. The gene is not sex linked and exhibits neither amplification nor rearrangement concomitant with expression. Expression of the gene by parasites maturing in hamsters is first detected after 5 weeks when the RNA is present at 1/10 the level of that of 6 week worms. Although the FSP gene is specifically and highly expressed by egg laying female worms a corresponding polypeptide produced by the cell-free translation of RNA is not detectable. It was confirmed, however, that pSF10 does indeed encode a mRNA by DNA sequence analysis. The sequence demonstrated a mRNA containing a poly(A) tail and two open reading frames. One reading contains no methionine but is very high (47%) in glycine. This amino acid composition could account for the inability to detect the gene product by cell-free translation in the presence of [35S]methionine.

Resistance to reinfection with Schistosoma haematobium in Gambian children: analysis of their immune responses.

The relationship between reinfection with Schistosoma haematobium and immunological parameters was studied in a group of Gambian children aged from 8 to 13 years. Each individual's exposure to infection was assessed from observations of water contact, cercarial densities and infected snail densities at water contact sites. Eosinophil counts were made and responses to egg antigen (SEA) and adult worm antigen (WWH) measured by ELISA. Low levels of reinfection were associated with a high eosinophil count, high levels of antibodies against WWH and SEA, increased age and low exposure. In a multiple regression analysis of the association of reinfection with eosinophil count, antibody levels, exposure, age and sex, the effects of eosinophil count and exposure were still very significant after allowing for all the other variables. The effects of the antibody levels were close to significance after allowance for exposure and eosinophil count (for WWH: P = 0.09; for SEA: P = 0.07), although the evidence was less clear after additional allowance was made for age and sex. The ability of sera from the children to recognize different parasite antigens was also examined by immunoprecipitation of labelled schistosomulum surface, WWH, SEA and S. haematobium adult worm mRNA in vitro translation products. Schistosomulum surface antigens were recognized by all the sera and there was little variation in this response. There was more variation in their responses to SEA and WWH and a marked heterogeneity in the response to in vitro translation products. However, the pattern of antigen recognition appeared unrelated to susceptibility to reinfection.

Cell-free synthesis of Schistosoma mansoni surface antigens: stage specificity of their expression.

Messenger RNA has been extracted from all stages of the life cycle of the parasitic multicellular helminth Schistosoma mansoni. In vitro translation of these mRNA preparations in rabbit reticulocyte lysates yielded in each case a large number of polypeptides. Immunoprecipitation of translation products either by serum from immune mice or from human patients demonstrated that relatively few, approximately 10, polypeptides are recognised as antigens. Two of the in vitro synthesised antigens, of mol. wts. 22 000 and 14 000, were demonstrated to correspond to schistosomula surface antigens. The expression of these antigens may show stage specificity. Both are readily detected from adult and sporocyst translation products, neither from schistosomula and only the 22 000 antigen from miracidia. This is an unexpected finding since similar polypeptide antigens occur on the surface of schistosomula. These results indicate that not only are schistosomula surface antigens preformed at the preceding sporocyst stage, i.e., within the snail host, but they also remain invariant throughout the life cycle in the vertebrate host. Two other prominent schistosomula surface antigens of mol. wts. 38 000 and 32 000, were not recognised amongst cell-free translation products directed by RNA from any life cycle stage. The demonstration that at least two schistosomula surface antigens are detectable amongst adult mRNA cell-free translation products demonstrates the feasibility of identifying the genes encoding them in cDNA libraries from adult worm mRNA.

Interpretation of hematological and biochemical laboratory data in large-scale, multicenter clinical trials.

The laboratory assessment of drug tolerability is central to a long-term trial. But because of its volume, its multicenter origin, and the importance of nondrug factors, the analysis of these data is complicated. Various methods, i.e., collection of investigators' opinion, comparison of before- and after-treatment means, and analysis of transitions, were found to be unsatisfactory. A fourth method, described in this paper, seems to be more promising. An initial computer screening of the laboratory data is conducted to identify all patients with the potentially clinically relevant laboratory abnormalities. Each laboratory abnormally is then examined by the pharmaceutical physician with regard to the patient's sex and age, the trial diagnosis, concomitant and intercurrent illnesses, concurrent medication, unwanted effects, and other laboratory results, and each result is assigned a probable etiology according to a pre-defined classification system. By this method it is then possible to compare the frequency and severity of possible or probable drug-related laboratory abnormalities occurring with the various trial drugs. Our opinion regarding the importance of using this method would appear justified by the fact that a possible or probable drug effect was considered to have been responsible for only 15 per cent (112/760) of the potentially clinically relevant abnormal tests reported.