Extrahepatic biliary atresia in Saudi Arabia: the importance of early diagnosis and referral

OBJECTIVE

A retrospective analysis of the medical records of children who were managed for extrahepatic biliary atresia (EHBA) over a 6-year period.

MATERIALS AND METHODS

Twelve children were managed at King Fahad National Guard Hospital with a diagnosis of extrahepatic biliary atresia from January 1993 through December 1998. The data obtained included age, sex, clinical presentation, age at referral, investigations, management, complications and follow-up.

RESULTS

There were 7 males and 5 females with age of onset of jaundice ranging from 3 days to 42 days (mean 10 days). The mean age at referral was 17 weeks (range 6-49 weeks). Kasai Portoenterostomy (PE) was performed in 7 infants and the mean age at surgery was 8 weeks (range 7 to 10.5 weeks). Four children could not undergo Kasai PE because they were more than 20 weeks old and 1 child although 10 weeks old had extensive liver cirrhosis and was considered not suitable for the procedure. One child who had primary liver transplant outside the Kingdom and 4 children who had Kasai PE are still alive. Seven children are lost to follow-up and are probably dead.

CONCLUSION

The incidence of EHBA in Saudi Arabia is unknown and the disease is probably rare based on our review. Although jaundice, pale stools and dark urine were observed in early infancy, referral was always late. Public and health professional's awareness of the clinical features of EHBA is important in early identification of infants and early referral. Starting paediatric hepatobiliary centers in Saudi Arabia will improve the management of these cases.

Evaluation of the school supplementary feeding program in peninsular malaysia

This study was conducted to evaluate the implementation of the School Supplement Feeding Program (SSFP) among primary school in terms of financial management and budget disbursement, food preparation, selection of menus and nutrient content of food served. A total of 129 schools comprising 77 national type, 31 Chinese and 21 Tamil vernacular schools in four different regions (northern, eastern, central and southern) of Peninsular Malaysia were selected for this study. The results of this cross-sectional study showed a need to improve the budget disbursement to schools. Most of the schools followed the guidelines provided by the Ministry of Education for selection of eligible children. The quality of food prepared by contracted (local community members) and voluntary (teachers) operators. The use of 10 recommended menus provided for a 2-week cycle by most of the schools has shown increased acceptance and less monotonous feeling towards the food among the children. Nutrient content of food served increased relatively with an increase in budget from RM0.45 to RM0.80 per child. Parents surveyed indicated that the program should continue as this will keep children from low income families from being hungry during school hours. A continued process of monitoring and evaluation is necessary to improve its implementation.

Turcot's syndrome in an Arab child

A 12 year old female child of Arab origin presented with chronic bloody diarrhoea and growth failure. Physical examination confirmed a growth failure and cafe-au-lait patches. Colonoscopy and colon biopsies showed adenocarcinoma of the colon and laparotomy confirmed metastases to the liver. A diagnosis of Turcot's Syndrome was entertained in this child.

The reproducibility of patch tests

There is conflicting evidence regarding the reproducibility of patch testing. Discordant results have been reported in up to 44% of cases. The clinical relevance of these discordant patch tests has not been previously assessed. We studied 383 consecutive patients receiving simultaneous duplicate patch testing on opposite sides of the upper back with 10 allergens from the European standard series. Completely discordant patch tests-a negative test on one side with a positive test on the opposite side-were recorded in 30 (8%) patients. Two patients had discordant tests to two of the allergens; 28 had discordant reactions to one allergen. Completely discordant tests were recorded for nickel in 10 (3%) patients, balsam of Peru in two (0.5%), thiomersal in one (0.3%), cobalt in four (1%), paraphenylenediamine in three (0.8%), fragrance mix in two (0.5%), formaldehyde in four (1%), potassium dichromate in two (0.5%), lanolin in three (0.8%) and Kathon CG in one (0.3%). Of those patients with completely discordant patch tests, the allergen was deemed to be a true positive in 11 (3% of total) cases and of possible relevance in a further three. The allergen was felt to be relevant to the presenting complaint in seven (2% of total) patients.

Spinobulbar muscular atrophy: polyglutamine-expanded androgen receptor is proteolytically resistant in vitro and processed abnormally in transfected cells

The neuronotoxicity of genes with expanded CAG repeats is most likely mediated by their respective polyglutamine (Gln)-expanded gene products. Gln- expanded portions of these products may be sufficient, or necessary, for pathogenesis. We tested whether a Gln-expanded human androgen receptor (AR) is structurally altered, so that it allows for the proteolytic generation of a potentially pathogenic portion that may be resistant to further degradation. We found, in vitro , that a Gln-expanded AR is more proteolytically resistant than normal, and that it yields a distinct set of Gln-expanded fragments even after extended proteolysis in the presence of 2 M urea. Furthermore, COS cells transfected with CAG-expanded AR cDNA generate an aberrant, nuclear-associated 75 kDa derivative containing the Gln-expanded tract. They are also twice as likely to die by 24 h apoptotically than those transfected with normal AR cDNA. Our data support the notion that an unconventional derivative of the Gln- expanded AR is a component of the proximate motor neuronopathic agent in spinobulbar muscular atrophy. They also focus attention on two ways in which neuronotoxic derivatives may originate from various Gln-expanded proteins: (i) generation of an unusual derivative that is pathogenic de novo ; and (ii) the toxic accumulation of a normal derivative because of an inability to dispose of it.

Rhabdoid transformation of tumor cells in meningiomas: a histologic indication of increased proliferative activity: report of four cases

Four cases of meningeal tumors in adults (ages ranging from 28 to 84 years) are presented. All had the typical gross appearance of meningiomas at operation. In three tumors, areas of meningothelial or fibroblastic meningiomas showed transition to cell groups of the rhabdoid type. In the fourth case only rhabdoid cells were encountered, possibly representing a total "take-over" of a meningioma by rhabdoid elements. In the three cases with mixed pattern, the rhabdoid cells showed more anaplasia and atypism than the conventional meningiomatous elements. In case 3 this was expressed by very high MIB-1 positivity in the rhabdoid cells and absence of same in the fibroblastic meningiomatous elements. These cases (the first three with certainty, the fourth with a strong likelihood) indicate that the phenotypic changes to cells with "rhabdoid" morphology may involve meningiomas and that such change is associated with aggressive biologic and clinical behavior of the tumors showing this type of alteration.

Allergy to phosphorus sesquisulfide: 0.5% pet. is a more appropriate concentration for patch testing

Patch testing was performed with phosphorus sesquisulfide P4S3 in 2 groups containing equal numbers of patients using different concentrations (0.5% P4S3 in pet. and 1% P4S3 in pet., the usual suggested test concentration as recommended by the International Contact Dermatitis Research Group). We found that there was a statistically significant increase in the number of clinically irrelevant irritant reactions in the group tested with the concentration (chi 2 = 16, p < 0.0004). We recommend that patch testing with phosphorous sesquisulfide should be at a reduced concentration of 0.5% pet.

Lipoprotein(a), tissue plasminogen activator and plasminogen activator inhibitor 1 levels in hyperlipidaemic patients in Kuwait

Plasma levels of lipoprotein(a) [Lp(a)], tissue plasminogen activator (tPA) and plasminogen activator inhibitor type 1 (PAI-1) were assessed in addition to anthropometry and levels of glucose, total cholesterol, triglycerides, high-density lipoprotein (HDL), low-density lipoprotein (LDL) and apo A1 and B in 73 patients (36 men and 37 women) with primary hyperlipidaemia (group NDHL) in Kuwait. Lp(a) levels (212 mg L-1, 8-600 mg L-1, median and range) were similar to those obtained in a matched group of 32 non-insulin-dependent diabetes mellitus (NIDDM) patients with hyperlipidaemia (218 mg L-1, 50-610 mg L-1) and slightly higher, although not significantly so (P = 0.06), than levels seen in 68 healthy normolipidaemic control subjects (182 mg L-1, 70-488 mg L-1). tPA levels (8.4 ng mL-1, 3.8-18.4 ng mL-1, median and range) in group NDHL were lower than in the diabetic group (11.4 ng mL-1, 5.2-14.2 ng mL-1) but higher than in the healthy control subjects (7.4 ng mL-1, 2.8-12.6 ng mL-1). PAI-1 levels in group NDHL (40.4 ng mL-1, 8.6-55 ng mL-1, median and range) were higher than in the control subjects (32.5 ng mL-1, 14.6-46.4 ng mL-1) but lower than in diabetic patients (43.8 ng mL-1, 15.6-55 ng mL-1). Hyperlipidaemia phenotype (hypercholesterolaemia or hypertriglyceridaemia) did not influence tPA and PAI-1 levels, but Lp(a) levels were significantly lower with hypertriglyceridaemia. Gender, cigarette smoking and racial origin (Kuwaitis, other Arabs or South Asians) did not affect Lp(a), tPA and PAI-1 levels, but tPA levels were higher in postmenopausal subjects. Low-density lipoprotein (LDL) levels (whether in total cholesterol or as apo B) correlated significantly (P < 0.05) with Lp(a) levels. tPA levels were correlated with age and the plasma levels of glucose and uric acid (P < 0.05); this correlation with glucose may explain the high levels associated with diabetes, whereas the age association might account not only for the differences observed between group NDHL and the younger control group but also for the higher levels in the postmenopausal women. PAI-1 levels correlated with tPA and triglyceride (TG) levels in the groups of subjects (normo- and hyperlipidaemic). In the normolipidaemic control group, the significant associations of tPA and PAI-1 were with body mass, expressed as the body mass index or the waist-hip ratio. These results suggest that different factors influence the plasma levels of the prothrombotic factors Lp(a), tPA and PAI-1 in healthy control subjects and in patients with hyperlipidaemia. In the latter, hyperlipidaemia phenotype, age, glycaemic status and uric acid levels are important determinants of the levels of these prothrombotic variables, whereas in the healthy, young control population, body mass was the single important association with tPA and PAI-1.

Lead exposure among Malaysian school children using delta-aminolevulinic acid as an indicator

A study on lead exposure among school children aged between 7 and 12 years from Kajang and Sepang in the state of Selangor, Malaysia was carried out using delta-aminolevulinic acid (delta-ALA) levels in the urine as an index. The delta-ALA levels in urine were linked to variables which could contribute to lead exposure. Out of 1628 school children studied [Kajang (43.5%) and Sepang (56.5%)], only 194 subjects (16 and 8.8% from Kajang and Sepang, respectively) had urinary delta-ALA levels between 0.6 and 2.0 mg/100 ml. However, chi 2 analysis demonstrated significant association between delta-ALA of this group to some of the variables. The strongest association was found in the habit of biting fingernails (P < 0.025). Other statistically significant correlations were found between delta-ALA and father's occupation (P < 0.05) and the amount of time spent playing in the field (P < 0.01). Generally, this study indicates that school children in Kajang and Sepang are still relatively safe from excessively high lead exposure. However, a more sensitive indicator, which is based on a lower tolerable lead limits, such as lead in blood, are necessary to affirm this finding.

Antral nodularity, gastric lymphoid hyperplasia, and Helicobacter pylori in adults

Our objective is to evaluate endoscopically-diagnosed antral nodularity in adults and its relationship to lymphoid hyperplasia (LH) and Helicobacter pylori (HP). Antral biopsy specimens were studied for inflammation, presence of HP, and lymphoid follicles. Patients with marked functional dyspepsia or recurrent duodenal ulcers were given triple therapy (bismuth subcitrate, tetracycline, and metronidazole in the recommended doses for 2 weeks) to eradicate HP. Follow-up endoscopy and biopsies, at least 4 weeks after finishing treatment, were performed to assess eradication of HP and its effect on nodularity and LH. In all 25 patients (age range, 20-42 years) with antral nodularity, biopsy specimens were positive for HP. Twenty (80%) of subjects had lymphoid follicles; 13 of these 20 were given triple therapy. Eradication of HP was achieved in five cases (38%). Patients in whom HP was successfully eradicated showed improvement of their symptoms; antral nodularity subsided and there was marked regression of the lymphoid follicles. Antral nodularity with LH, reported to be unique to children, is not uncommon in adults and is induced by HP, eradication of which leads to regression of nodularity and LH in most cases. Low eradication rates achieved with metronidazole-based triply therapy is due, possibly, to primary resistance to metronidazole. Long-term follow-up of such patients is required to assess the evolution of these findings.

Some aspects of dental health in young adult Indian vegetarians. A pilot study

The effect of a vegetarian diet on oral health status could be manifold, but reports have so far mainly appeared from within Western populations. This study reports the oral health status of southeast Indian vegetarians, obtained by means of a questionnaire, clinical examination, and study cast evaluations. The material comprised 30 vegetarians and 25 sex- and age-matched non-vegetarian controls. Comparison between the samples included dietary and oral hygiene habits, health-related variables, caries prevalence, and dentoalveolar characteristics. The questionnaire showed significantly less consumption of between-meal sweets and more widespread use of a soft toothbrush by the vegetarians. The vegetarians had a significantly higher degree of tooth wear than the non-vegetarians, but no difference in the degree of wear between women and men in either group was found. The vegetarians had a significantly higher tendency towards crowding in the maxillary arch, numerically higher DMFT, and greater number of cervical buccal defects than the controls. The results of this study suggest that the Indian vegetarian diet may produce certain effects on the oral health, associations that need to be studied further.

Maternal mortality rate in the Obstetric Unit of University Kebangsaan Malaysia: 1981-1990

This paper analyses maternal mortality as seen in the Obstetric Unit of the University Kebangsaan Malaysia. During the 10 year study period, the maternal mortality rate was 74/100,000 total births. Women who were non-booked, aged above 40 years, gradmultiparous and of India ethnicity were at the highest risk of maternal death. The commonest causes of death were hemorrhage, hypertension, embolism and sepsis. Post-mortem examinations were performed in only 8.2% of women who died.

Prevalence of occlusal tooth wear and its relationship to lateral and protrusive contact schemes in a young adult Indian population

The aim of the present study was to investigate the prevalence and severity of occlusal tooth wear and their interrelationships with lateral and protrusive occlusal contact schemes in a young adult Indian population. The material comprised 64 individuals (age: mean = 19 years; range, 17-24 years). Assessment of wear was performed by means of a tooth-by-tooth evaluation of casts. Lateral excursive and protrusive contact relationships were recorded at the clinical examination. There was no difference in the degree of wear between women and men. Mean occlusal wear was low for the population studied compared with similarly aged Scandinavians and Saudis. No differences in the severity of wear were found in relation to lateral excursive and protrusive contact schemes. Whereas the low wear experience in the present Indian sample may be related to dietary factors, more must be understood about the various other causes of occlusal tooth wear before its functional interdependence becomes clear.

Safety and effect of topical recombinant human interleukin-1beta in the management of pressure sores

Interleukin-1beta is produced by numerous cell types including monocytes and fibroblasts. It has been shown to stimulate multiple cell types including fibroblasts, keratinocytes, endothelial cells, neutrophils, macrophages, and lymphocytes. Previously, interleukin-1beta was shown to accelerate healing in partial-thickness and full-thickness wounds in animals and was also shown to be safe when applied topically in Phase I human trials. Therefore a prospectively randomized, blind, placebo-controlled trial was performed with patients with chronic pressure ulcers. Doses of interleukin-1beta of .01 microg, .10 microg, and 1.0 microg per square centimeter did not show acceleration of healing of the pressure ulcers. Therefore use of recombinant human interleukin-1beta in this study was safe but, at the dose levels tested, did not result in improvement in the healing ratio.

Visible scars and self-esteem in pediatric patients with burns

The supposition of often made that visible scarring is more psychologically damaging than are "hidden" burn scars, but little evidence exists to support that idea. We compared the self-evaluations of 28 male and 21 female pediatric patients with burns to the amount and visibility of scars. Males were 6 to 18 years old at the time of burn and sustained 15% to 99% total body surface area burns. They were evaluated 1 to 6 years after their burn injury. Females constituted a similar group. They were 5 to 18 years old at the time of burn, sustained 15% to 94% total body surface area burns, and were evaluated 1 to 7 years after their burn injury. All of the children underwent evaluation with the Piers-Harris Children's Concept Scale, evaluating themselves on intellectual and school status, physical appearance, anxiety, happiness and satisfaction, and behavior and popularity. Scores from these parameters were compared against each child's "visible" scars as seen on the face, head, neck, and hands. Also, comparisons were made with the numbers of reconstructive needs in these areas. Significant inverse correlations were found in the males. As the number of scars increased in these areas, the patient's scores for "physical appearance" and "happiness and satisfaction" decreased (p < 0.001). Other psychologic parameters were not affected. There was no effect by age of patient, and no significant correlations were found for the female group. The results emphasize the importance of the burn team's awareness that pediatric survivors of burns may appear superficially to be adjusting well, while harboring grave self-deprecating feelings. Those with "visible" scars will need special support to enhance self-esteem.

Effects of rat interleukin-2 and rat interferon on the natural killer cell activity of rat spleen cells after thermal injury

The natural killer cell activity of splenocytes from rats with scald injury was observed to be significantly suppressed at 7 days after injury compared with that of normal nonburned controls. Incubation of splenocytes from normal rats or rats with burn injury with either rat interleukin-2 or rat interferon (IFN-alpha and IFN-beta) significantly increased the natural killer cell activity. Addition of a rabbit anti-rat interferon antibody to spleen cells incubated with interleukin-2 did not produce any significant alteration in interleukin-2-related enhancement of natural killer cell activity. These results suggest that enhancement of natural killer cell activity after incubation of splenocytes with interleukin-2 is not due to interferon production but is an independent event. Preincubation of spleen cells with a mouse monoclonal antibody to rat interleukin-2 receptor was observed to abolish the interleukin-2-related enhancement of natural killer cell activity completely, whereas it partially blocked the interferon-related enhancement. These results were also confirmed by enhancement of natural killer cell activity of burned rats after in vivo administration of interleukin-2. Our studies thus indicate that after thermal injury, the observed decrease of natural killer cell activity can be enhanced by both interleukin-2 and interferon independently of each other. The decreased natural killer cell activity may be due to a decrease in interleukin-2 production or availability and not to an interleukin-2 receptor defect. These studies thus point toward a potential therapeutic significance of interleukin-2 in enhancing immune function after thermal injury.

Mantoux reaction survey conducted in the northern region of Saudi Arabia

A nationwide epidemiological survey is under way to assess the prevalence of tuberculosis infection in the inhabitants of Saudi Arabia. The assessment tools include the Mantoux test and culturing of sputum samples obtained from inhabitants of the five regions of the Kingdom. The study population has been selected using a proportional-to-population-size method with cluster sampling and urban/rural stratification. We report the results of the Mantoux test for the Northern Region, where 1340 subjects were screened. Only 4% of the non BCG-vaccinated children had a positive reaction (tuberculosis index = TI) which identifies the region as a middle prevalence country (2-14%), and indicates the need for better detection and treatment of open cases of tuberculosis in the community. The TI rose steeply with age to 58% in the 65+-year age group, which denotes the existence of a large pool of infected but healthy subjects who are liable to suffer active disease. The TI was higher males and in those doing manual work, but was not statistically influenced by nationality (Saudis versun non-Saudis), place of residence, or level of education. Our findings support the view that a positive tuberculin reaction in a child aged 5 to 14 years who has been vaccinated with bacillus Calmette-Guerin (BCG) should be attributed to infection with Mycobacterium tuberculosis and not BCG. This conclusion is based on our finding that only 5% of the children int he group of vaccinated subjects has a positive Mantoux reaction, 5% had an intermediate reaction (5 to 9 mm induration), and 90% had a negative reaction (0 to 4 mm induration).

Stimulation of human dermal fibroblasts with interleukin 2

The role of soluble inflammatory mediators in the wound healing process is under investigation. Interleukin 2 (IL2), an immune modulator produced by T lymphocytes, was tested in vitro for its effects on human diploid fibroblasts. Human diploid fibroblasts (1.0 x 10(4)) were incubated for 24 hours in Alpha minimal essential media (Gibco Laboratories, Gaithersburg, Md.) at 37 degrees C in 5% CO2 in air with 500 U/ml of IL2 (Cetus Corp., Emeryville, Calif.). Cells were then pulsed with 3 mu Ci/ml of tritiated thymidine overnight. The mean increase in the incorporation of tritiated thymidine of the cells treated with IL2 over control cells was 38% (p value less than 0.05). Interleukin 2 has a significant effect on the metabolism of human dermal fibroblasts and may accelerate the wound healing process.

The effect of insulin-like growth factor I on postburn hypermetabolism

These studies were undertaken to examine the effects of insulin-like growth factor I (IGF-I) on the hypermetabolic state that follows major thermal injury. Male Sprague-Dawley rats weighing 275 to 325 gm were subjected to a 50% total body surface area, full-thickness scald burn. At the time of injury, osmotic pumps were surgically implanted and used to deliver IGF-I, 1000 micrograms/day, or an equivalent volume of placebo solution by constant infusion of 5 microliters/hr for 14 days. Metabolic rates were studied with oxygen-consumption measurements performed on days 3, 7, 10, and 14 after injury. Animal weight measurements were also performed at the above intervals, with serum total IFG-I levels measured at death. Total serum IGF-I levels were decreased significantly 14 days after injury compared with uninjured animals (p less than 0.05). Treatment with IGF-I resulted in a significant decrease in oxygen consumption and a significant increase in body weight compared with burned animals and those treated with placebo 10 and 14 days after injury (p less than 0.05). These data suggest that IGF-I causes a significant change in the metabolic response that follows severe thermal injury and point to a possible role for IGF-I in the treatment of patients after severe thermal injury.

A case of Behcet's disease with intestinal involvement due to Crohn's disease

A 15-yr-old, Arabic male presented with painful, recurrent, self-resolving oral and genital ulcers, erythema nodosum and uveitis. Behcet's disease was diagnosed. A few months later, he experienced anorexia, abdominal pain, diarrhea, and weight loss. Although all routine laboratory and radiologic investigations were negative, colonoscopy revealed the presence of serpiginous ulcers with pseudopolyps and inflamed intervening mucosa in the proximal half of the colon. Therapy with oral steroids was helpful, but the disease exacerbated a few months after prednisone was discontinued. Repeat evaluation showed similar endoscopic findings and, on colonic biopsy, noncaseating granulomas compatible with Crohn's disease were seen. Again, the patient responded well to oral steroids and sulfasalazine. We believe that gastrointestinal involvement in our patient is compatible with Crohn's disease and that screening tests to rule out chronic inflammatory bowel disease should be performed in the presence of gastrointestinal involvement in Behcet's disease. Behcet's disease may be a part of the spectrum of chronic inflammatory bowel disease.

Importance of the hour of sampling in the lymphoblastic transformation assay of sheep peripheral blood lymphocytes

This paper describes the effect of the nycthemeral cycle on the lymphocyte response of sheep to different mitogens (PHA, Con A and PWM). A considerable decline in the lymphocyte response was evident in the afternoon and early in the morning in all 6 animals tested. Three peak responses were identified during a 24 hour study period, at 14.00 h, 24.00 h and 08.00 h. The results presented here suggest that this variation in lymphocyte response is a meaningful difference in the response ability of individual lymphocytes. Factors affecting the number of leukocytes and the proportion of different types of lymphocytes in peripheral blood might be the essential causes of variation. To obtain an accurate indication of an individual's immunocompetence, it is important to make a preliminary determination of the optimal hour for sampling. If this is not possible, all the samples must be taken at the same hour on each test day, in order to make significant comparisons.

Blastogenic response of peripheral blood lymphocytes from multiparous pregnant ewes

The immunocompetence of pregnant multiparous ewes was investigated with respect to the blastogenic response of peripheral blood lymphocytes of (PBL) to three mitogens: PHA, Con A, and PWM. The profile of PBL responses shows 1) progressive suppression at 36 and 66 days of gestation, 2) enhanced response at 97 days of gestation, which approaches the mean values observed at the premating period, and 3) a redecline of the response at 137 days of gestation to depressed values lower than observed at 36 and 66 days of gestation. The results suggest that mitogen-treated lymphocytes were depressed and that the immunodepressive factor(s), which can influence lymphocytes at the systemic level, may be involved in the maintenance of the ovine fetal semiallograft.

Lymphoblastic transformation assay of sheep peripheral blood lymphocytes: a new rapid and easy-to-read technique

A new micro-method was used to evaluate in vitro sensitivity of ovine peripheral blood lymphocytes (PBL) to different non specific mitogens (pHA, Con A, PWM) and to investigate the interest of a colorimetric assay for measurement of transformed lymphocytes. The results showed that sheep PBL in flat-bottomed microplates responded optimally at a cell density of 8 X 10(6) cells/ml to PHA (2.5 micrograms/ml), Con A (5 micrograms/ml) and PWM (5 micrograms/ml). The colorimetric assay using a tetrazolium salt (MTT), for measuring the transformed lymphocytes, is very well correlated with the classical method of [3H]thymidine incorporation. This new revelation technique of the mitogenic response improve the technical value of the assay, which is more rapid and easy-to-read, without diminishing the biological value.