Accumulation of the endogenous L-arginine analogue NG-monomethyl-L-arginine in human end-stage renal failure patients on regular haemodialysis

We measured plasma levels of L-arginine, its analogue NG-monomethyl-L-arginine (L-NMMA), and related amino acids in normal subjects and uraemic patients (n = 31), before and after haemodialysis. Plasma levels of L-arginine were reduced to less than half of normal values in uraemic subjects compared with controls, and were not affected by haemodialysis. L-NMMA was not detectable in non-uraemic subjects, but markedly elevated in uraemic patients. In parallel, we used human red blood cells as a model to study the effect of L-NMMA upon the transport of L-arginine. L-NMMA trans-stimulated L-arginine transport significantly, confirming that L-arginine and L-NMMA share common transport pathways. Our results suggest altered L-arginine metabolism and the presence of an increased concentration of a NO synthase inhibitor in uraemia. We propose that alterations in plasma L-arginine levels and increased production of L-arginine analogues will alter NO synthesis and may help to explain some pathological changes seen in uraemia.

Nitric oxide kinetics during hypoxia in proximal tubules: effects of acidosis and glycine

In the present study, we directly monitored nitric oxide (NO) with an amperometric NO-sensor in suspensions of rat proximal tubules. Hypoxia-stimulated NO generation was characterized by an initial rise and a subsequent sustained increase which preceded cell membrane damage as assessed by lactic dehydrogenase (LDH) release. In contrast, the NO concentration remained unmeasurable in normoxic controls. Nitro-L-arginine-methyl ester (L-NAME) prevented the hypoxia-induced increase in NO in a dose dependent manner in parallel with incremental cytoprotection. The hypoxia-induced elevation in NO and the associated membrane injury were both markedly prevented by extracellular acidosis (pH 6.95). In vitro proximal tubular nitric oxide synthase (NOS) activity (3H-arginine to 3H-citrulline assay) was pH dependent with optimum activity at pH 8.0 and greatly reduced activity at acidic pH even in the presence of calcium and co-factors. However, glycine, a well recognized cytoprotective agent, did not attenuate the NO concentration during hypoxia. The present study therefore provides direct evidence that NO is generated by rat proximal tubules during hypoxia and demonstrates that the protective effect of low pH against hypoxic rat tubular injury is associated with an inhibition of this NO production.

Retention of an albumin-bound furan dicarboxylic acid in patients with chronic renal failure or after a kidney transplant

BACKGROUND

3-Carboxy-4-methyl-5-propyl-2-furanpropanoic acid (5-propyl FPA) is a furan dicarboxylic acid which accumulates in the plasma of patients with renal impairment. 5-Propyl FPA is an inhibitor of the binding of drugs to albumin and is also implicated in other aspects of the uraemic syndrome.

METHODS

Plasma concentrations of propyl FPA have been measured in non-dialysis-dependent, chronic renal failure patients and in renal transplant patients by high-performance liquid chromatography. Concentrations of haemoglobin, albumin and creatinine were also determined.

RESULTS

There was a positive correlation between serum creatinine and 5-propyl FPA and a negative correlation between haemoglobin concentration and 5-propyl FPA in chronic renal failure patients. There was a negative correlation between 5-propyl FPA and duration of transplant only when the serum creatinine was >200 microM. The mean plasma concentration of 5-propyl FPA in chronic renal failure patients with plasma creatinine

CONCLUSIONS

This retention of 5-propyl FPA may therefore reflect a specific tubular defect in renal transplant patients treated with cyclosporin and points to the possibility that 5-propyl FPA may serve as a marker of tubular dysfunction.

Monitoring of endothelial leucocyte adhesion molecule-1 in anti-neutrophil-cytoplasmic-antibody-positive vasculitis

Soluble endothelial leucocyte adhesion molecule-1 (ELAM-1) has been shown to act as a neutrophil chemoattractant and may also represent a specific marker of endothelial cell damage or activation. Nine patients with anti-neutrophil cytoplasmic antibody (ANCA)-positive vasculitis (p-ANCA: n = 4, c-ANCA: n = 5) were prospectively monitored for disease activity by serial serum ELAM-1, C-reactive proteins (CRPs), von Willebrand factor (vWF) and ANCA levels. Six patients presented acutely with biopsy-proven renal vasculitis. One patient on dialysis, one in remission with stable renal function and one renal transplant patient developed clinical and serological relapse. Seven patients had abnormally high ELAM-1 (>60 ng/ml) levels at presentation. These fell within normal limits a week following pulse methyl prednisolone therapy. This preceded a fall in CRP, vWF and subsequent clinical remission. p-ANCA serology remained positive in 3 cases. One patient relapsed with rising ELAM-1 levels. Two patients developed erroneously positive ANCA serology but serum ELAM-1 remained normal. Six patients with chronic renal impairment of non-vasculitic origin who presented acutely with septicaemia had normal serum ELAM-1 levels (mean +/- SD: 31 +/- 10 ng/ml) at presentation and during the subsequent clinical course. These preliminary findings are encouraging, especially when ELAM-1 is combined with ANCA monitoring in vasculitis. However, further data from larger controlled studies are needed to validate the utility of ELAM-1 in the monitoring of patients with vasculitis.

Carbohydrate analysis of the B2 bradykinin receptor from rat uterus

The B2 bradykinin receptor purified from rat uterus has an apparent molecular mass of 81 kDa. This is higher than the value of 42 kDa estimated from the sequence data of rat and human B2 receptors. Carbohydrate analysis of the rat B2 bradykinin receptor indicated that it was a sialoglycoprotein with three N-linked complex oligosaccharide side chains. This was consistent with the sequence, which has three potential glycosylation sites. The receptor did not appear to possess O-linked carbohydrate side chains. Removal of the N-linked carbohydrates with endo-beta-N-acetylglucosaminidase yielded a core protein of 42-44 kDa. The presence of these N-linked carbohydrates explains the discrepancy between the molecular size of the purified receptor protein and that estimated from the sequence. The sequence of the rat receptor suggests an isoelectric point of about pH 7.0, but the purified receptor had an isoelectric point of pH 4.5-4.7. Sialic acid residues on the N-linked side chains are likely to be responsible for the acidic nature of the rat receptor. Carbohydrate does not appear to play a role in ligand-receptor interactions, as deglycosylation did not alter the affinity of the B2 bradykinin receptor for bradykinin or the B2-selective antagonist HOE-140.

Severe mental retardation in 2 to 24-month-old children in Lahore, Pakistan: a prospective cohort study

Severe mental retardation (developmental quotient (DQ) < 50) was investigated in 1303 children from 2 to 24 months of age, born during 1984-87 in four population groups representing different socio-economic levels in and around Lahore, Pakistan. The incidence per 1000 live births was 22 in the periurban slum, 9 in the urban slum, 7 in the village and 4 in the upper middle class group. The aetiology was prenatal in 79%, perinatal in 14% and untraceable in 7% of cases. Down's syndrome was the most common cause of severe mental retardation (36%). Impairments were studied at 2 years of age. Impairment of language was present in all, while locomotor dysfunction was seen in 89% of cases. Epilepsy and cerebral palsy were each present in 22% of cases. Mortality among these severely mentally retarded children was 36%.

Case report: the diagnostic value of contrast-enhanced computed tomography in acute bilateral renal cortical necrosis

Acute bilateral renal cortical necrosis is a relatively rare cause of acute renal failure accounting for only 2% of cases in the Western World. The pathophysiology of this condition is complex, but ultimately leads to the destruction of the renal cortex with sparing of the renal medulla. A definitive diagnosis is based on renal histology. In this report we describe a patient in whom this diagnosis was made using contrast-enhanced computed tomography as renal biopsy was contraindicated.

Biochemical markers of basement membrane disturbances and occupational exposure to hydrocarbons and mixed solvents

To investigate possible mechanisms of hydrocarbon or solvent-induced renal damage, we studied three groups of healthy men employed in a UK manufacturing plant. Group 1 (n = 111) were occupationally exposed to hydrocarbon-based paints, Group 2 (n = 100) were occupationally exposed to petroleum-based mineral oils, and Group 3 (n = 92) had low background occupational exposure to hydrocarbons. Occupational atmospheric exposure levels for toluene, xylene, butanol and oil mist around the time of this study were within UK permissible limits. Group 4 (controls) were males with no known occupational hydrocarbon or solvent exposure (n = 108). Circulating laminin antibodies and the auto-antibody implicated in Goodpasture's syndrome (anti-GBM) were measured, as were serum laminin, a basement membrane turnover marker, and soluble E-selectin, an endothelial activation marker. Group 1 had a significantly greater proportion of subjects with high levels of both anti-laminin antibodies and soluble E-selectin; Group 2 had significantly more subjects with raised anti-GBM antibodies, laminin and soluble E-selectin. Mean levels of soluble E-selectin were increased in Groups 1 and 2. In a small but significant proportion of these workers exposed to hydrocarbons/mixed solvents there are alterations both to basement membranes, resulting in auto-antibody production, and to overlying vascular endothelial cells.

Tubular damage in microalbuminuric patients with primary glomerulonephritis and diabetic nephropathy

Tubular damage as suggested by enzymuria and tubular proteinuria is a recognized feature of glomerulonephritis (GN) with clinical proteinuria and both incipient and overt diabetic nephropathy (DN). However, little is known about the presence of tubulopathy in patients with primary GN, microalbuminuria [albumin excretion (AER) 30-300 mg/d] and microhematuria. Three groups were studied. The GN group comprised 17 (2 F) patients with biopsy-proven GN with microalbuminuria. The DN group comprised 35 (14 F) patients with incipient diabetic nephropathy with AER 30-300 mg/d, and controls comprised 38 (15 F) normal subjects with normal AER < 30 mg/d. Serum creatinine, albuminurinuria, transferrinuria, and markers of tubular damage such as urinary excretion of N-acetyl-glucosaminidase (NAG), leucine aminopeptidase (LAP), gamma-glutamyl transferase (gGT), and retinol binding protein (RBP) were measured. GN and DN had comparable degrees of albuminuria, transferrinuria, and LAP excretion, and these were significantly higher than controls. Serum creatinine was significantly higher in GN than DN and controls. DN had significantly higher NAG and RBP, and lower gGT than GN and controls. In both GN and DN groups, both glomerular proteins correlated with each other and NAG correlated significantly to LAP and gGT. Albuminuria correlated to tubular enzymuria in GN group but not in patients with DN. The results suggest that tubular damage is less marked in microalbuminuric patients with GN than those with DN despite similar degree of glomerular proteinuria. The pattern of tubulopathy is also different in the two groups, indicating differences in the pathogenesis of tubular damage in these two clinical settings.

Tubulopathy with macroalbuminuria due to diabetic nephropathy and primary glomerulonephritis

Tubular damage is a recognized feature of both overt diabetic nephropathy and glomerulonephritis. However, the pattern and mechanism of tubular damage in the two clinical settings remain unclear. Two groups of patients with macroalbuminuria (albuminuria > 300 mg/day) were studied. Group 1 comprised 41 patients with biopsy proven primary glomerulonephritis and group 2 comprised 28 patients with clinical diabetic nephropathy due to insulin dependent diabetes mellitus. Serum creatinine, creatinine clearance, glomerular proteinuria (albuminuria and transferrinuria), markers of tubular damage such as urinary excretion of lysosomal enzyme (N-acetyl glucosaminidase), brush border enzymes (leucine aminopeptidase and gamma-glutamyl transferase) and retinol binding protein (tubular protein) were measured. Both groups were comparable in serum creatinine, creatinine clearance, glomerular proteinuria and excretion of N-acetyl-glucosaminidase. However, a significantly higher degree of tubular brush border enzymuria and a lower level of tubular proteinuria were seen in group 1 than in group 2. In group 1, albuminuria correlated to tubular enzymuria and tubular proteinuria. However, there was no correlation in diabetic patients between parameters of glomerular and tubular damage or dysfunction. The data presented suggested that the pattern of tubulopathy is different in patients with comparable degree of macroalbuminuria due to diabetic nephropathy and glomerulonephritis. Moreover, in diabetic nephropathy contrary to glomerulonephritis, markers of tubular damage are unrelated to glomerular proteinuria. This may suggest different mechanisms of tubular damage in the two clinical settings. We recommended that in all patients with proteinuria, particularly those with diabetic nephropathy, markers of renal tubular damage may be useful in monitoring the course of their disease.

Evidence of oxidant injury and tubular damage in early diabetic nephropathy

Two groups of patients with insulin-dependent diabetes mellitus of > 10 years duration and either persistent normoalbuminuria (group 1, n = 49; albumin excretion < 30 mg/day) or microalbuminuria (group 2, n = 33; albumin excretion 30-300 mg/day) were investigated for evidence of free oxygen radical activity (erythrocytic superoxide dismutase and glutathione peroxidase) and oxidant injury (serum malondialdehyde). Glomerular proteinuria (albuminuria, transferrinuria), tubular proteinuria (retinol-binding protein) and tubular enzymuria (N-acetyl-glucosaminidase and leucine aminopeptidase) were also measured. Healthy controls (n = 38) were matched for age and sex. Groups 1 and 2 were similar in terms of age, sex, duration of diabetes and recent glycaemic control. Serum cholesterol and creatinine were similar in all three groups. Free-radical activity and oxidant injury were significantly higher in groups 1 and 2 than in controls (p < 0.001). Glomerular proteinuria, tubular proteinuria and enzymuria were significantly higher in group 2 than in group 1 and controls (p < 0.01). Group 1 had significantly higher transferrinuria, tubular enzymuria and tubular proteinuria than controls. However, groups 1 and 2 were similar in degree of free oxygen radical generation and oxidant injury. In diabetic nephropathy, oxidant injury and renal tubular damage accompany and may even precede microalbuminuria. The presence of these abnormalities in the absence of glomerular proteinuria favours the hypothesis that alterations first occur in the peritubular microcirculation, which by causing oxidant injury and tubular damage, may initiate diabetic nephropathy.

Occupational hydrocarbon exposure and diabetic nephropathy

Exposure to hydrocarbons has been implicated in the pathogenesis of glomerulonephritis but its role in the development of diabetic nephropathy remains unknown. Three groups of patients with Type 1 diabetes of over 10 years duration were studied. Group 1 comprised 45 patients (23 F) with no diabetic nephropathy (urinary albumin excretion (AER) < 30 mg 24 h-1), group 2 comprised 37 patients (17 F) with incipient diabetic nephropathy (AER between 30-300 mg 24 h-1), and group 3 comprised 31 patients (15 F) with overt diabetic nephropathy (AER > 300 mg 24 h-1). The groups were comparable for age, sex, duration of diabetes, recent glycaemic control, social class, and residential area. Patients were assessed blindly by a validated questionnaire and interview for hydrocarbon exposure, consumption of tobacco, analgesic agents, and alcohol. Exposure scores to hydrocarbons derived from the questionnaire were significantly higher in patients with incipient and overt diabetic nephropathy with smoking adjusted odds ratios of 3.6 and 5.2, respectively. The consumption of alcohol, analgesic agents, tobacco, and smoking habits were similar in the three groups. In conclusion, hydrocarbon exposure may be a key environmental factor in the development of diabetic nephropathy in patients with Type 1 diabetes.

Abdominal symptoms, hypercalcaemia and apathetic hyperthyroidism: treatment with pamidronate

A 24-year-old man with anorexia, repeated bouts of vomiting, and wasting was found to have florid thyrotoxicosis and hypercalcaemia. Pamidronate promptly reduced the serum calcium concentration to normal, and simultaneously abated the abdominal symptoms, which did not recur in spite of continuing severe hyperthyroidism, which was eventually controlled by radioactive iodine ablation of thyroid activity.

Purification and characterisation of B2 bradykinin receptor from rat uterus

A B2 bradykinin (BK) receptor was solubilised and partially purified from rat uterine membranes by a combination of ammonium sulphate precipitation, desalting on Sephadex G-50, and hydroxyapatite and wheat germ agglutinin affinity chromatography. The partially purified BK receptor, enriched 1,500-fold, was then cross-linked to 125I-Tyr0-BK using disuccinimidyl suberate and purified to homogeneity as a single protein species on two-dimensional gel electrophoresis with a molecular mass of 81 kDa. This molecular size was in agreement with the value of 80-120 kDa estimated from Sephacryl 300 size exclusion column chromatography of the B2 receptor. The partially purified and the crude solubilised B2 BK receptor from rat uterus showed similar affinities for BK and the BK analogues iodo-Tyr0-Bk, D-Phe7-BK, and des-Arg9-BK, indicating that the ligand binding specificity of the receptor had been retained during the purification procedures. The biochemical properties of the solubilised B2 BK receptor correspond to those of a hydrophobic acidic glycoprotein (isoelectric focusing gave a value of 4.5-4.7) that binds specifically to wheat germ agglutinin but has no affinity for either concanavalin A or lentil lectin, suggesting the absence of terminal mannose or glucose residues.

Occupational factors and renal disease

The male-to-female ratio of patients requiring dialysis treatment commonly approaches 2:1. It is proposed that environmental factors, particularly occupational exposure to hydrocarbons, may account for the excess number of male patients. The term "hydrocarbon" refers to the aliphatic, alicyclic, aromatic, and halogenated hydrocarbons (carbon tetrachloride, chloroform); glycols (ethylene glycol, diethylene glycol, dioxane, glycerol); and organic solvents. Hydrocarbons commonly find use as solvents in industrial manufacturing practices because of their lipid solubility. Hydrocarbons have long been known to be neurotoxicants, affecting both peripheral and central nervous systems. Although benzene and its derivative have a known association with uroepithelial tumors, there is now a considerable body of evidence suggesting a possible role for hydrocarbon exposure in the development of non-neoplastic renal diseases. This article presents an epidemiological case for such an association and critically reviews the literature.

Relationship between markers of endothelial dysfunction, oxidant injury and tubular damage in patients with insulin-dependent diabetes mellitus

1. Diabetic nephropathy is a serious microvascular complication in patients with insulin-dependent diabetes mellitus, resulting in end-stage renal disease in 30-45% of such patients. Despite intensive investigation, the pathophysiology of diabetic renal disease has not been fully elucidated. However, several clinical and experimental studies have suggested that endothelial dysfunction and free-radical activity may be important factors. 2. Forty normotensive patients with insulin-dependent diabetes mellitus of between 10 and 20 years duration with persistent normoalbuminuria (albumin excretion < 30 mg/day) and normal renal function were investigated for markers of endothelial dysfunction (plasma von Willebrand factor, soluble thrombomodulin and angiotensin-converting enzyme activity), free oxygen radical generation (erythrocytic superoxide dismutase and glutathione peroxidase) and oxidant injury (serum malondialdehyde). Glomerular proteinuria (albuminuria, transferrinuria), tubular proteinuria (retinol-binding protein) and tubular enzymuria (N-acetyl glucosaminidase and leucine aminopeptidase) were also measured. 3. Patients were divided into two groups. Group 1 comprised 21 patients with elevated markers of endothelial dysfunction, and group 2 comprised 19 patients with normal levels of plasma von Willebrand factor, soluble thrombomodulin and angiotensin-converting enzyme activity. Thirty-eight healthy subjects matched for age and sex acted as controls. 4. Groups 1 and 2 were similar in age, sex, body weight, duration of diabetes mellitus and recent glycaemic control. Serum cholesterol, serum creatinine and glomerular proteinuria were similar in the three groups. Group 1 patients had significantly increased oxidant injury, tubular enzymuria and proteinuria compared with group 2 patients and control subjects (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Hydrocarbon exposure and tubular damage: additional factors in the progression of renal failure in primary glomerulonephritis

To investigate the role of hydrocarbon exposure in the progression of glomerulonephritis, 68 patients (12 female) with biopsy-proven primary glomerulonephritis (60 proliferative cases, 8 membranous) were blindly assessed for chronic hydrocarbon exposure by a validated questionnaire. Serum creatinine, proteinuria, and urinary excretion of markers of renal tubular damage were measured. Patients were assessed for evidence of progressive renal failure (PRF) (defined as persistent rise of serum creatinine > 50 mumol/l above the baseline) during a mean follow up period of 5 years. Patients were divided according to the presence or absence of PRF, (group 1, n = 29, with PRF) and (group 2, n = 39, without PRF). The two groups were comparable in age, sex, duration of diagnosis (since the time of biopsy) and blood pressure control. The derived chronic hydrocarbon exposure scores were significantly higher in group 1 than 2 (p < 0.001). Moreover, hydrocarbon exposure score since the diagnosis of glomerulonephritis was significantly higher in group 1 than 2 (p < 0.001). In group 1, 73% of patients continued to be exposed to hydrocarbons at their work site after the diagnosis of glomerulonephritis, compared to only 13% in group 2 (p < 0.001). At renal biopsy, group 1 had a significantly higher mean serum creatinine than group 2 but the degree of proteinuria and proportion of patients with hypertension were similar. During follow-up serum creatinine rose significantly in group 1 but not in group 2. In group 2, proteinuria fell significantly during follow-up but remained unchanged in group 1. A higher proportion of patients from group 1 developed hypertension requiring antihypertensive drugs (84% vs. 28%; p < 0.001). Urinary marker secretion data indicated a possible association between tubular damage and renal impairment. These results suggest that chronic hydrocarbon exposure and renal tubular damage are important additional risk factors in the progression of primary glomerulonephritis.

Early child health in Lahore, Pakistan: XII. Milestones

Psychomotor development was assessed in 1476 infants from four different levels of urbanization in and around Lahore, Pakistan. Development was assessed monthly at birth to 24 months of age by using a set of 10 milestones selected from the Denver Developmental Screening Test and the Developmental Screening Inventory. The psychomotor development of children in the upper middle (Um) class was consistent with reference population groups in Europe and North America, hence this group was used as control. There was significant delay in the psychomotor development of infants belonging to the poorer areas compared to the Um class. There was no sex difference in the development of the milestones in any study area, except for girls in the Um class who were earlier for about one month than boys in talking. Infants in the poorer areas were, on average about 3 months, delayed in their walking and fine motor activity (building a tower of 3 cubes) in comparison with the Um class. Observed disturbance in psychomotor development at an early age may affect the abilities and achievements in later life.

Early child health in Lahore, Pakistan: II. Inbreeding

The prevalence of consanguineous marriages was studied in 940 families belonging to four different socio-economic groups in and around Lahore, Pakistan. The births occurring in these families from September 1984 to March 1987 were also investigated for birth defects. The overall prevalence of consanguineous marriages was 46%. The first cousin marriages were most common (67%), followed by the marriages between second cousins, 19%. The prevalence of consanguineous marriages was clearly associated with the socio-economic status of the study groups; 50% of the marriages was related in the periurban slum, 49% in the village, 44% in the urban slum and 31% in the upper middle class. The birth defects were also more prevalent in the poorer areas, being highest in the periurban slum (17.7%) followed by the urban slum (15.6%) and then the village (14.8%) and lowest in the upper middle class (12.3%). Although, the frequency of both consanguinity and birth defects were related with the socio-economic levels of the study groups, there was no association between inbreeding and birth defects. Perhaps, deleterious recessive genes for birth defects have been "bred out", because of continuous inbreeding over generations in this population. There was a significant predilection of major birth defects in boys without clear sex linkage. The conclusion is that the rate of consanguineous marriages was high, especially in the poorer areas, but the relationship between consanguineous marriages and birth defects was little or none. However, other child health indicators may be affected by consanguineous marriages.

Early child health in Lahore, Pakistan: IX. Perinatal events

In Pakistan there are a number of acute problems related to maternal and infant health in the perinatal period. There is also lack of reliable data needed for the formulation of action strategies. To provide a database 1490 women have been followed from the 5th month of pregnancy in four different areas at various levels of urbanization and socio-economic development. After adjusting for gestational age, the proportion of newborns with weight for length < -2SDS in relation to the Swedish National Standard was 12-31% for boys and 12-25% for girls, the figure being highest in the most deprived area. Preterm birth was infrequent compared with IUGR. The overall prevalence rate of birth defects was 21% out of which 8% were severe defects. The overall perinatal mortality rate was 56/1000 births, with rates of 60, 75, 36 and 33/1000 births for the village, periurban slum, urban slum and the upper middle class. Two thirds of the deaths were related to either a continuation of intrauterine disturbances or severe congenital defects incompatible with life. One third of the deaths were due to infection; mostly diarrhoea, clinical sepsis and ARI. Neonatal mortality was significantly related to birth length (< -2SDS, odds ratio 5.5) and length of gestation (< 37 weeks, odds ratio 5.6) and was to a lesser extent related to weight (< -2SDS, odds ratio 2.0) and weight for length (< -2SDS, odds ratio 1.3). Forty percent of the mothers had weight for height below -2SDS, 23-35% had height < -2SDS. Forty percent of mothers from a subset within the cohort had a hemoglobin < 10 gm/dl and 20% showed signs of pre-eclampsia. This presentation raises the issue of expanding the current Child Survival Programs into the perinatal period as well.

Early child health in Lahore, Pakistan: XI. Growth

This work gives growth reference values at birth to 24 months of age for Pakistan based on upper middle class infants. Growth rate reference values are also included and they are given for various interval lengths. The growth was differently affected in infants living in three poorer areas; the stunting incidence at 24 months of age was 63% in periurban slum, 54% in the village and 26% in the urban slum. Less differences could be seen between the areas in weight for length. There was an age dependency in the incidence of reduced growth; a normal length gain was seen at birth to about six months of age, but they were highly reduced at 6 to 18 months of age. The weight gain was to some degree reduced during the first 12 months of life, followed by a catch-up growth period. The seasonal influence was also age dependent; weight was highly affected during the summer at birth to 24 months of age, but not in the winter. The seasonal effect in length was marginal at birth to 6 months, little at 6 to 12 months (although, constant below the normal) and large at 12 to 24 months of age. We did not see any seasonality of growth in the reference group. The incidence of reduced growth reflects the socio-economic differences in one restricted geographic area, i.e., in the city of Lahore, Pakistan.

Renal impairment with chronic hydrocarbon exposure

Occupational hydrocarbon exposure is believed by some investigators to play an important role in the development of several non-neoplastic renal diseases. In view of the continuing debate in this area of nephrology we adopted a cross-sectional approach by investigating the prevalence of clinical or sub-clinical renal dysfunction in subjects chronically exposed to hydrocarbons at their work site. Three groups of healthy men working in different and separate areas of a major car manufacturing plant in the North-west of England participated in the study. Group 1 comprised 112 paint sprayers with exposure to paint-based hydrocarbons, group 2 comprised 101 volunteers working in the transmission area of the plant with exposure to petroleum-based mineral oils, and group 3 comprised 92 automated press operators with minimal background exposure to lubricants who acted as internal controls. Early markers of renal dysfunction such as serum creatinine, urinary total protein, albumin, transferrin, retinol binding protein, N-acetyl-glucosaminidase, gamma-glutamyl transferase, and leucine-amino-peptidase excretion were measured. Upper reference values of the parameters measured were derived from 105 comparable laboratory based controls with no occupational exposure to hydrocarbons or heavy metals. Group 1 had a significantly higher prevalence of elevated serum creatinine than the other groups and a higher prevalence of abnormal urinary total protein, N-acetyl-glucosaminidase, gamma-glutamyl transferase, and leucine-amino-peptidase excretion than groups 2 and 3. Group 2 had normal serum creatinine but a significantly higher prevalence of abnormal urinary total protein, transferrin, retinol binding protein, N-acetyl-glucosaminidase, and leucine-amino-peptidase excretion than group 3. Serum albumin was similar in all groups. There was some clustering of abnormal findings but the markers of renal dysfunction used in the study identified 37 individuals in group 1 and 31 subjects in group 2 with at least one abnormal parameter, compared to only five individuals in internal controls. This difference between the two target groups and group 3 was highly significant (p < 0.001). Subjects with chronic paint exposure had renal impairment and tubular dysfunction. Tubular dysfunction was also prominent with petroleum oil exposure. We therefore conclude that chronic hydrocarbon exposure may be associated with clinical and sub-clinical renal dysfunction. We advocate careful monitoring of workers exposure to hydrocarbons and for more effective preventive measures.

Resistance to recombinant human erythropoietin due to aluminium overload and its reversal by low dose desferrioxamine therapy

Seventeen severely anaemic and transfusion-dependent haemodialysis patients with a haemoglobin less than 7 g/dl were treated with recombinant human erythropoietin (r-Hu-EPO). Aluminium toxicity was diagnosed by a positive desferrioxamine (DFO) test and bone biopsy. Seven out of eight patients without aluminium toxicity responded to r-Hu-EPO therapy. Similarly all patients with aluminium toxicity (n = 4) but pre-treated with standard dose of DFO prior to r-Hu-EPO therapy responded but none of the patients with untreated aluminium toxicity (n = 5) responded to r-Hu-EPO therapy. In order to achieve adequate response in these patients, r-Hu-EPO and DFO had to be given in combination. The dose of desferrioxamine used to reverse r-Hu-EPO resistance was less and also used for a short time. We therefore confirm r-Hu-EPO resistance owing to aluminium overload and report its successful and safe reversal with low dose DFO therapy.

Urinary dopamine excretion in chronic renal disease

We have measured unconjugated urinary dopamine and investigated its relationship to glomerular filtration rate in two groups of 22 patients with chronic renal failure matched for age and sex, one group with primary glomerular disease, the other with tubulo-interstitial disease. Urine dopamine excretion was similar in both glomerular and tubulo-interstitial disease groups, and correlated significantly with creatinine clearance. Although urinary protein excretion was significantly higher in glomerular disease, urinary sodium excretion, fractional sodium excretion, urine flow rate and free water clearance were similar in both groups and did not correlate with dopamine excretion. These results suggest that in patients with chronic renal disease, urinary dopamine excretion is mainly under the influence of the glomerular filtration rate, irrespective of the underlying pathology, and therefore interpretation of urinary dopamine excretion requires a knowledge of the patients' renal function.

Prevention of bacterial infection and sepsis in acute severe pancreatitis

Between 1984 and 1986 six patients with acute respiratory failure (requiring ventilation for at least 3 days) complicating acute pancreatitis were managed on the intensive care unit (median ventilation period 6 days; range 3-41 days). Between 1987 and 1989 nine similar patients were managed (median ventilation period 35 days, range 4-69 days), and a regimen of enteral tobramycin, polymyxin and amphotericin to selectively decontaminate the digestive tract (SDD) was introduced. Five of six patients treated before 1987 had serious infections (three Gram-negative, one fungal), compared with only one of nine patients treated with SDD (P < 0.05). Clinical signs of sepsis were evident for 62% of the pre-SDD period, compared with 39% of the period during SDD therapy (P < 0.001). Systemic antibiotic prescribing was reduced in the SDD group; however, mortality remained unaffected with only two patients surviving pre-SDD and three during SDD treatment. SDD reduces infection rates and sepsis in patients with acute pancreatitis and may help to improve the prognosis of this life-threatening condition.

Primary glomerulonephritis and hydrocarbon exposure: a case-control study and literature review

A case-control study was undertaken to investigate the possible role of chronic hydrocarbon exposure and tobacco and alcohol consumption in the causation of primary glomerulonephritis. Exposure to hydrocarbons and the consumption of tobacco and alcohol were assessed blindly by telephone interview and questionnaire in 55 patients with end-stage renal disease due to biopsy-proven primary glomerulonephritis in whom there had been no evidence of systemic disease. This was compared with 55 normal subjects matched for age, sex, social class and residential area and a comparable internal control group of 45 patients with end-stage renal disease secondary to systemic disease, diabetic nephropathy or chronic pyelonephritis. Hydrocarbon exposure scores derived from the results of the questionnaires were significantly higher (p < 0.001) in the patients with primary glomerulonephritis than in the normal subjects and the internal control group. Moreover, more detailed assessment of the type of hydrocarbon exposure showed significantly greater exposure of patients with glomerulonephritis to petroleum products (p < 0.001), greasing/degreasing agents (p < 0.01) and paints/glue (p < 0.05), and a resulting estimated relative risk of developing glomerulonephritis with each type of hydrocarbon exposure of 15.5, 5.3 and 2.0. Those patients with heavy hydrocarbon exposure (hydrocarbon score > 25,000) had a significantly higher serum creatinine at presentation than those with mild to moderate exposure, suggestive of more advanced renal disease. However, there was no significant difference in tobacco and alcohol consumption among subjects in different groups. We conclude that occupational exposure to hydrocarbon is likely to play a role in the pathogenesis of primary glomerulonephritis and that the risk of developing glomerulonephritis is greatest in those subjects exposed to petroleum products.

Suppression of the renin-angiotensin-aldosterone axis with erythropoietin therapy by a negative feedback loop

To investigate the pathophysiology of hypertension in patients receiving recombinant human erythropoietin (rHuEpo) we studied its effects on the renin-aldosterone axis of chronic haemodialysis (HD) patients not receiving antihypertensive drugs. Nine severely anaemic normotensive HD patients received rHuEpo 50 U/kg bodyweight, thrice weekly after each HD. The dose was increased by 25 U/kg bodyweight every 4 weeks to a maximum of 100 U/kg or until an increase of Hb or Hct of 2 g/dl or 7% was achieved. Blood samples were taken after 30 min supine rest and while seated 10 min later after gentle ambulation. Results expressed as mean +/- SEM: therapy in normotensive HD patients by a negative feedback loop, before the development of hypertension.

Light chain nephropathy. Case report

Two patients with light chain nephropathy are described. The diagnosis and management of this rare condition is discussed.

Phlebotomy for erythropoietin-induced malignant hypertension

Four patients on regular dialysis treatment whose blood pressure was well controlled, developed malignant hypertension while receiving maintenance recombinant human erythropoietin (r-Hu-EPO). None of these patients had a haematocrit greater than 35% at any stage, and clinically, none had any evidence of fluid overload. Initially, they were all managed by stopping r-Hu-EPO and intensification of antihypertensive therapy. However, none of the patients responded, and venesection of 500 ml of blood was performed in each case with swift and sustained response.

Haemodialysis-related porphyria cutanea tarda and treatment by recombinant human erythropoietin

Haemodialysis-related porphyria cutanea tarda is a rare, but serious and mutilating skin condition, resulting from extremely high plasma porphyrin levels because of their inadequate clearance by haemodialysis. The treatment is very difficult as chloroquine is ineffective and venesection, the conventional treatment of this disease, is not always an option because of anaemia of end-stage renal disease. We report a case of haemodialysis-related porphyria cutanea tarda and her successful management by recombinant human erythropoietin treatment.

Bladder tumours in paraplegic patients on renal replacement therapy

Fourteen adult patients with end-stage renal disease due to spina bifida or spinal-cord injury underwent regular haemodialysis for 3-120 (mean 20) months. Seven of these patients received renal transplants. Urinary bladder tumours developed in four of the fourteen patients (three squamous-cell carcinoma in patients stil on dialysis, one poorly differentiated transitional-cell carcinoma in a patient after successful transplantation). All four had widespread metastatic disease and died within 8 weeks of the diagnosis of cancer. We recommend regular urological evaluation for patients with neurogenic bladder even after initiation of dialysis treatment. Total cystectomy before transplantation might greatly reduce the risk of these rare tumours.

Delayed recovery of renal function in patients with acute renal failure due to accelerated hypertension

Five patients with acute renal failure due to accelerated hypertension required regular dialysis treatment for 2-12 months (mean 8.8), before recovering sufficient renal function for dialysis to be withdrawn. Two patients who had prior evidence of chronic renal impairment remained off dialysis for 20 and 27 months before decompensating again to require regular dialysis treatment. Two patients with no prior history of renal disease have remained independent of dialysis for 32 and 48 months. The fifth patient was lost to follow-up after a 7 month dialysis-free period. Delayed recovery of renal function following accelerated hypertension is a distinct possibility and should be considered in such patients before contemplating long term strategies such as renal transplantation.

Low-dose desferrioxamine test for the diagnosis of aluminium-related bone disease in patients on regular haemodialysis

Bone biopsy in an invasive method of diagnosing aluminium related bone disease (ABD). Toxic side-effects have been reported with the currently used 'high-dose Desferrioxamine (DFO) tests.' A low-dose DFO test was evaluated for the diagnosis of ABD in 28 symptomatic patients (13 male) on regular haemodialysis treatment. DFO 0.5 g diluted in 100 ml of 0.9% sodium chloride was given intravenously during the first 2 h of dialysis. Aluminium estimation before (t1) and 48 h after DFO challenge (t2) were made by DC plasma emission spectrometry. Following the DFO test bone biopsy was performed and the specimen stained for aluminium using soluchrome zurine. The DFO test was considered positive if the t2 concentration was 150 micrograms/l or treble the amount of t1. Nineteen patients (8 male) fell into this group and all except two had ABD. Of the nine remaining patients (5 male) who had a negative DFO test none had ABD. We conclude that ABD can be diagnosed safely in the majority of patients using a low-dose DFO test, thereby avoiding toxic side-effects.

Multiple organ failure--a role for plasma exchange?

Two patients with multiple organ failure, septicaemia and a deteriorating clinical course were treated by plasma exchange in addition to standard supportive measures. Dramatic improvements were seen in cardio-respiratory (patient 1), neurological and renal parameters (patient 2) which were attributable to the exchanges. Plasma exchange might be of value as adjunctive therapy where overwhelming septicaemia occurs with multiple organ failure.

Bovine genitourinary tuberculosis revisited

Bovine tuberculosis is now rare in the western world. We report a case of bovine genitourinary tuberculosis causing obstructive renal failure. This combination does not appear to have been previously reported.

Inferior vena caval compression by hepatic cysts: an unusual complication of adult polycystic kidney disease

A case of inferior vena caval compression by hepatic cysts as a complication of adult polycystic kidney disease is presented and its management is discussed.