Is zinc protoporphyrin an indicator of iron-deficient erythropoiesis in maintenance haemodialysis patients?

BACKGROUND

Zinc protoporphyrin (ZPP), a metabolic intermediate generated in the red blood cell by incorporation of zinc instead of iron, has been suggested to be a sensitive and specific parameter of absolute iron deficiency in haemodialysis (HD) patients.

METHODS

We studied 62 HD patients, 29-86 years old, with ZPP levels > 50 mumol/mol haeme (normal value of ZPP < 40 mumol/mol haeme) assessing the value of ZPP as a marker of functional iron deficiency at different cut-off points of ZPP. None of the patients had apparent inflammatory disease, infectious disease, or malignancy. ZPP, haemoglobin, iron and ferritin levels were determined before, and after a 24-week period of once-weekly i.v. administration of 40 mg iron, to determine whether ZPP levels return to normal during adequate iron supplementation (960 mg iron/ patient).

RESULTS

There was no significant change in ZPP levels after iron supplementation in patients with a ZPP > 50 mumol/mol haeme (96.7 +/- 49.8 versus 88.4 +/- 43.5 mumol/mol haeme before and after iron administration respectively, P = n.s.). However, in patients with a ZPP > 90 mumol/mol haeme, there was a significant reduction in ZPP levels (141.2 +/- 54.5 versus 108.0 +/- 48.8 mumol/mol haeme, P < 0.001). Serum ferritin increased significantly in both groups. There was no correlation between ZPP and serum ferritin at any time during the study. There was also no correlation between serum aluminium levels and ZPP and no significant difference in changes in ZPP in patients receiving desferrioxamine therapy compared to those not receiving desferrioxamine therapy. We did find a significant correlation between moderately elevated total blood lead concentrations and ZPP levels at the end of the study. The ZPP levels were not significantly different in the range from 50-110 mumol/mol haeme before and after i.v. iron supplementation in the responders (10% increase of haemoglobin or 20% decrease of the recombinant human erythropoietin dose) compared with the non-responders.

CONCLUSIONS

Our data indicate that ZPP cannot be used to predict the erythropoietic response to iron supplementation. However, ZPP levels may be an indicator of functional iron deficiency due to blockade of the reticuloendothelial iron release in haemodialysis patients.

Can a severe degree of ketoacidosis develop overnight?

Insulin-dependent diabetes mellitus in poor control, alcohol intake associated with extracellular fluid volume contraction, or hypoglycemia may each lead to an increased rate of production of ketoacids. Generally, several days of illness are required before ketoacidosis becomes severe. Two clinical examples are presented to suggest that a severe degree of ketoacidosis may develop over a short period of time, literally overnight. In both examples, there was the ingestion of a modest amount of ethanol. From a quantitative analysis of factors that may influence the rate of production and removal of ketoacids, the following were deduced. Contributing factors to the very rapid development of maximal ketoacidosis could include the absence of a lag period for the conversion of ethanol to acetyl-coenzyme A in the liver and an impaired ability of the brain and kidneys to oxidize ketoacids, especially if these ketoacids are produced very rapidly and/or if less metabolic work is performed by these organs. In special settings, ketoacidosis may develop more rapidly than is generally appreciated.

Antikaliuretic action of trimethoprim is minimized by raising urine pH

This study was designed to test the hypothesis that the antikaliuresis caused by trimethoprim could be diminished by alkalinizing the luminal fluid in the CCD, thereby converting trimethoprim from its cationic, active form to an electroneutral, inactive, form. Trimethoprim-induced inhibition of transepithelial Na+ transport was examined in A6 distal nephron cells by analysis of short circuit current. The voltage-dependence of the trimethoprim-induced block of Na+ channels was examined with patch clamp recordings of A6 cells. The antikaliuretic effect of trimethoprim was examined in vivo in rats pretreated with deoxycorticosterone and with NH4Cl to lower urine pH, and in rats also receiving acetazolamide to raise urine pH. We found that the concentration of trimethoprim required to inhibit the amiloride sensitive component of short circuit current by 50% (IC50) was 340 microM (at pH 8.2) and 50 microM (at pH 6.3). The IC50S of protonated trimethoprim were similar (34 microM at pH 8.2 and 45 microM at pH 6.3). The mean time open for the high selectivity, Na+ channel was reduced from 1679 +/- 387 msec to 502 +/- 98 msec with addition of 10-5 M trimethoprim to patch pipette solution at the resting membrane potential (-Vpipette = 0 mV). further decreases in mean time open were observed as -Vpipette was reduced (that is, apical membrane hyperpolarization) to -40 mV (mean time open = 217 +/- 85 msec) and to -80 mV (mean time open = 69 +/- 13 msec). In vivo, trimethoprim caused a > 50% reduction in potassium (K+) excretion due primarily to a fall in the [K+] in the lumen of the terminal CCD. This effect of trimethoprim was markedly attenuated in an alkaline urine induced by acetazolamide. We conclude that it is the charged, protonated species of trimethoprim which blocks epithelial Na+ channels. Increasing urinary pH decreases the concentration of the charged species of trimethoprim and minimizes its antikaliuretic effect.

Fos is an essential component of the mammalian UV response

Mouse 3T3 fibroblasts lacking c-fos were employed to demonstrate an essential function of the UV-inducible transcription factor AP-1 (Fos/Jun) in the response to the cytotoxic effects of short-wavelength ultraviolet (UVC) radiation. Clonogenic survival and proliferation of cells lacking c-fos were drastically reduced following UV irradiation. This UV hypersensitivity manifests itself primarily in increased cell death, partly by apoptosis, and prolonged recovery time from UV-induced cell cycle arrest. Co-culture with wild-type cells did not ameliorate the hypersensitivity of mutant cells. Transcriptional induction of the c-Fos target genes collagenase I, stromelysin-1 and stromelysin-2 by UV is almost absent in cells lacking c-fos which correlates with a reduced UV induction of AP-1 DNA-binding and transactivation activity. The repair of UV-induced DNA lesions was not affected, as shown by unscheduled DNA synthesis and host cell reactivation assays. These data demonstrate that c-Fos is involved in a novel protective function other than DNA repair against the harmful consequences of UVC.

Ovarian carcinoma metastases to gastrointestinal tract appear to spread like colon carcinoma: implications for surgical resection

OBJECTIVE

To profile the incidence of mesenteric lymph node metastases in patients with ovarian carcinoma and metastases to the gastrointestinal tract in order to determine the optimal technique for surgical debulking.

METHODS

The slides and charts of all patients with ovarian carcinoma who had undergone bowel resection were retrospectively reviewed and follow-up information was obtained.

RESULTS

Of 100 separate bowel resections 44% had penetration of metastases to the muscularis, 18% had invasion through the submucosa, 4% had mucosal perforation, and two patients had clinical perforation. Fifty-five percent of all resections demonstrated lymph-vascular space invasion (LVSI). In the 33 specimens which included pathologic analysis of mesenteric lymph nodes, 79% had positive LVSI, which correlated with the presence of mesenteric lymph node metastases (P = 0.05) but not histologic grade (P = 0.20). When surgery was performed for secondary debulking, the frequency of mesenteric node metastasis was higher (P = 0.15). There was a trend for patients with positive mesenteric nodes to fail sooner (median survival, 20 months vs 32 months).

CONCLUSIONS

Because ovarian carcinoma metastases to the gastrointestinal tract are frequently associated with metastases to mesenteric lymph nodes, gynecologic oncology surgeons may wish to consider resection of the mesentery in a wedge fashion similar to current standards of resection for primary bowel carcinoma in cases in which a bowel resection is being performed with the intent to debulk to zero visible residual disease.

Design and recruitment for retinoid skin cancer prevention (SKICAP) trials. The Southwest Skin Cancer Prevention Study Group

The retinoid skin cancer prevention (SKICAP) trials are a set of double-blind, randomized, placebo-controlled clinical trials. The SKICAP-actinic keratoses (AK) trial tests the hypothesis that daily supplementation of retinol (25,000 IU) for 5 years reduces the incidence of skin cancers in high-risk individuals, those with a history of greater than ten clinically or pathologically diagnosed AK and, at most, one prior pathologically confirmed cutaneous squamous cell carcinoma (SCC) or basal cell carcinoma (BCC). The SKICAP-SCC/BCC (S/B) trial tests the hypothesis that daily supplementation of retinol (25,000 IU) or 13-cis-retinoic acid (5 or 10 mg) for 3 years reduces skin cancer incidence in very high-risk individuals, those with a history of at least four pathologically confirmed SCCs or BCCs. Between 1984 and 1988, 2800 participants were enrolled at two clinics on the SKICAP-AK trial; and between 1985 and 1990, a total of 719 participants were enrolled at four clinics on the SKICAP-S/B trial. The initial recruitment strategy was referral by dermatologists, but low accrual necessitated the use of other strategies to achieve enrollment goals, which included involving additional clinics and using paid trial-specific advertisements in print and electronic media. Thirteen % of the SKICAP-AK participants and 36% of the SKICAP-S/B participants were enrolled through dermatologist referral, whereas paid advertisements resulted in enrollment of 87% of SKICAP-AK and 43% of SKICAP-S/B participants. A population-based skin cancer registry was used to identify and enroll the remaining 21% of the SKICAP-S/B participants.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of age and gender on pituitary-adrenocortical responsiveness in humans

This study compared plasma concentrations of adrenocorticotropin (ACTH) and cortisol in young men (N = 10, mean age 24.4 years), young women (N = 10, mean age 25.4 years), old men (N = 8, mean age 81.6 years) and old women (N = 8, mean age 83.5 years) under basal resting conditions and after stimulation with either human corticotropin-releasing hormone (hCRH, 100 micrograms iv) or a combined injection of hCRH (100 micrograms) and arginine vasopressin (VP, 0.5 IU iv). Basal secretion of cortisol did not differ among groups, but basal concentrations of ACTH were diminished in young women (p < 0.01), indicating an enhanced adrenal sensitivity to ACTH in these subjects. Pituitary responses to hCRH did not differ between young men and women. However, responses to hCRH/VP were stronger in the young females (p < 0.01), suggesting an enhanced pituitary responsiveness to the augmenting effect of VP on ACTH release in this group. Pituitary-adrenal secretory responses were greater in old than in young men after sole injection of hCRH (p < 0.05) and even more so after combined injection of hCRH/VP (p < 0.01). In old women, pituitary-adrenal secretory responses were also greater than in young women (p < 0.05). But, in particular for responses to hCRH/VP, these effects were less distinct than within the men. Results indicate an enhancing effect of age on pituitary responsiveness to the hypothalamic secretagogues hCRH and VP, modulated by the subject's gender.

Interruption of cytokine networks by poxviruses: lessons from myxoma virus

Myxoma virus is an infectious poxvirus pathogen that induces a virulent systemic disease called myxomatosis in European rabbits. The disease is rapidly and uniformly fatal to susceptible rabbits and is characterized by generalized dysfunction of cellular immunity and multiple interruptions of the host cytokine network. A number of virus genes are classified as virulence factors because virus constructs bearing targeted gene disruptions induce attenuated disease symptoms. Many of these genes encode proteins that interact directly with effector elements of the host immune system. Included among these immunosubversive viral proteins are secreted mimics of host ligands or regulators (virokines) and homologues of cellular cytokine receptors (viroceptors). Five examples of these immune modulator proteins encoded by myxoma virus are reviewed: (1) myxoma growth factor, a member of the epidermal growth factor ligand superfamily; (2) SERP-1, a secreted serine proteinase inhibitor; (3) M11L, a receptor-like surface protein; (4) T2, a tumor necrosis factor receptor homologue; and (5) T7, an interferon-gamma receptor homologue. The origin of viral strategies designed to subvert immune regulation by host cytokines is considered in the context of the biology of myxoma virus within immunocompetent hosts.

Prevalence of antibodies against hepatitis A virus among new immigrants in Israel

Israel, located in a region endemic for hepatitis A virus (HAV), recently absorbed a large population of immigrants who came from the former USSR. To assess the risk of high morbidity in this population a serosurvey of HAV antibodies was undertaken. Serum samples were collected from 965 new immigrants, of whom 664 came from the European, non-endemic region, and 301 from the Asian and Caucasian endemic regions of the former Soviet Union. They were compared to 240 Israelis. Each population was divided into six age groups: 1-9, 10-19, 20-29, 30-39, 40-49, and 50 years of age and older. The Asian/Caucasian immigrants and the Israeli population were found to share similar characteristics. In both groups, antibodies to HAV (anti-HAV) were present in the 1-9-year-old age group and reached maximum prevalence (90% and 86.7%, respectively) in the 20-29-year-old age group. In contrast, among the European immigrants anti-HAV was first found in the 10-19-year-olds and peaked (93%) in the age group of 50 years and older. It is concluded that immigrants originating from the European part of the former USSR may require vaccination against hepatitis A.

Vasectomy in the rat--effects on mineral metabolism, with emphasis on renal tissue minerals and occurrence of urinary stones

An increased stone frequency and hypotestosteronemia after vasectomy were reported and suggest development of some disturbance of homeostasis of minerals and hormones. The objective of the present study in the rat was to assess the effects of vasectomy (n = 14) and vasovasostomy (n = 12) on gonadal state, intestinal absorption of minerals and mineral concentrations in serum, urine and 3 renal tissue regions. Sham-operated animals (n = 12) served as controls. Seven months after surgery the combined results show that vasectomy induced a significant decrease in gonadal weight, but not in serum and urinary testosterone; serum magnesium was decreased (p = 0.014 versus controls) and phosphaturia was increased (p = 0.025), whereas serum calcium, parathyroid hormone and urinary cyclic AMP were unchanged. Also, after vasectomy there was a significant accumulation of phosphorus, calcium and magnesium in renal papillae and additionally of phosphorus in the renal cortical and medullary region; oxalate was unchanged. Renal stones containing calcium phosphate were found in 2 vasectomized rats, but in none of the vasovasostomized ones. In contrast, in vasovasostomized rats, mineral accumulation in renal tissues was abolished, and the associated concentration of serum free testosterone was 3 times higher (p = 0.018) than in control rats. It was concluded that vasectomy in the rat 1) may not be neutral to gonadal function in terms of gonadal weight; 2) disturbs the homeostasis of magnesium, calcium and phosphorus at the level of the kidney; and 3) induces mild hypomagnesemia and marked hyperphosphaturia in the presence of normal parathyroid gland function. It is suggested that these sequelae of vasectomy and vasovasostomy may be traced back to a disturbance of autonomous nerve tone.

[Brain ultrasonography in diagnosis of intrauterine infections and of neonatal chromosomal disorders]

Ultrasonography of the brain is a primary, frequently used technique for the diagnosis of brain lesions in the neonate. Echogenic blood vessels in the thalamus and basal nuclei are an unusual finding in an ultrasonographic homogeneous area. We describe 2 neonates with echogenic blood vessels in this area who are, to our knowledge, the first such cases described in Israel: 1 with trisomy 13 and the other with a congenital cytomegalovirus infection. We focus pediatric attention on this simple, readily available method for diagnosing intrauterine infections and chromosomal aberrations in the neonate.