SAP Levels Research Articles

Effects of salinity and convective rhizome ventilation on amino acid and carbohydrate patterns of Phragmites australis populations in the Neusiedler See region of Austria and Hungary

Parameters of convective ventilation and also the content and composition of free amino acids and free carbohydrates in roots, basal culm internodes and leaves were investigated in five stands of Phragmites australis that were subjected to different growth conditions and salinity levels. Shoot length, stem diameter and productivity decreased with increasing salinity. These morphometric variations in turn affected parameters of convective ventilation and amino acid patterns. Phragmites populations growing at the highest salinity levels possessed the lowest rhizome conductivities, which was probably caused by their more pronounced xeromorphic growth. High counterpressures of the rhizome system and low stem diameters were limiting factors for convective flows. The Phragmites stand with lowest flow rate and ventilation efficiency had the highest percentage of alanine, serine and γ‐aminobutyric acid (55% of total free amino acids) in its roots, indicating hypoxic stress in basal plant parts. Increasing salinity was connected with significantly higher fractions of glutamine (in basal culm internodes), glutamate (in roots) and proline (in both) as well as slightly increasing osmolality of plant sap. However, total contents of free amino acids and carbohydrates were low, and not related to either salinity level or osmolality of plant sap. This suggests that they might not have an important, direct role as an osmolyte in P. australis. Stand‐specific variations in amino acid and carbohydrate patterns of leaves were negligible. Ratios of amino acids to carbohydrate were positively related to potential N supply. It is concluded that (1) salinity affects convective rhizome ventilation by varying the reed morphometry, and (2) the pattern of free amino acids responds characteristically to conditions of salinity and hypoxic growth.

An Assessment of Basic Education under the Social Action Plan in Pakistan

Educational expenditure as a percentage of GDP has indeed been protected and over the first phase of SAP (1993-1996) has increased by about 0.2 per cent of GDP. However, despite SAP protection, it declined to the pre- SAP level for 1998-99. While there is evidence that, in some aspects, the gender and regional gaps have closed, the poorest continue to be excluded from schooling, the rural female income gap in schooling has widened and, if the poor do attend, they are the most likely to drop out. Also, net enrollment rates for boys and girls actually declined over the first SAP period.

High aspartyl proteinase production and vaginitis in human immunodeficiency virus-infected women.

Vaginal isolates of Candida albicans from human immunodeficiency virus-positive (HIV+) and HIV- women with or without candidal vaginitis were examined for secretory aspartyl proteinase (Sap) production in vitro and in vivo and for the possible correlation of Sap production with pathology and antimycotic susceptibility in vitro. HIV+ women with candidal vaginitis were infected by strains of C. albicans showing significantly higher levels of Sap, a virulence enzyme, than strains isolated from HIV+, C. albicans carrier subjects and HIV- subjects with vaginitis. The greater production of Sap in vitro was paralleled by greater amounts of Sap in the vaginal fluids of infected subjects. In an estrogen-dependent, rat vaginitis model, a strain of C. albicans producing a high level of Sap that was isolated from an HIV+ woman with vaginitis was more pathogenic than a strain of C. albicans that was isolated primarily from an HIV-, Candida carrier. In the same model, pepstatin A, a strong Sap inhibitor, exerted a strong curative effect on experimental vaginitis. No correlation was found between Sap production and antimycotic susceptibility, as most of the isolates were fully susceptible to fluconazole, itraconazole, and other antimycotics, regardless of their source (subjects infected with strains producing high or low levels of Sap, subjects with vaginitis or carrier subjects, or subjects with or without HIV). Thus, high Sap production is associated with virulence of C. albicans but not with fungal resistance to fluconazole in HIV-infected subjects, and Sap is a potentially new therapeutic target in candidal vaginitis.

Heterotopic Ossification: Diagnosis and Management Current Concepts and Controversies

HO is a pathologic process in which soft tissues undergo ossification. The etiology is unknown. Patients with neurologic deficits develop HO in the proximal joints. An incidence of 20% to 30% is commonly reported; 8% to 10% of these patients develop severe functional limitations. Routine prophylaxis in patients with SCI cannot be justified. Early diagnosis and treatment with EHDP or other anti-inflammatory medications have been shown to result in good functional outcomes. Elevated SAP levels and positive radionuclide scan, in addition to restriction of joint ROM, are indicative of HO formation. Role of other anti-inflammatories, radiation, and early surgical excision without bone maturity in these patients need to be studied further. A small percentage of patients require surgery to improve function. Joint manipulation to produce pseudoarthrosis is not indicated in patients with SCI.

3,4-Benzpyrene affects the sexual behaviour of rats across the generations

Chlorinated paraffins are a group of chemicals derived from n-paraffins containing between 10 and 30 carbon atoms which are chlorinated to between 40 and 70% (w/w). Representative grades were tested for acute oral toxicity and skin irritancy in rats, eye irritancy in rabbits, and potential mutagenic effects in two in vitro tests. The effects of one grade (14–17 carbon atoms, 52% chlorinated) which is manufactured in high-tonnage quantities, was evaluated in a 90-day feeding study in rats and dogs, and its tissue retention and elimination was determined in the rat. Chlorinated paraffins are of low acute oral toxicity. Slight, reversible skin and eye irritations were produced by shorter carbon chain derivatives only and no type showed any evidence of mutagenic potential. Subacute administration of 500, 2500, and 5000 ppm reduced diet palatability to rats. Increases in SGPT or SAP levels, liver weight, and smooth endoplasmic reticulum in hepatocytes were seen in rats and dogs: “no-effect” diet levels were 250 and 300 ppm, respectively. Chlorinated paraffin accumulates primarily in the abdominal fat of rats at concentrations which never exceed those in diet (unlike certain other chlorinated organic compounds); its half-life in abdominal fat is about 8 weeks, when untreated diet is offered. On the currently available evidence, in view of their slight toxicity and the low human dietary levels in comparison to the maximum “no-effect” levels in rats and dogs, it is concluded that chlorinated paraffins present no toxicological risk to man despite their continued manufacture and widespread low-level occurrence in the environment.

Expression of a biologically active recombinant mouse IL-1 receptor antagonist and its use in vivo to modulate aspects of the acute phase response.

Recombinant mouse IL-1receptor antagonist protein (rmIL-1ra) was expressed in Escherichia coli. In vivo administration of rmIL-1ra, in a casein-induced murine model of acute inflammation, completely abolished the hepatic induction of the mRNAs specifying serum amyloid A1 (A-SAA1) and A-SAA2 for up to 12 h, indicating that hepatic A-SAA mRNA synthesis is totally IL-1 driven. A-SAA protein, however, was present in the serum of rmIL-1ra-treated casein-stimulated mice (although at lower levels than in untreated casein-stimulated mice) at 12 h indicating that extrahepatic A-SAA synthesis is driven in part by factors acting independently of IL-1. Hepatic mRNA levels of the other mouse acute phase reactants (APRs), serum amyloid P component, C-reactive protein, alpha1-acid glycoprotein, and C3 were also induced with casein after 12 h, as were serum protein levels of SAP and C3. These inductions were only partially inhibited by rmIL-1ra, indicating that hepatic expression of the latter APRs (unlike that of A-SAA) is driven partly by IL-1 and partly by factors acting independently of IL-1. Hepatic mRNA levels of the negative APRs apolipoprotein A-I and serum albumin were down-regulated 12 h after casein stimulation. rmIL-1ra partially restored serum albumin mRNA levels but not apo A-I mRNA levels, indicating differential regulation of these negative APRs. The rmIL-1ra will be useful in studies of IL-1-mediated gene regulation in murine models of inflammation.

Root Uptake and Xylem Translocation of Pesticides from Different Chemical Classes

A pressure-chamber technique was used to study the root uptake and xylem translocation of some fungicides, herbicides and an insecticide from different chemical classes in detopped soybean roots. Physiological parameters such as K+ leakage from roots, K+ concentrations in the xylem sap, and protein and ATP levels in the root cells were measured so as to evaluate any potential damage of this technique to the root system. HPLC was used to quantify the compounds in the xylem sap. The pressure-chamber technique has proved useful to study the root uptake and translocation of pesticides, does not damage the root system, and allows one to obtain appreciable volumes of xylem sap that can be analysed directly by HPLC, thus avoiding dependence on the availability of radio-labelled compounds. The concentration of each pesticide in the xylem sap showed a steady-state kinetic profile. Non-linear regression analysis was used to calculate the steady-state concentration and the time required to achieve 50% of the steady-state concentration (TSSC50). TSSC50 was well correlated with log Kow; the more lipophilic the compound the more time was required to reach the steady-state concentration. The efficiency of translocation was assessed by the transpiration stream concentration factor (TSCF) and a non-linear relationship between TSCF and log Kow was observed. The highest TSCF values were measured for those compounds with log Kow values around 3, a lipophilicity value similar to that reported earlier in an analogous experiment with detopped soybean plants but slightly higher than that reported in earlier experiments with intact barley plants. Lower TSCF values were obtained with chemicals with log Kow values below as well as above 3. © 1997 SCI.

Skeletal alkaline phosphatase: a marker for individual follow-up in patients with advanced prostatic cancer.

Skeletal alkaline phosphatase (sAP) is a tumor marker indicating osseous metastases, e.g. of prostate cancer. Sera of healthy men and patients with benign prostatic hyperplasia (BPH), localized and advanced prostatic cancer (PCa) were analyzed with Tandem-R-Ostase and prostate-specific antigen (PSA). No significant differences were found in sAP levels between healthy men and patients with BPH and localized PCa, but there was a significant difference with the group of patients with advanced PCa. In some cases, the individual follow-up was better and earlier with sAP compared to PSA. It is possible to discriminate between localized and advanced PCa with sAP. The individual follow-up shows in 30% of patients with advanced PCa an earlier increase in sAP, compared to PSA, during progression of disease.

Ultrastructural localization of the secretory aspartyl proteinase in Candida albicans cell wall in vitro and in experimentally infected rat vagina.

Detection and ultrastructural localization of aspartyl proteinase (Sap) in Candida albicans experimentally infecting rat vagina were studied. Two Sap-positive (Sap+) and one Sap-negative (Sap-) strains of the fungus, endowed with high and low experimental vaginopathic potential, respectively, were used. Both Sap+ strains produced consistent Sap levels in the rat vagina, while the Sap- strain did not produce any measurable Sap. Electron microscopy of thin sections of chemically-fixed vaginal scrapings showed clear evidence of hyphae of proteolitic strains of C. albicans invading the keratinized epithelial cell layer of the vagina. The fungal cells exhibited a pronounced fibrillar layer on the cell wall with a marked intermixing of fungal and vaginal materials especially pronounced at the hyphal tip. Post-embedding immunogold techniques with the use of anti-Sap polyclonal and the specifically generated monoclonal antibody GF1 showed that Sap was essentially localized in the cell wall of C. albicans early during infection, in a cytological pattern mirroring Sap localization in C. albicans cells grown in Sap-inductive media in vitro. In summary, the data offer a new biochemical and ultrastructural evidence that Sap is actively secreted during experimental rat vaginitis by C. albicans. Cell wall localization of Sap is probably inherent to this active secretion process.

Xylem exudation is related to nitrate assimilation pathway in detopped maize seedlings: use of nitrate reductase and glutamine synthetase inhibitors as tools

The xylem exudation of detopped 7-d-old seedlings of Zea mays L. doubled when KCl was present in the root medium compared to seedlings maintained on water. It was further enhanced when KCl was replaced by nitrogen compounds such as nitrate, ammonium and glutamine. The role of the nitrate assimilation pathway on the enhancement of xylem exudation rate was investigated using tungstate, an inhibitor of nitrate reductase (NR) activity, and phosphinothricin or methionine sulphoximine, inhibitors of glutamine synthetase (GS) activity. The sap levels of NO 3 - , NH 4 + , glutamine, and asparagine was used to ascertain the in vivo inhibition of both enzymes. The tungstate effects were also checked by measuring leaf in vitro NR activity and NR protein content. Xylem exudation rate of detopped seedlings fed with KNO 3 decreased when the nitrate assimilation pathway was blocked either at the NR or at GS sites. This decrease was prevented when urea (acting as NH 4 + supply) was given simultaneously with tungstate. KNO 3 does not act directly on exudation, but through the involvement of NH 4 + . The involvement of glutamine was also shown since GS inhibition resulted in a cancellation of the enhancing effect of KNO 3 on exudation. As change of exudation rate was not linked to change in sap osmolarity, it is assumed that the assimilation chain could modify root water conductance. The role of glutamine was discussed.

Efficacy and tolerability of a new formulation of oral tiludronate (tablet) in the treatment of paget's disease of bone

We sought to assess efficacy and safety of a new oral formulation (tablet) of tiludronate in Paget's disease of bone. We studied 128 patients with Paget's disease in an open-label uncontrolled trial. Patients received a daily dose of 400 mg oral tiludronate (two tablets). Treatment was for 6 months. Serum alkaline phosphatase activity (SAP) and fasting urinary excretion of hydroxyproline/creatine (OH/Cr) were measured every 3 months, as were biochemical parameters reflecting renal, hepatic, and hematologic functions. Analgesic efficacy was self-evaluated from a visual analog scale (VAS). Statistical analysis revealed a significant reduction from baseline in SAP and OH/Cr levels, as well as VAS scores. In the whole population with evaluation under treatment, there was a reduction in initial SAP activity after 3 months (47.2 +/- 2.2%, mean +/- SEM) and 6 months (58.3 +/- 2.3%). In the population with SAP levels above twice the upper limit at inclusion and with evaluation at month 3 and month 6 (n = 96), the reduction in SAP levels was 49.3 +/- 2.4% after 3 months and of 59.5 +/- 2.6% after 6 months (ANOVA time effect, p = 0.0001). Aside from mild gastrointestinal disturbances, as experienced with other oral bisphosphonates, clinical tolerance was good. Exhaustive biochemical investigation failed to reveal significant toxicity of tiludronate tablets at the dose of 400 mg/day. The dose of 400 mg daily of this new formulation appears to be a satisfactory tiludronate regimen for the treatment of Paget's disease of bone.

Root hydraulic conductivity and xylem sap levels of zeatin riboside and abscisic acid in ectomycorrhizal Douglas fir seedlings.

Mechanistic hypotheses to explain mycorrhizal enhancement of root hydraulic conductivity (Lp ) suggest that phosphorus (P) nutrition, plant growth substances and/or altered morphology may be responsible. Such ideas are based on work with VA (vesicular-arbuscular) mycorrhizas. Since VA mycorrhizas and ectomycorrhizas differ in many respects, they may alter host plant water uptake via different mechanisms. This paper examines LT in various ectomycorrhizal associations while considering factors which are important to the VA mycorrhizal effect on Lp . Douglas fir Pseudotsuga menziesii (Mirb.) Franco] seedlings inoculated with the ectomycorrhizal fungi Laccaria bicolor (Maire) Orton and Hebeloma crustuliniforme (Bull, ex St. Amans) Quel. and non-inoculated seedlings infected naturally with Thelephora were grown under three low levels of P fertilization (1, 10 and 100 fim P). Seedling morphology, tissue P levels, Lp and plant growth substance levels in xylem sap were measured after nine months growth. Increased tissue P and decreased root/shoot ratio correlated with increased Lp in each of the mycorrhizal treatments. When adjusted for the effect of these two factors, Lp of Laccaria and Hebeloma seedlings was still lower than the Thelephora seedlings. In a subsequent experiment, the Lp of seedlings with Hebeloma and Rhizopogon vinicolor Smith mycorrhizas was compared to the Lp of non-mycorrhizal seedlings (grown at 100 mM P) and no differences were found among treatments. The lack of an ectomycorrhizal effect on Lp is quite different from the enhancement of host Lp by VA mycorrhizas. Zeatin riboside concentrations of Thelephora- and Hebeloma-iniected seedlings were similar, yet higher than with Laccaria. There was no relationship between plant growth substances and Lp in ectomycorrhizal Douglas fir, despite lower zeatin riboside concentrations for Laccaria-inoculated plants.

Response of osteogenic sarcoma to the combination of etoposide and cyclophosphamide as neoadjuvant chemotherapy

A Phase II study of the combination of etoposide (VP-16) and cyclophosphamide (CPM) was conducted in an attempt to identify active and potentially less toxic agents for treating patients with osteogenic sarcoma (OS). VP-16 was given as a 72-hour infusion for a total dose of 600 mg/m2. CPM was given as six pulses of 300 mg/m2 every 12 hours for a total dose of 1800 mg/m2. Seventeen newly diagnosed patients, including five (29%) with metastatic disease, were evaluated before and after two courses of VP-16 and CPM for clinical, radiologic, and biochemical (serum alkaline phosphatase [SAP]) responses of the primary tumor and metastases. Fifteen (88%) patients achieved complete or partial clinical responses. Fourteen (82%) patients achieved radiologic responses. Thirteen (87%) of 15 patients with higher than normal SAP levels for their age showed partial or complete responses. Three (60%) of the five patients with metastatic disease achieved complete or partial responses. The only major toxicity was myelosuppression, which led to 21 (62%) brief admissions after 34 courses of chemotherapy for intravenous antibiotic therapy for fever and neutropenia, without associated mortality. It was concluded that the combination of VP-16 and CPM is effective chemotherapy for both primary and metastatic OS. Although myelosuppression is inevitable, it is rapidly reversible in the drug dosages used. Further studies are needed to evaluate the effect of these drugs in combination with established agents in improving the disease-free survival of patients with OS.

Nitrogen fixation (N‐15 dilution) with soybeans under Thai field conditions. IV. Effect of N addition and Bradyrhizobium japonicum inoculation in soils with indigenous B. japonicum populations

The effects of Bradyrhizobium japonicum inoculation and pre‐plant additions of N fertilizer on soybean (Glycine max L. Merrill) yields and levels of N2 fixation were studied under field conditions at two sites in Thailand. Bacterial inoculants were composed of B. japonicum strains selected for high N2 fixation levels in Thai soils. Nitrogen fertilizer addition rates used were from 0 to 250 kg N/ha in 50 kg N/ha increments. At the Chiang Mai site in northern Thailand, bacterial inoculation increased nodule weights on plants receiving 100 kg N/ha or less. Increases in nodule parameters due to inoculation were evident at 45 d after planting (DAP) but disappeared by 60 DAP. Addition of N fertilizers decreased the incidence of nodulation and sap ureide contents and decreased the contribution of N2 fixation to the N content of plants at maturity as measured by N‐15 isotope dilution methods. At the Kampang Saen site in central Thailand, bacterial inoculation had significant positive effects on nodule numbers and weights, ARA, sap ureide contents and levels of N2 fixed as measured by N‐15 isotope dilution methods. Addition of N fertilizers at this site also reduced the effectiveness of N2‐fixing symbioses. It was concluded that small additions of N fertilizer added before planting did not significantly decrease N2 fixation levels, but did have a significant positive effect on plant growth. Larger N additions would reduce N2 fixation levels in excess of the benefits of adding more N in chemical form.

Chromosomal location of the gene encoding the murine acute-phase protein serum amyloid P-component (SAP)

A full-length cDNA clone, pmSAP3, encoding, the serum P component (SAP), has been used to search for DNA fragment length variation among mouse strains previously analyzed for differences in endogenous SAP levels. Three alleles were found using EcoRI-digested DNA. The finding of a single 5.4-kb fragment, allele d, in DNA from DBA/2J mice suggests the presence of a single Sap locus. Segregation of DNA fragment associated with Sapb and Sapd alleles was analyzed in three sets of recombinant inbred (RI) strains. The strain distribution pattern found for the Sap alleles was identical to that of alleles of Ly-9 in 43 individual RI strains, suggesting tight linkage with Ly-9 on mouse chromosome 1. In the BXD RI strains, the SDP of the Sap locus, defined by the difference in the endogenous SAP level, is also identical to the SDP of the DNA fragments. We propose to redesignate the Sap locus to include both the structural element defined by the DNA polymorphism and the regulatory element involved in the regulation of SAP synthesis. The Sap locus is the major genetic element contributing to the regulation of SAP production. Other genetic factors are also involved, as shown by the presence of nonparental phenotypes in the individual BXH RI strains.

Yields of Greenhouse Tomatoes Managed to Maintain Specific Petiole Sap Nitrate Levels

Abstract ‘Caruso’ tomatoes (Lycopersicon esculentum Mill.) were grown in peat-perlite-vermiculite in a greenhouse with five nitrate-nitrogen (NO3-N) fertilization concentrations in irrigation waters managed to maintain 200, 400, 600, 900, or 1200 µg NO3-N/ml in petiole sap as determined by weekly NO3-N quick tests. Nitrate-N fertilization concentrations immediately were increased 50% when petiole sap NO3-N levels first fell below these target levels; thereafter, NO3-N fertilization concentrations were increased only after petiole sap levels fell below target levels for 2 consecutive weeks. The critical target level of sap NO3-N was defined as the lowest petiole sap NO3-N target level producing maximum marketable fruit yields. Total fruit yields increased with increasing petiole sap NO3-N target levels through 1200 µg·ml–1. Marketable fruit yields were maximized at 3.2 kg/plant, with an estimated critical sap NO3-N target level of 1105 µg·ml–1. Application of the sap NO3-N management rules used in this experiment resulted in five adjustments in N fertilization concentrations over the 27-week crop cycle, with an average of 4.5 weeks between adjustments. This approach to the management of N fertilization based on the sap NO3-N level of the crop has potential to provide significant benefits in improved N use and crop productivity at a modest cost.

Serum amyloid P-component levels in patients with malignancy.

The P component of amyloid is a normal serum protein designated SAP. SAP has substantial homology with C-reactive protein (CRP). However, unlike CRP, SAP is not an acute-phase reactant in man. Recent studies have established SAP as a major acute-phase protein in mice. Moreover, mice which have received tumour implants have also been found to have raised serum concentrations of SAP. The aim of the present study was to determine possible association between the serum level of SAP and human cancer. We found that patients with carcinoma of the breast have significantly increased serum concentrations of SAP. Moreover, in these patients SAP levels correlated with the severity of the disease. Patients with carcinoma of the colon, however, did not differ from healthy individuals in the serum level of SAP. Possible explanations for this discrepancy are discussed.

Acromegaly in the Dog

The main characteristic findings in canine acromegaly are a visible increase in soft tissue mass, prominent skin folds, abdominal enlargement, and/or radiographic evidence of an increase in soft tissue mass in the orolingual, oropharyngeal, and orolaryngeal region. Acromegalic dogs almost invariably show some degree of respiratory stridor. Enlargement of the interdental spaces can be seen, but it is felt that these changes are less specific for the disease. Other possible findings include hyperglycemia, PU/PD, elevated SAP levels, and lowered PCV. For a conclusive diagnosis, the demonstration of elevated GH levels and, preferably, the demonstration of nonsuppressibility of these high GH levels is required. Basal plasma GH levels in acromegalic dogs varies considerably (for example, from 10 ng per ml to approximately 1500 ng per ml). GH-dependent circulating growth factor (that is, insulin-like growth factor I) is drastically elevated. Acromegaly is encountered in intact female dogs that were treated with progestagens to prevent estrus and in dogs during diestrus (progesterone phase). Progestagen withdrawal and/or ovariohysterectomy will result in a reduction of plasma GH and GH-dependent insulin-like growth factor concentrations and appreciable clinical improvement.

Study of the evolution of acute phase reactants and of thromboxane and prostacyclin during calcium pyrophosphate-induced pleurisy in the rat.

By using a clearly defined model of acute inflammation in rats, CaPP-induced pleurisy, we compared the evolution of four APR levels (Hp, HpX, alpha 2M, SAP) at a local and peripheral site. At the same time we studied thromboxane and prostacyclin concentrations in pleural exudate. The levels of APR have shown a progressive increase up to 24 h. For alpha 2M, Hp, HpX the increase in serum concentration was more rapid than in exudate, whereas the evolution of SAP level was parallel in the intra and extra-vascular compartments. On the other hand the levels of albumin and transferrin which are not APR remained constant in serum and also in exudate from 6 h to 24 h. Thromboxane and prostacyclin levels reached a peak during the first two hours of the inflammatory reaction followed by a rapid decreased. These prostanoids may be considered as early and transient mediators of acute inflammation, whereas the acute phase proteins studied have a more prolonged role in the inflammatory reaction.

The toxicological effects of chlorinated paraffins in mammals

Chlorinated paraffins are a group of chemicals derived from n-paraffins containing between 10 and 30 carbon atoms which are chlorinated to between 40 and 70% (w/w). Representative grades were tested for acute oral toxicity and skin irritancy in rats, eye irritancy in rabbits, and potential mutagenic effects in two in vitro tests. The effects of one grade (14–17 carbon atoms, 52% chlorinated) which is manufactured in high-tonnage quantities, was evaluated in a 90-day feeding study in rats and dogs, and its tissue retention and elimination was determined in the rat. Chlorinated paraffins are of low acute oral toxicity. Slight, reversible skin and eye irritations were produced by shorter carbon chain derivatives only and no type showed any evidence of mutagenic potential. Subacute administration of 500, 2500, and 5000 ppm reduced diet palatability to rats. Increases in SGPT or SAP levels, liver weight, and smooth endoplasmic reticulum in hepatocytes were seen in rats and dogs: “no-effect” diet levels were 250 and 300 ppm, respectively. Chlorinated paraffin accumulates primarily in the abdominal fat of rats at concentrations which never exceed those in diet (unlike certain other chlorinated organic compounds); its half-life in abdominal fat is about 8 weeks, when untreated diet is offered. On the currently available evidence, in view of their slight toxicity and the low human dietary levels in comparison to the maximum “no-effect” levels in rats and dogs, it is concluded that chlorinated paraffins present no toxicological risk to man despite their continued manufacture and widespread low-level occurrence in the environment.