spr-2, a suppressor of the egg-laying defect caused by loss of sel-12 presenilin in Caenorhabditis elegans, is a member of the SET protein subfamily

Presenilin plays critical roles in the genesis of Alzheimer's disease and in LIN-12/Notch signaling during development. Here, we describe a screen for genes that influence presenilin level or activity in Caenorhabditis elegans. We identified four spr (suppressor of presenilin) genes by reverting the egg-laying defective phenotype caused by a null allele of the sel-12 presenilin gene. We analyzed the spr-2 gene in some detail. We show that loss of spr-2 activity suppresses the egg-laying defective phenotype of different sel-12 alleles and requires activity of the hop-1 presenilin gene, suggesting that suppression is accomplished by elevating presenilin activity rather than by bypassing the need for presenilin activity. We also show that SPR-2 is a nuclear protein and is a member of a protein subfamily that includes human SET, which has been identified in numerous different biochemical assays and at translocation breakpoints associated with a subtype of acute myeloid leukemia.

Vasopressin V1a receptor antagonism does not reverse adrenocorticotrophin-induced hypertension in the rat

1. The role of arginine vasopressin (AVP) was examined in adrenocorticotrophin (ACTH)-induced hypertension in Sprague-Dawley rats using the non-peptide AVP V1a receptor antagonist OPC 21268. 2. In an acute study, six rats were pretreated with ACTH for 11 days and direct arterial blood pressure (4 h), plasma osmolality and electrolyte concentrations were measured after OPC 21268 gavage. In a chronic study, 40 rats were randomly divided into four groups: (i) sham injection + sham gavage; (ii) ACTH + sham gavage; (iii) sham injection + OPC 21268; or (iv) ACTH + OPC-21268 for 16 days. Systolic blood pressure (SBP), water intake, urine volume (UV), urine osmolality and electrolytes, food intake, bodyweight and plasma osmolality and electrolyte concentrations were measured. 3. In the acute study, direct mean arterial blood pressure did not change with OPC 21268 (122+/-2 and 120+/-3 mmHg at 0 and 240 min, respectively). 4. In the chronic study, OPC 21268 did not affect ACTH-induced rises in blood pressure (from 125+/-2 (control) to 145+/-5 mmHg (group 4) compared with 122+/-3 (control) to 149+/-5 mmHg (group2)). Water intake and UV increased (from 29+/-2 to 83+/-6 mL/day; and from 5+/-1 to 36+/-5 mL/day, respectively) and the change in bodyweight decreased from 0+/-2 to -107+/-7 g. 5. These results suggest that AVP (at the V1a receptor) does not play a significant role in the maintenance of ACTH-induced hypertension.

Role of nitric oxide in adrenocorticotrophin-induced hypertension: L-arginine effects reversed by N-nitro-L-arginine

1. L-arginine prevents adrenocorticotrophin (ACTH)-induced hypertension in the rat. To confirm that this effect is mediated through the nitric oxide (NO) system, we examined whether N-nitro-L-arginine (NOLA) could reverse the L-arginine-induced blockade of ACTH-induced hypertension. 2. Blood pressure and metabolic parameters were examined in sham-, ACTH-, L-arginine + sham-, NOLA + sham-, ACTH + L-arginine- and ACTH + L-arginine + NOLA-treated Sprague-Dawley rats (n = 40). 3. Adrenocorticotrophin treatment increased systolic blood pressure (SBP), water intake and urine output and decreased bodyweight. N-Nitro-L-arginine alone increased SBP without affecting metabolic variables. L-Arginine alone did not affect blood pressure. The SBP was lower in L-arginine + ACTH- than ACTH-treated rats (P < 0.001), but was higher following ACTH + L-arginine + NOLA than ACTH + L-arginine (P < 0.05). 4. N-Nitro-L-arginine reversed the blood pressure-lowering effect of L-arginine in ACTH-induced hypertension in the rat, supporting the notion that NO plays a role in the hypertension.

Transcatheter closure of secundum atrial septal defects using Amplatzer device

OBJECTIVE

To evaluate the feasibility and short term results of transcatheter closure of secundum atrial septal defects (TCSASDs) using Amplatzer occluder device. A new self-centering device, the Amplatzer atrial septal occluder, has recently been evaluated in an animal model with excellent results. This paper reports our clinical research with this device.

METHODS

30 patients underwent an attempt at TCSASDs at an average age of 35.6 +/- 15.9 y (range, 5-62 y) and average weight of 63.6 +/- 14.5 kg (range, 17-78 kg) using the Amplatzer atrial septal occluder. The average ASD diameter measured by transesophageal echocardiography (TEE) was 23.6 +/- 4.0 mm (range, 16-31 mm), and the average atrial septal defects (ASD) balloon stretched diameter was 25.2 +/- 5.8 mm (range, 9-34 mm). All patients had right atrial and ventricular volume overload with a Qp/Qs of 3.4 +/- 1.2 (1.4-5.2). A F8-12 catheter was used for delivery of the device in all patients.

RESULTS

The device was placed correctly in all patients. There was immediate and complete closure in 30 patients. The average device waist size used to close the defect was 25.6 +/- 5.9 mm (range, 9-34 mm). There was no episode of device embolization or any other complication. Follow-up was performed using transthoracic echocardiography (TTE) 1 day, 1 month, 3 months, 6 months and 1 year after the procedure. The first day after operation; there was complete closure of the ASD in all patients; there have been no episodes of endocarditis, thromboembolism, or wire fracture.

CONCLUSION

TCSASDs using the Amplatzer occluder device was an efficient nonsurgical method which had a very high technical success rate and satisfactory short term and follow-up results.

Changes of reliability and efficiency of micronucleus bioassay in Vicia faba after exposure to metal contamination for several generations

Mitotic root micronucleus (MCN) frequency in Vicia faba as a bioassay, is primarily based on the extent of the sentinel Vicia response in terms of cytogenetic damage quantitatively or qualitatively to indicate the presence of mutagenic contaminants. This paper describes an investigation designed to assess changes in MCN frequencies of Vicia faba from three generation plants obtained, respectively from a reference site (RS) and a metal-contaminated experimental field (EF) in the bioassay of mutagenic Cd(2+) and NaN(3). The background value, dose-response to Cd(2+) and to NaN(3) in three generation (F(1), F(2) and F(3)) plants of the EF and the initial (F(0)) plants were determined in terms of MCN frequencies. With more generations of growing Vicia plants in the EF, a higher background value of MCN frequency, a lower slope value in the regression equation, a smaller ratio of MCN frequency between the control and treatment in the same generation and larger perturbation values were observed. This denotes that the decreased reliability and efficiency are represented in Vicia plants from the EF if the plants are used as sentinels in the bioassay of mutagenic Cd(2+) and NaN(3). It was concluded that the Vicia MCN bioassay should be used as an endpoint biomarker acceptable in biomonitoring environmental mutagens when the sentinel plants were collected from clean areas. Because no place is absolutely without pollutants, it is suggested that several seed stock centers should be established for providing sentinel Vicia if Vicia MCN bioassay is used as a biomarker to identify the global environmental status.

SEL-8, a nuclear protein required for LIN-12 and GLP-1 signaling in Caenorhabditis elegans

LIN-12 and GLP-1 are members of the LIN-12/Notch family of receptors that mediate cell-cell interactions during development. The sel-8 gene had been identified previously in a screen for suppressors of a mutation that constitutively activates LIN-12. Here, we report that sel-8 is essential for lin-12- and glp-1-mediated signaling, and that SEL-8 is a glutamine-rich nuclear protein. We postulate that SEL-8 serves as a transcriptional coactivator or as an assembly factor for transcription complexes that contain the LIN-12 or GLP-1 intracellular domains.

Haemodynamic mechanisms of corticotropin (ACTH)-induced hypertension in the rat

OBJECTIVES

To investigate the roles of cardiac output and systemic and regional resistances in corticotropin (ACTH)-induced hypertension in the rat

METHODS

This study consisted of three series of experiments with eight groups of male Sprague-Dawley rats (n = 132). Series 1 comprised groups 1-4, where group 1 = sham (0.9% NaCl, subcutaneous (s.c.) injection); group 2 = ACTH (0.5 mg/kg per day, s.c.); group 3 = atenolol + sham; group 4 = atenolol + ACTH treatments. Series 2 comprised groups 5 and 6, where group 5 = minoxidil + sham and group 6 = minoxidil + ACTH treatments. Series 3 comprised groups 7 and 8, where group 7 = ramipril + sham and group 8 = ramipril + ACTH treatments. Systolic blood pressure, water and food intakes, urine volume, and body weight were measured every second day. After 10 days of treatment, mean arterial blood pressure was measured by intra-arterial cannulation, and cardiac output (CO), and renal, mesenteric and hindquarter blood flows (RBF, MBF and HBF) determined using transonic small animal flowmeters.

RESULTS

ACTH treatment increased blood pressure (P < 0.001) with a rise in CO (P < 0.01) and renal vascular resistance (RVR, P < 0.05), but did not affect total peripheral resistance (TPR). Atenolol blocked the rise in CO without affecting the rise in blood pressure produced by ACTH treatment Minoxidil lowered TPR, but did not prevent the rise in blood pressure or renal vascular resistance. Ramipril blunted the rise in RVR and blood pressure without significantly affecting TPR.

CONCLUSION

Neither preventing rise in CO nor lowering TPR altered the ACTH-induced rise in blood pressure in the rat However, both the hypertension and rise in RVR were prevented by ramipril. These data suggest that increase in RVR may play a role in the pathogenesis of ACTH-induced hypertension in the rat.

p24 proteins and quality control of LIN-12 and GLP-1 trafficking in Caenorhabditis elegans

Mutations in the Caenorhabditis elegans sel-9 gene elevate the activity of lin-12 and glp-1, which encode members of the LIN-12/NOTCH family of receptors. Sequence analysis indicates SEL-9 is one of several C. elegans p24 proteins. Allele-specific genetic interactions suggest that reducing sel-9 activity increases the activity of mutations altering the extracellular domains of LIN-12 or GLP-1. Reducing sel-9 activity restores the trafficking to the plasma membrane of a mutant GLP-1 protein that would otherwise accumulate within the cell. Our results suggest a role for SEL-9 and other p24 proteins in the negative regulation of transport of LIN-12 and GLP-1 to the cell surface, and favor a role for p24 proteins in a quality control mechanism for endoplasmic reticulum-Golgi transport.

Detection of virtually all mutations-SSCP (DOVAM-S): a rapid method for mutation scanning with virtually 100% sensitivity

Dideoxy fingerprinting (ddF) was used as a tool to search for a generic set of conditions with sufficient power to detect virtually all mutations. For each condition tested, a very large sample of mutation-containing, single-stranded segments (about 1500) were analyzed with ddF. Correlation coefficients identified pairs of conditions in which single-strand conformation polymorphism (SSCP) mobilities were poorly correlated. The data strongly suggest that tertiary structure (e.g., base-sugar and sugar-sugar interactions) rather than secondary structure is the predominant determinant of mobility shifts by SSCP. Five conditions were selected with sufficient redundancy to detect all the mutations. The sensitivity of detection of virtually all mutations-SSCP (DOVAM-S) was determined by blinded analyses on samples containing additional mutations scattered throughout the eight exons and splice junctions in the factor IX gene. The factor IX gene sequence (2.5 kb) was scanned in one lane by 15 PCR-amplified segments (125 kb of sequence scanned per gel). All of the 84 single-base substitutions were detected in the blinded analyses, the first consisting of 50 hemizygous mutant and wild-type (WT) samples and the second consisting of 50 heterozygous mutant and WT samples. DOVAM-S is estimated to be five times faster than fluorescent DNA sequencing for the detection of virtually all mutations when the five conditions are applied.

Adrenocorticotrophin-induced hypertension: effects of mineralocorticoid and glucocorticoid receptor antagonism

OBJECTIVE

To examine whether the increase of blood pressure in adrenocorticotrophin-treated rats is mediated through mineralocorticoid or glucocorticoid receptors or corticosterone 6 beta-hydroxylation inhibition.

DESIGN

Rats were randomly allocated to 14 treatment groups for 10 days. The treatments included sham injection (n = 35), adrenocorticotrophin (5, 100, 500 micrograms/kg per day, subcutaneously, n = 5, 15 and 15, respectively), spironolactone (100 mg/kg per day, subcutaneously, n = 15), standard-dose or high-dose RU 486 (70 mg/kg every 3 days or 70 mg/kg per day, subcutaneously, n = 5 and 10, respectively), spironolactone + adrenocorticotrophin (100 micrograms/kg per day, n = 5, or 500 micrograms/kg per day, n = 10), standard-dose RU 486 + adrenocorticotrophin (500 micrograms/kg per day, n = 5), high-dose RU 486 + adrenocorticotrophin (100 micrograms/kg per day, n = 10), troleandomycin (40 mg/kg per day, subcutaneously, n = 5) and troleandomycin + adrenocorticotrophin (5 micrograms/kg per day, n = 5). Systolic blood pressure and metabolic parameters were measured every second day.

RESULTS

Adrenocorticotrophin treatment increased systolic blood pressure dose-dependently (5 micrograms/kg per day: +14 +/- 2 mmHg; 100 micrograms/kg per day: +20 +/- 2 mmHg; 500 micrograms/kg per day: +28 +/- 2 mmHg, all P < 0.001). Adrenocorticotrophin at 100 and 500 micrograms/kg per day increased plasma sodium and decreased plasma potassium concentrations. Spironolactone did not block adrenocorticotrophin-induced systolic blood pressure changes but did block changes in plasma sodium and potassium levels. Standard-dose RU 486 did not modify the adrenocorticotrophin-induced (500 micrograms/kg per day) systolic blood pressure rise but blocked the effect of adrenocorticotrophin on body weight. High-dose RU 486 partially blocked the adrenocorticotrophin-induced (100 micrograms/kg per day) systolic blood pressure increase (adrenocorticotrophin at 100 micrograms/kg per day: 143 +/- 3 mmHg; high-dose RU 486 + adrenocorticotrophin at 100 micrograms/kg per day: 128 +/- 5 mmHg, P < 0.001) and body-weight loss. Troleandomycin did not alter the development of adrenocorticotrophin-induced hypertension.

CONCLUSIONS

Spironolactone and standard-dose RU 486 did not modify adrenocorticotrophin-induced hypertension despite demonstrable antimineralocorticoid and antiglucocorticoid actions. High-dose RU 486 partially blocked adrenocorticotrophin-induced (100 micrograms/kg per day) hypertension, suggesting either a permissive effect of glucocorticoid on blood pressure or other antihypertensive actions of RU 486. Inhibition of glucocorticoid 6 beta-hydroxylation by troleandomycin did not modify adrenocorticotrophin-induced hypertension, suggesting that effects of corticosterone 6 beta-hydroxylation in adrenocorticotrophin-induced hypertension are negligible.

Post-therapy iodine-131 localization in unsuspected large renal cyst: possible mechanisms

Sensitive and specific, whole-body 131I scintigraphy remains an important technique for diagnosing metastases from differentiated papillary or follicular thyroid carcinoma. False-positive 131I localization is well recognized and can occur in a variety of conditions. We present a case of intense 131I localization in a previously unsuspected large renal cyst; the lesion was not visualized on routine preablation diagnostic 131I scintigraphy but was obvious on post-therapeutic whole-body imaging, underscoring the value of post-therapy imaging in detecting abnormalities not apparent on diagnostic studies. Radioiodine within the urinary bladder or, at times, the renal collecting system is expected, because 131I excretion is primarily by glomerular filtration. In the case presented here, 131I activity within the renal cyst supports the concept that iodide is subject to an active secretory process by the renal tubule.

Cartilage damaging activities of fibronectin fragments derived from cartilage and synovial fluid

OBJECTIVE

To investigate whether fibronectin fragments (Fn-fs), shown to damage cultured cartilage, can be found in cartilage from patients with osteoarthritis (OA) or rheumatoid arthritis, or can be generated from fibronectin (Fn) within synovial fluids or from Fn in the matrix of cultured cartilage. To also determine whether cartilage or synovial fluid Fn-fs are active and, thus, could contribute to cartilage damage in vivo.

METHODS

Fn-fs were immunochemically identified in cartilage extracts from patients with OA or rheumatoid arthritis or in bovine cartilage cultured with IL-1 alpha or in bovine synovial fluids treated with stromelysin-1 (MMP-3). The effect of removal of Fn-fs from OA synovial fluids was tested by passing fluids over an anti-Fn column and adding the resultant fluids to bovine cartilage cultures to measure proteoglycan (PG) degradation. Gelatin-Sepharose purified Fns from bovine plasma, synovial fluid or cartilage were digested with MMP-3 and the Fn-fs tested for degradation of PG in cultured cartilage.

RESULTS

Extracts of cartilage from patients with rheumatoid arthritis or with OA contained a range of Fn-fs. Removal of Fn-fs from OA synovial fluids significantly reduced the resultant damage when the fluids were added to cultured cartilage. Addition of IL-1 alpha to cultured cartilage or of MMP-3 to synovial fluids enhanced generation of Fn-fs. Fn-fs, whether derived from bovine plasma or synovial fluid or cartilage Fns, damaged cartilage.

CONCLUSIONS

These data demonstrate that although Fn-fs could be generated in vivo within synovial fluids and Fn-fs found in OA synovial fluid may contribute to cartilage damage in vivo, Fn-fs could also be generated within cartilage and amplify cartilage damage. Thus, Fn-fs may be both autocrine and paracrine regulators of cartilage metabolism.

Adrenocorticotrophin dose-response relationships in the rat: haemodynamic, metabolic and hormonal effects

OBJECTIVE

To determine adrenocorticotrophin dose-response relationships for increase of blood pressure and metabolic parameters of the Sprague-Dawley rat.

METHODS

We injected 120 male Sprague-Dawley rats twice daily subcutaneously for 10 days with 0.5, 1, 5, 50, 100, 200 or 500 microg/kg synthetic adrenocorticotrophin per day (all n = 10) or subjected them to sham injection (0.9% NaCl; n = 50). Systolic blood pressure, 24 h food intake, water intake, urine volume and body weight were measured. Data from a further 45 rats treated with 500 microg/kg per day adrenocorticotrophin in previous studies were included in the blood pressure analyses. After we had killed these rats, their organ weights (kidney, heart, adrenal) and plasma electrolyte, adrenocorticotrophin and serum corticosterone concentrations were measured.

RESULTS

On the final day of treatment systolic blood pressure of sham-injection control rats was 123 +/- 1 mmHg (n = 50). Compared with sham treatment, a low dose of adrenocorticotrophin (1 microg/kg per day) increased systolic blood pressure from 122 +/- 1 to 130 +/- 2 mmHg (P < 0.001) without any metabolic effects, whereas a high dose of adrenocorticotrophin (500 microg/kg per day) increased systolic blood pressure from 121 +/- 1 to 150 +/- 2 mmHg (P < 0.001, n = 55) with increases in intake of water and urine volume (P < 0.001, n = 10) and a decrease in body weight (P < 0.001, n = 10). Plasma adrenocorticotrophin and serum corticosterone concentrations for the sham-injection control group were 162 +/- 12 pg/ml (36 +/- 3 pmol/l) and 376 +/- 18 ng/ml (1038 +/- 50 nmol/l), respectively. Plasma adrenocorticotrophin concentration was elevated by injections of 100 (P < 0.05), 200 (P < 0.01) and 500 microg/kg adrenocorticotrophin per day (P = 0.001). Serum corticosterone concentration was not significantly different from that of sham-injection rats with 0.5-5 microg/kg adrenocorticotrophin per day but was increased by injection of 50-500 microg/kg adrenocorticotrophin per day (P < 0.001).

CONCLUSIONS

These results define 1 microg/kg adrenocorticotrophin per day, administered subcutaneously, as the threshold dose for causing a rise in blood pressure in the rat Thus administration of adrenocorticotrophin increases systolic blood pressure at doses that induce minimal adrenocorticotrophin metabolic effects. Administration of a low dose of adrenocorticotrophin to the rat is a suitable model for stress-induced hypertension.

Exposure of cartilage to a fibronectin fragment amplifies catabolic processes while also enhancing anabolic processes to limit damage

The addition of fibronectin fragments to cultured cartilage causes an initial suppression of proteoglycan synthesis, induction of matrix metalloproteinases, and resultant decrease in proteoglycan content by about 50% during the first few days in culture. Because the proteoglycan loss appears to be limited, we investigated whether the fibronectin fragments induce anabolic responses that might counter the damage. The effects of various lengths of exposure of cultured cartilage to the fibronectin fragment on proteoglycan content, proteoglycan synthesis rates, stromelysin-1 release, and tumor necrosis factor-alpha, interleukin-1alpha, and interleukin-6 release were investigated. The results showed that about 7 days of exposure of cultured cartilage to the fibronectin fragment was required for maximal cytokine release, proteoglycan depletion, and stromelysin-1 release. However, nearly maximal suppression of proteoglycan synthesis occurred within 1 day of the addition of the fibronectin fragment and, after its removal, the rates increased to supernormal levels. Decreasing exposure to 3 days caused only a small decrease in cartilage proteoglycan content, although stromelysin-1 release still occurred. Decreasing exposure to 1 day caused an immediate increase in proteoglycan synthesis and an increase to supernormal proteoglycan contents. The effect of first treating cartilage with the fibronectin fragment for various periods and then allowing a recovery was to make the cartilage more resistant to secondary exposures. This study shows that cartilage damage can be caused by short exposures to the fibronectin fragment and that exposures either optimal or suboptimal for damage additionally amplify anabolic processes to make the cartilage resistant to further damage and, thus, condition it against pending amplification of damage.

Hemodynamic profile of corticotropin-induced hypertension in the rat

OBJECTIVES

To examine hemodynamic variables in corticotropin-induced hypertension in rats and the effects of reversal of the hypertension by L-arginine on the hemodynamic profile.

METHODS

Sixty male Sprague-Dawley rats were randomly divided into four groups: sham treatment (0.9% NaCl, injected subcutaneously); 0.5 mg/kg corticotropin per day, subcutaneously; 0.6% L-arginine in food plus sham; and L-arginine plus corticotropin. Systolic blood pressure, water and food intakes, urine volume, and body weight were measured every second day. After 10 days mean arterial blood pressure was measured by intra-arterial cannulation, and cardiac output, and renal, mesenteric, and hindquarter blood flows were determined using transonic small animal flowmeters.

RESULTS

Injection of corticotropin increased blood pressure, water intake, urine volume, and plasma sodium concentration, and decreased body weight and plasma potassium concentration. It increased cardiac output (P < 0.01), mesenteric blood flow (P < 0.05), and renal vascular resistance (P < 0.05), and decreased renal blood flow (P < 0.05), but did not change calculated total peripheral resistance, hindquarter blood flow, mesenteric or hindquarter vascular resistance. L-arginine prevented corticotropin-induced rises in blood pressure (P < 0.001) and renal vascular resistance (P < 0.05), and a fall in renal blood flow (P < 0.05), but did not affect other hemodynamic variables.

CONCLUSION

The hemodynamic profile of corticotropin-induced hypertension in the rat is characterized by a rise in cardiac output and renal vascular resistance, a fall in renal blood flow, but no change in total peripheral resistance, hindquarter blood flow, mesenteric vascular resistance, or hindquarter vascular resistance. L-arginine prevented corticotropin-induced rises both in blood pressure and in renal vascular resistance in the rat. These data suggest that the increase in renal vascular resistance might play a role in corticotropin-induced hypertension in the rat.

SUP-17, a Caenorhabditis elegans ADAM protein related to Drosophila KUZBANIAN, and its role in LIN-12/NOTCH signalling

LIN-12/NOTCH proteins mediate cell-cell interactions that specify cell fates. Previous work suggested that sup-17 facilitates lin-12 signalling in Caenorhabditis elegans. Here, we show that sup-17 encodes a member of the ADAM family of metalloproteases. SUP-17 is highly similar to Drosophila KUZBANIAN, which functions in Drosophila neurogenesis, and the vertebrate ADAM10 protein. Furthermore, we show by genetic analysis that the extracellular domain of LIN-12 appears to be necessary for sup-17 to facilitate lin-12 signalling and that sup-17 does not act downstream of lin-12. Finally, we show by cell ablation experiments that sup-17 can act cell autonomously to facilitate lin-12 activity. We discuss the implications of our observations for LIN-12/NOTCH signalling and how our results complement and extend results obtained from genetic analysis of kuz in Drosophila.

Agents that block fibronectin fragment-mediated cartilage damage also promote repair

OBJECTIVE AND DESIGN

The objective was to determine if agents that suppress catabolism might also enhance repair of irreversibly damaged cartilage.

MATERIAL

Articular cartilage from bovine metacarpophalangeal joints was studied in explant culture.

TREATMENT

Fibronectin fragments or IL-1 alpha, which potently cause proteoglycan (PG) loss from cartilage, were added to cultures also containing the catabolism-blocking agents: insulin-like growth factor-1, or N-acetylcysteine, or Arg-Gly-Asp-Ser peptide, and the effects of these agents on blocking PG loss determined. To test for repair or restoration of PG, cartilage was first damaged, damage agents removed and inhibitory agents added.

METHODS

Each mean and SD value for cartilage PG content was determined by assays of papain digests of cartilage from three similar cultures.

RESULTS

The agents either partially or fully blocked PG loss and promoted repair.

CONCLUSIONS

Normally irreversible cartilage damage was reversed by slowing ongoing catabolic processes during attempted repair. Thus, catabolic inhibitors have reparative potential.

Hypotensive effects of peptide T in conscious rats

1. The present study investigated the effects of peptide T on mean arterial blood pressure (MAP) in conscious normotensive Sprague-Dawley (SD) rats, spontaneously hypertensive rats (SHR) and two-kidney one-clip (2K1C) hypertensive rats. 2. Peptide T was infused via the left jugular vein at a rate of 1 mg/kg per h in SD, SHR and 2K1C rats and then at doses of 0.1, 0.25, 0.5, 1 and 5 mg/kg per h in SHR, with 0.9% saline as a sham control in SHR and 2K1C. Mean arterial pressure was measured directly before, during and after infusion. 3. Peptide T (1 mg/kg per h) decreased blood pressure in both SHR (P < 0.01) and 2K1C (P < 0.05). In normotensive SD rats the fall in MAP approached statistical significance (P = 0.06). The effect of peptide T was not significantly different in normotensive compared with hypertensive rats. Saline infusion had no effect. The blood pressure lowering effect of peptide T appeared to be dose-dependent in SHR.

Hyaluronic acid suppresses fibronectin fragment mediated cartilage chondrolysis: I. In vitro

A commercial preparation of 800-kDa hyaluronic acid (HA), (ARTZ from Seikagaku, Inc.), has been used as a therapeutic intervention in the treatment of osteoarthritis (OA). We tested the effect of this HA form, HA/800, in an in vitro cartilage chondrolytic system in which a specific amino-terminal 29-kDa fragment of fibronectin (Fn-f) penetrates cartilage tissue to activate chondrocytes to amplify two major chondrolytic activities: suppression of proteoglycan (PG) synthesis and induction of matrix metalloproteinases. We report that HA/800 did not block damage by Fn-f in serum free cartilage cultures. However, HA/800 was effective in blocking the ability of 100 nM Fn-f to cause the degradation and release of half of the total cartilage PG from cartilage in 10% serum/DMEM cultures. While the Fn-f caused a half-time for PG release of 3 days, continuous exposure to 0.1 or 1 mg/ml HA/800 slowed the half-time to 12 days. Further, a single 1 day pre-incubation with 0.1 or 1 mg/ml HA/800 was sufficient to decrease the half-time of 100 nM Fn-f mediated PG depletion to 7 and 12 days, respectively. HA/800 completely blocked the effect of 10 nM Fn-f. Blocking of Fn-f-mediated cartilage PG depletion was associated with a decreased concentration of Fn-f on the superficial cartilage surface and decreased penetration into the cultured cartilage tissue. Further, the two major chondrolytic activities of the Fn-f, suppression of synthesis of PG and enhanced release of stromelysin-1, were suppressed by HA/800. HA/800 also partially restored PG in cartilage first damaged with the Fn-F. We conclude that HA/800 slows Fn-f-mediated cartilage chondrolysis in vitro and has some reparative potential. The damage blocking activity appears to be associated with the ability of HA/800 to block penetration of the Fn-f, rather than with direct effects on cartilage tissue.

Hyaluronic acid suppresses fibronectin fragment mediated cartilage chondrolysis: II. In vivo

Intra-articular sodium hyaluronic acid (HA) has been used as a treatment intervention in the management of osteoarthritis. It has been observed that HA can coat the articular surface, and thus, has been suggested to provide a possible prophylactic barrier for the articular cartilage. In an accompanying manuscript (Homandberg et al.), we report that a commercially available high-molecular-weight HA (approximately 800-kDa, ARTZ, Seikagaku Corp.) can partially block fibronectin fragment (Fn-f)-mediated cartilage injury in vitro. Herein we report a study of the effects of intra-articular HA on an in vivo animal model of Fn-f-mediated cartilage injury. Rabbit knees were injected with Fn-f, and after 1 week, the cartilage proteoglycan (PG) content had decreased to 59 +/- 8% of control. In sharp contrast, PG content in knees receiving pre-treatment with HA followed by Fn-f injection had only decreased to 85 +/- 27% of control (P < 0.01). Similarly, the PG content in knees receiving an injection of Fn-f, followed by an injection of HA were significantly higher (74 +/- 18% of control) than Fn-f injured knees with no treatment (P < 0.02). Intra-articular HA alone had no effect on cartilage PG content. The results in this study suggest that HA is effective in partially preventing Fn-f mediated cartilage injury, most likely by coating the articular surface. Further, HA treatment after Fn-f injury may facilitate restoration of matrix components.

[Clinical analysis of 7 cases of mesenteric venous thrombosis]

7 patients with mesenteric venous thrombosis (MVT) were treated in Anzhen Hospital from 1984 to 1996. The patients were all operated on and the diagnosis was confirmed pathologically. Fine patients were cured and 2 died. We discussed the pathophsiology, pathogeny, clinical manifestation, diagnosis and treatment of MVT. Most of the patients presented with a clinical picture of acute abdomen and the diagnosis was made only at laparotomy. Close observation and proper laparotomy should be given to the doubtful cases. To reduce the mortality rate of MVT, we resected the bowel which looks normal in appearance but comprises the mesentery of thrombosis. Adequate anticoagulant therapy should be given as early as possible.