[Experimental study on the osteoradionerosis of jaw model of dogs with vascular corrosion casting]

OBJECTIVE

To study pathologic alterations of mandibular microvascular system in osteoradionecrosis of jaws (ORNJ) in order to disclose its pathologic mechanism.

METHODS

The right maxillofacial regions of 10 dogs were exposed to cobalt-60 radiation with a total dose of 60-80 Gy and dental extraction were performed at 3, 6 months after radiation. The ORNJ was diagnosed by gross observation, X-ray film and histopathologic examination. Then, the vascular corrosion castings of jaws were implemented and investigated.

RESULTS

At 12 months after radiation, 7 cases of ORNJ occured. It was discovered on the casting specimen that the continuity of inferior alveolar arteries remained intact except one case where the artery was obliterated due to lesion involvement. There were defects of vascular networks in the necrotic area with irregular capillaries proliferating in the periphery of lesions and around the inferior alveolar arteries, where x-ray examination showed new bone formation.

CONCLUSION

Based on the experimental evidences, a new concept of pathogenesis of ORNJ is put forward: following the formation of "3-hypo" structures, local trauma-repairing process might induce capillary proliferation which bring about a large amount of mitotic death of endotheliocytes, the microcirculation failure takes place leading to ORNJ eventually.

Stimulation of type I collagen transcription in human skin fibroblasts by TGF-beta: involvement of Smad 3

Transforming growth factor-beta (TGF-beta) stimulates the transcription of the alpha2(I) procollagen gene (COL1A2). The intracellular mediators involved in this response remain poorly understood. In this study, we demonstrate that primary human skin fibroblasts express Smads, a novel family of signaling molecules, in vitro in the absence of TGF-beta. The levels of Smad 7 mRNA was rapidly and transiently increased by TGF-beta. Transient overexpression of Smad 3 and Smad 4, but not Smad 1 or Smad 2, caused trans-activation of a CAT reporter gene driven by a 772 bp segment of the human COL1A2 promoter containing putative TGF-beta response elements. Smad stimulation of promoter activity was ligand independent, but was further enhanced by TGF-beta. Overexpression of a phosphorylation-deficient Smad 3 mutant or wild-type Smad 7, which lacks the carboxy-terminal phosphorylation motif, specifically inhibited TGF-beta-induced activation of COL1A2 promoter. A CAGACA sequence shown to be a functional Smad-binding element in the plasminogen activator inhibitor-1 gene promoter was found within the TGF-beta-response region of the proximal COL1A2 promoter. Gel mobility shift assays showed protein phosphorylation-dependent binding activity in fibroblast nuclear extracts specific for this sequence; TGF-beta treatment strongly stimulated the formation of this DNA-protein complex. Smad was identified as a component of the CAGACA-binding transcription complex in TGF-beta-treated fibroblasts by antibody supershifting. These results demonstrate that (i) Smad 3 transmits TGF-beta signals from the receptor to the COL1A2 promoter in human fibroblasts, and is likely to play an important role in stimulation of COL1A2 promoter activity elicited by TGF-beta; (ii) in fibroblasts, Smads appear to function as inducible DNA-binding transcription factors; and (iii) Smad 7 may be involved in autocrine negative feedback in the regulation of COL1A2 promoter activity by TGF-beta.

[Diagnosis and treatment of tethered cord syndrome in adults]

OBJECTIVE

To study the clinical characteristics of tethered cord syndrome (TCS) in adults.

METHOD

18 patients with TCS were confirmed by preoperative MRI and were operated on for releasing of tethered conus. Pathological mechanism and main points of operation were analysed according to the operative findings and radiological data.

RESULT

The cord or conus were tethered by intradural tumors (6 patients), myelomeningocele (6), thickened filum terminale (3), diastematomyelia (2) and adhesion after operation (1). 14 of the 18 patients showed good results after follow-up for 8 months to 5 years.

CONCLUSION

Clinical manifestation and prognosis of TCS in adults are different from those of TCS in children. Attention should be paid to avoid additional injury to the conus and cauda equina during operation. The long course of disease and retethering of the conus lead to poor outcome.

[Clinical significance of early diagnosis of cervical spondylotic myelopathy]

OBJECTIVE

To probe into the possibility of early diagnosis of cervical spondylotic myelopathy (CSM) prospectively and to screen the premorbid signs of CSM clinically, radiologically and electro-physiologically.

METHOD

Twenty-nine items related to the occurring of CSM were chosen as common characteristics of CSM and considered as the criteria of prospective study. 81 patients who met the criteria were studied. All patients were followed up and observed for 2 - 6.5 years (mean 3.7 years).

RESULT

Twenty-nine patients showed CSM during investigation. Thirteen items of the criteria were related to the occurring of CSM. The significant items include upper limb pain and abnormal sensation limb numbness, positive dynamic Hoffmann's sign, cervical canal stenosis, lower cervical instability, cervical intervertebral disc herniation, and delay of central motor conduct time.

CONCLUSION

CSM can be early diagnosed. The patients who meet the established criteria should be followed up and observed closely. Early operation results in good effect.

Evidence that NMDA receptors mediate the responses of putative RVLM presympathetic neurons to vagal afferent stimulation in rats

Experiments were performed in 25 urethane-anaesthetized male Sprague-Dawley rats. Forty-six RVLM neurons were identified as putative presympathetic neurons according to their arterial baroreceptor reflex related properties, i.e. they were inhibited by stimulation of the aortic nerve; silenced by elevation of blood pressure and had a cardiac cycle related rhythm of spontaneous discharge. Responses of these neurons to tripled square wave stimulation of vagal afferents was tested by means of peristimulus time histograms. In addition to a long-lasting inhibition (I2), some neurons had one (P0) or two excitatory peaks (P1 and P2), and there was a short-lasting inhibition (I1) between P1 and P2. After microinjection of CPP (0.1 microl, 50 mM) into the NTS, the inhibitory responses were blocked, but the excitatory peaks were not affected; in the CVLM, CPP microinjection of the same dose had a similar effect on the responses elicited by vagal afferent stimulation in 15 of the 24 neurons tested. No detectable effects were observed in 9 neurons. However, intravenously administered ketamine attenuated or abolished these responses, either inhibitory or excitatory, in a dose dependent way. These results suggest: (1) an NMDA mechanism is involved in both the inhibitory and the excitatory responses. For the inhibitory responses, the involvement is both in the NTS and in the CVLM; for the excitatory responses, it is probably in the RVLM. (2) There may be a direct excitatory amino acid (EAA) pathway from the NTS to the RVLM.

The efficacy of safety policies on traffic fatalities in Singapore

This paper uses regression models to investigate the efficacy of the seat belt regulation as well as the circuit training and testing system in reducing traffic related fatalities in Singapore. The effectiveness of alcohol breathalysers was also studied. Results suggest that the seat belt regulation does not have any impact on traffic fatalities. The use of breathalysers was found to be effective in reducing occupant fatalities. The circuit training and testing system, which aims to equip new pools of motorists with appropriate driving or riding skills, was found to be effective in reducing non-occupant fatalities and total fatalities.

Modulation of cellular tryptophan metabolism in human fibroblasts by transforming growth factor-beta: selective inhibition of indoleamine 2,3-dioxygenase and tryptophanyl-tRNA synthetase gene expression

Alterations in the rate of cellular tryptophan metabolism are involved in mediating important biological activities associated with cytokines and growth factors. Indoleamine 2,3-dioxygenase (IDO) and tryptophanyl-tRNA synthetase are enzymes of tryptophan metabolism whose expression in a variety of cells and tissues is highly inducible by interferon-gamma (IFN-gamma). Transforming growth factor-beta (TGF-beta) antagonizes many cellular responses to IFN-gamma. The interaction of these two cytokines plays an important role in maintaining homeostasis during inflammation and repair. In human skin and synovial fibroblasts in vitro, TGF-beta caused time- and dose-dependent abrogation of IFN-gamma-stimulated expression of IDO and tryptophanyl-tRNA synthetase mRNAs. The inhibition was selective and did not appear to be due to down-regulation of IFN-gamma signaling by TGF-beta. In parallel with its effect on IDO mRNA expression, TGF-beta caused a marked reduction in intracellular IDO protein levels and abrogated IDO activity and tryptophan catabolism in these cells induced by IFN-gamma. IFN-gamma caused a rapid and striking increase in the amount of IDO heterogeneous nuclear pre-mRNA and induced transcription of the IDO gene, as demonstrated by transient transfection assays. TGF-beta partially reversed this stimulation. IFN regulatory factor (IRF)-1 and stat1 are cellular intermediates in IFN signaling. Both are implicated in activation of IDO transcription in response to IFN-gamma. The stimulation by IFN-gamma of IRF-1 protein and mRNA expression was not prevented by treatment of fibroblasts with TGF-beta. Furthermore, gel mobility shift assays indicated that TGF-beta did not inhibit the induction of stat1 and IRF-1 binding activity to their cognate DNA recognition sites in the IDO gene promoter. In contrast, the stability of IDO mRNA transcripts was reduced in fibroblasts treated with TGF-beta, as shown by determination of mRNA half-lives following blockade of transcription with 5,6-dichlorobenzimidazole riboside. The findings indicate that TGF-beta prevents the induction of IDO and tryptophanyl-tRNA synthetase gene expression in fibroblasts. The repression of IDO expression by TGF-beta is mediated at both transcriptional and posttranscriptional levels. These results implicate TGF-beta in the negative regulation of tryptophan metabolism, provide evidence for the molecular basis of this regulation, and indicate that cellular tryptophan metabolism is under tight immunological control.

Modulation of cellular tryptophan metabolism in human fibroblasts by transforming growth factor-beta: selective inhibition of indoleamine 2,3-dioxygenase and tryptophanyl-tRNA synthetase gene expression

Alterations in the rate of cellular tryptophan metabolism are involved in mediating important biological activities associated with cytokines and growth factors. Indoleamine 2,3-dioxygenase (IDO) and tryptophanyl-tRNA synthetase are enzymes of tryptophan metabolism whose expression in a variety of cells and tissues is highly inducible by interferon-gamma (IFN-gamma). Transforming growth factor-beta (TGF-beta) antagonizes many cellular responses to IFN-gamma. The interaction of these two cytokines plays an important role in maintaining homeostasis during inflammation and repair. In human skin and synovial fibroblasts in vitro, TGF-beta caused time- and dose-dependent abrogation of IFN-gamma-stimulated expression of IDO and tryptophanyl-tRNA synthetase mRNAs. The inhibition was selective and did not appear to be due to down-regulation of IFN-gamma signaling by TGF-beta. In parallel with its effect on IDO mRNA expression, TGF-beta caused a marked reduction in intracellular IDO protein levels and abrogated IDO activity and tryptophan catabolism in these cells induced by IFN-gamma. IFN-gamma caused a rapid and striking increase in the amount of IDO heterogeneous nuclear pre-mRNA and induced transcription of the IDO gene, as demonstrated by transient transfection assays. TGF-beta partially reversed this stimulation. IFN regulatory factor (IRF)-1 and stat1 are cellular intermediates in IFN signaling. Both are implicated in activation of IDO transcription in response to IFN-gamma. The stimulation by IFN-gamma of IRF-1 protein and mRNA expression was not prevented by treatment of fibroblasts with TGF-beta. Furthermore, gel mobility shift assays indicated that TGF-beta did not inhibit the induction of stat1 and IRF-1 binding activity to their cognate DNA recognition sites in the IDO gene promoter. In contrast, the stability of IDO mRNA transcripts was reduced in fibroblasts treated with TGF-beta, as shown by determination of mRNA half-lives following blockade of transcription with 5,6-dichlorobenzimidazole riboside. The findings indicate that TGF-beta prevents the induction of IDO and tryptophanyl-tRNA synthetase gene expression in fibroblasts. The repression of IDO expression by TGF-beta is mediated at both transcriptional and posttranscriptional levels. These results implicate TGF-beta in the negative regulation of tryptophan metabolism, provide evidence for the molecular basis of this regulation, and indicate that cellular tryptophan metabolism is under tight immunological control.

Radiculopathy after laminectomy for cervical compression myelopathy

Postoperative radiculopathy is a complication of posterior cervical decompression associated with tethering of the nerve root. We reviewed retrospectively 287 consecutive patients with cervical compression myelopathy who had been treated by multilevel cervical laminectomy and identified 37 (12.9%) with postoperative radiculopathy. There were 27 men and ten women with a mean age of 56 years at the time of operation. The diagnosis was either cervical spondylosis (25 patients) or ossification of the posterior longitudinal ligament (12 patients).

Radiculopathy was observed from four hours to six days after surgery. The most frequent pattern of paralysis was involvement of the C5 and C6 roots of the motor-dominant type. The mean time for recovery was 5.4 months (two weeks to three years). The results at follow-up showed that the rate of motor recovery was negatively related to the duration of complete recovery of postoperative radiculopathy (γ = −0.832, p < 0.01) and that patients with spondylotic myelopathy had a significantly better rate of clinical recovery than those with ossification of the posterior longitudinal ligament (t = 2.960, p < 0.01).

Postoperative radiculopathy may be prevented by carrying out an anterior decompression in conjunction with spinal fusion, which will achieve stabilisation and directly remove compression of the cord at multiple levels.

Radiculopathy after laminectomy for cervical compression myelopathy

Postoperative radiculopathy is a complication of posterior cervical decompression associated with tethering of the nerve root. We reviewed retrospectively 287 consecutive patients with cervical compression myelopathy who had been treated by multilevel cervical laminectomy and identified 37 (12.9%) with postoperative radiculopathy. There were 27 men and ten women with a mean age of 56 years at the time of operation. The diagnosis was either cervical spondylosis (25 patients) or ossification of the posterior longitudinal ligament (12 patients). Radiculopathy was observed from four hours to six days after surgery. The most frequent pattern of paralysis was involvement of the C5 and C6 roots of the motor-dominant type. The mean time for recovery was 5.4 months (two weeks to three years). The results at follow-up showed that the rate of motor recovery was negatively related to the duration of complete recovery of postoperative radiculopathy (gamma=-0.832, p < 0.01) and that patients with spondylotic myelopathy had a significantly better rate of clinical recovery than those with ossification of the posterior longitudinal ligament (t=2.960, p < 0.01). Postoperative radiculopathy may be prevented by carrying out an anterior decompression in conjunction with spinal fusion, which will achieve stabilisation and directly remove compression of the cord at multiple levels.

Application of a new serum assay for type I collagen cross-linked N-telopeptides: assessment of diurnal changes in bone turnover with and without alendronate treatment

Biochemical markers of bone turnover are finding increased application in the investigation and management of skeletal diseases such as osteoporosis. The present study assessed for the first time the diurnal variation of serum type I collagen cross-linked N-telopeptides (NTx), a new serum-based marker of bone resorption, and the effect of antiresorptive therapy with alendronate on this marker in elderly osteopenic women. The concentrations of serum NTx were monitored over 24 hours in a randomly selected subset of 38 women (placebo n = 13, 69 +/- 3 (SD) year; alendronate n = 25, 69 +/- 3 year), who had completed 12-15 months of a larger (n = 120) randomized, double-blind, parallel group, placebo-controlled trial with alendronate 5 mg/day. Blood was obtained every 4 hours for measurement of serum NTx using a new chemiluminescent-based immunoassay. There was a significant diurnal variation of serum NTx (p = 0.001) in both the placebo and alendronate groups. Mean peak levels occurred at approximately 0504 h with a mean nadir at approximately 1320 h in the placebo group, with no significant difference on alendronate. Serum NTx was approximately 25% lower in the alendronate group over the entire 24-hour period. Mean (SE) daytime (0800-2000) and nighttime (2200-0800) serum NTx values were 6.40 +/- 0.30 versus 8.45 +/- 0.58 nmol BCE/liter, and 7.42 +/- 0.23 versus 10.01 +/- 0.53 nmol BCE/liter for alendronate versus placebo, respectively (P < or = 0.003 for both comparisons). Combining the data of both treatment groups, serum NTx was significantly (P < 0.05) correlated with serum osteocalcin (r = 0.753) and urine NTx (r = 0.628) measurements previously obtained over the entire 24-hour period. Serum NTx has a significant diurnal variation and is responsive to antiresorptive therapy with alendronate. Alendronate reduces the amplitude but maintains the pattern of the 24-hour serum NTx profile. These data suggest that serum NTx may be a useful new marker of bone resorption.

[The effects of graded spinal cord injuries on transcranial electric stimulation motor evoked potentials in the rat]

OBJECTIVE

To study the effects of graded spinal cord injury (SCI) on the motor evoked potentials (MEP) characteristics and the prognostic value of MEP for the motor function.

METHOD

Modified Allen's method was used by weight drop force of 30 gcf, 50 gcf, 80 gcf and 100 gcf on the T(8 - 9) spinal cord of 40 SD rats in order to make SCI models. MEP was recorded continuously at L(1 - 2) epidurally and bilateral gastrocnemius muscles before and after the spinal cord lesion was produced (followed up for 1 month). The inclined plane and Tarlov technique were used to assess clinical neurological function.

RESULT

The amplitude of rat's MEP changed significantly with graded SCI, the more sever the lesion, the lower the potentials. mMEP was more sensitive than scMEP, though the abolishment of mMEP soon after SCI didn't indicate that the animals could not regain ambulation. Changes in amplitude of scMEP recorded early after SCI were collaborate significantly with inclined plane (gamma = 0.9665, P < 0.01) and Tarlov scale (gamma = 0.8893, P < 0.01) assessed 1 month later, and can be used as a chronic measure parameter of motor function prognosis. scMEP still existed 1 month after SCI in 3 of 11 rats (27.3%) without any voluntary movement in bilateral hindlimbs, suggesting that some parts of conductive function still existed in the spinal cord. So it should be called "discomplete SCI".

CONCLUSIONS

scMEP can be used as a reliable parameter for motor function prognosis, because it reflects objectively and sensitively the severity of central motor neurol fiber injury.

Discovery of a novel series of potent and selective substrate-based inhibitors of p60c-src protein tyrosine kinase: conformational and topographical constraints in peptide design

On the basis of the efficient substrate for p60c-src protein tyrosine kinase (PTK) YIYGSFK-NH2 (1) (Km = 55 microM) obtained by combinatorial methods, we have designed and synthesized a series of conformationally and topographically constrained substrate-based peptide inhibitors of this enzyme, which showed IC50 values in the low-micromolar range (1-3 microM). A "rotamer scan" was performed by introducing the four stereoisomers of beta-Me(2')Nal in the postulated interaction site of the peptide inhibitor 23(IC50 = 1.6 microM). This substitution led to selective and potent inhibitors of p60c-src PTK; however, no substantial difference in potency was observed among them. This and the results of the "stereochemical scan" performed at residues 2 and 7 of 3 (peptides 19-21), which form the disulfide bond, may suggest that the enzyme active site does not have rigid topographic requirements and thus is able to achieve important conformational changes to bind the ligand as long as the pharmacophore pattern in the inhibitor is conserved. Two new potent iodo-containing nonphosphorylatable tyrosine analogues were also incorporated into our lead inhibitory sequence 23, producing the most potent inhibitors for p60c-src PTK identified thus far in our studies. Compounds 29 and 30 exhibit IC50 values of 0.13 and 0.54 microM, respectively. Peptide 29 is 420-fold more potent than the parent peptide 1. Selectivity studies of peptides 23-30 toward p60c-src, Lyn, and Lck PTK showed in general high Lyn/Src and moderate Lck/Src selectivity ratios. We found that the chi1 space constraints of the specialized amino acids, introduced at position 3 of the peptide lead 23, were not as important as the configuration of the Calpha of that residue to recognize the subtle chemical environment surrounding the active site of Src and Lck PTK, as reflected on the obtained Lck/Src selectivity ratios.

Glutathione transferase T1 and M1 genotype polymorphism in the normal population of Shanghai

Glutathione transferases are known to be important enzymes in the metabolism of xenobiotics. In humans genetic polymorphisms have been reported for the hGSTM1 and hGSTT1 genes leading to individual differences in susceptibility towards toxic effects, such as cancer. This study describes the distribution of the two polymorphisms of hGSTT1 and hGSTM1 in the normal Chinese population of Shanghai. Out of 219 healthy individuals having been genotyped for GSTT1 and GSTM1, 108 (49%) were identified to be homozygously deficient for the GSTT1 gene and 107 (49%) for the GSTM1 gene.

[Study of physiological parameters of velopharyngeal function by nasopharyngeal fibroscope]

OBJECTIVE

Velopharyngeal incompetency (VPI) could be found in certain healthy people when some vowels were produced. Since neither asophia nor organic deformity do they have, it should be considered as physiological VPI. VPI which exists commonly in patients with cleft palate is also an unsatisfactory manifestation after palatoplasty. In order to distinguish between physiological VPI and pathological VPI in patient with cleft palate and establish an objective criterion, it is necessary to assess the occurrence and extent of VPI in healthy people.

METHODS

The velopharyngeal function of 890 subjects with normal speech was studied dynamically by nasopharyngeal fiberscope (NPF). Two vowels /i/ and /u/ were examined. The rates of velopharyngeal incompetence (RVPI) of vowel /i/ and /u/ were analyzed.

RESULTS

VPI was found in 117 (13.15%) when vowel /i/ was produced. VPI was occurred in 100 (11.24%) when /u/ was produced. The RVPI mean of vowel /i/ is 11.285% +/- 7.248 in 112 subjects, while that of /u/ is 9.066% +/- 6.162 in 96. No significant difference was obtained in age or sex.

CONCLUSION

It can be used to evaluate the velopharyngeal function after palatoplasty as physiological parameters.

[Quantitative analysis of velopharyngeal function by nasopharyngeal fibroscope (NPF)]

OBJECTIVE

To estimate the reliability of the nasopharyngeal fibroscope (NPF) for assessing velopharyngeal function.

METHODS

16 well-pronounced males were examined by NPF which was positioned in different depth. Same procedures were repeated after a week.

RESULTS

The results indicated that the rate of velopharyngeal incomptence (RVPI) of NPF had no significant difference when checked in different time and various depths.

CONCLUSION

RVPI can be used as a parameter of quantitative analysis for velopharyngeal function, and our results suggested that it is reliable and reproduciable.

[Cervical spondylotic myelopathy: early diagnosis and timing of operation]

OBJECTIVES

To study early clinical characteristics and diagnosis of cervical spondylotic myelopathy and to search the timing of surgery.

METHOD

Seventy-four cases of early diagnosed cervical spondylotic myelopathy (CSM) were treated with anterior cervical decompression and autologous ilium graft fusion.

RESULT

The early stage of CSM was indistinct, and symptoms were mild. Neck pain, abnormality of motion and sensation of limbs, and hand and arm symptoms were shown frequently. Changes in neurological function could found during physical examination. Characteristic changes in imaging were helpful in early diagnosis of the disease.

CONCLUSION

Early diagnosis and surgery of CSM are important in improving the therapeutic results.

Diagnosis and treatment of acute central cervical cord injury

OBJECTIVE

To clarify the diagnosis and management of acute central cervical cord injury.

METHODS

Eighty-nine patients with acute cervical central cord injury were retrospectively reviewed. Sixty-three patients were treated conservatively and 26 were treated surgically. There were two acute deaths. Eighty-seven patients were followed up for 3 months to 15 years.

RESULTS

Their average neurological score (ASIA) was increased from 41.7 at admission to 83.1 at follow-up.

CONCLUSIONS

Acute central cervical cord injury should be differentiated from complete spinal cord injury, cervical myelopathy, cruciate paralysis and C8 nerve root injury. When compression of nerve tissue or cervical instability is identified, operative intervention should be indicated. The prognosis is less optimistic in the patients with severe primary injury and at old age.

Evidence for separate control of slow version and vergence eye movements: support for Hering's Law

When a visual stimulus changes direction and distance simultaneously, Hering's Law argues that the resulting eye movements are the result of combined version and vergence control processes. Recently, it has been suggested that slow asymmetrical eye movements might be guided by monocular control processes wherein each eye is driven by its own retinal image. Experimental results presented here show behavioral differences between slow version and slow vergence eye movements, indicating that different control processes drive the two "pure" responses. Specifically, version tracking of constant velocity stimuli (i.e., smooth pursuit) is more precise, showing less variation in tracking velocity than movements of equal velocity produced by vergence stimuli. When the two stimuli are combined, the variability in tracking is consistent with the addition of the two components in proportion to their respective stimuli. These results provide support for Hering's Law, at least for low velocity, smooth tracking movements (i.e., slow version and slow vergence.

[Experimental study of radiation effects on the mandibular microvasculature of the guinea-pigs]

In the experiment, both 180 kV X-ray and cobalt-60 radiation were delivered to right mandibles of 128 guinea-pigs with different dose (1000 cGy x 4, 800 cGy x 4, 600 cGy x 4, 400 cGy x 4 within 1 week). Dental extractions were conducted 1, 3, 5 months after radiation and the irradiated animals were examined by using microvascular corrosion castings of mandibles. It was found that the number of capillaries reduced and microvascular networks broke off after radiation with small veins shrinking subsequently while the alterations of arteries were slight. This result indicated that capillary was the most vulnerable part to the damage of radiation in the vascular system. In addition the defects of vascular networks around the non-healing tooth extraction sites were also discovered with irregularly capillary proliferation in the periphery of the lesion. The phenomena suggested that microcirculation failure induced by trauma-repairing process lead to occurRence of osteoradionecrosis of jaws.

Nonstructural protein-2 and the replication of canine parvovirus

The nonstructural protein-2 (NS2) of canine parvovirus (CPV) is produced from the left-hand open reading frame of the viral genome and contains 87 amino-terminal amino acids in common with nonstructural protein 1 (NS1) joined to 78 amino acids from an alternative open reading frame. In the minute virus of mice parvovirus NS2 plays a role in controlling capsid protein assembly and translation in a host-specific manner. The predicted NS2 of CPV is divergent from the proteins of the rodent parvoviruses, and the protein and its functions have not been described. We characterized the large and the small splices of CPV using reverse transcriptase-PCR, NS2 was identified using anti-peptide antibodies against the predicted C-terminal sequence and also by expressing the protein from a plasmid vector. The protein could be detected at low levels in the nucleus and the cytoplasm of a proportion of CPV-infected cells, as well as in cells transfected with the expression plasmid. Virus genomes were prepared with mutations in the splice donor or acceptor sites of the NS2-specific intron or with three different termination codons in the NS2-unique exon. Both splice donor and acceptor mutations resulted in the use of previously cryptic splice sites, and the virus containing the splice donor mutation replicated inefficiently. However, the other four mutant viruses were all viable and replicated efficiently in cat and dog cells, and two mutant viruses that were tested appeared to assemble their capsids in the same manner as did the wildtype. After inoculation of dogs an NS2 mutant virus with a termination codon in the NS2-unique exon replicated to titers similar to those seen for wildtype CPV in several tissues examined.

Closely spaced, fast dynamic movements in disparity vergence

Conflicting theories exist describing how symmetrical vergence responses, the inward or outward turning of the eyes, are mediated. Classical theories describe vergence control as mediated by visual feedback. Extensive experimental evidence indicates that two distinct control components comprise the vergence response, and a recent theory supports the concept that one of these components is not visually guided. Occasionally, saccadic eye movements will respond to a single step stimulus with two closely spaced saccades, a behavior that is indicative of its switching control structure. If a portion of the vergence response is controlled in a manner analogous to saccades, then occasional double fast dynamic components might be expected. During this study, eye movements were recorded in response to symmetrical vergence stimuli of 2, 4, 6, 8, and 10 degrees steps. The left and right eye movements were subtracted to yield a net vergence response, and only convergent responses were investigated. Double fast dynamic components associated with high-velocity movements were observed in all four subjects studied. In double high-velocity component responses, the average peak velocity of both fast dynamic movements was always considerably less than the average peak velocity found when the response to the same stimulus was made with only a single component. Response amplitudes of single and double movements showed that if the primary component of a double response did not reach >/=80% of the stimulus amplitude, a secondary component would be generated to aid the movement. Plots of peak velocity as a function of response amplitude for both double and single movements followed the main sequence for vergence eye movements demonstrating that the first-order dynamic characteristics of all high-velocity components were the same. The time at which maximum velocity occurred (relative to stimulus onset) was also the same for both single component responses and the first component of double responses. The similarity in dynamics and timing implies that the high-velocity components were processed by the same controller mechanism. The existence of double high-velocity movements is indicative of an internal, switching mechanism similar to that found in saccades and is difficult to explain with theories that rely on visual feedback control alone.

Follicular dominance in cattle is associated with divergent patterns of ovarian gene expression for insulin-like growth factor (IGF)-I, IGF-II, and IGF binding protein-2 in dominant and subordinate follicles

A decrease in insulin-like growth factor (IGF) binding protein (BP) amount occurs within the follicular fluid of dominant ovarian follicles. At the same time, concentrations of follicular fluid IGF-I do not change. The mRNA for IGF-I, IGF-II, IGFBP-2, and IGFBP-3, in dominant and subordinate follicles were measured to determine if changes in IGF or IGFBP gene expression are associated with follicular dominance. Heifers were ovariectomized during a follicular wave, either during early-dominance (emerging dominant follicle, 9 mm diameter) or mid-dominance (established dominant follicle, 14-16 mm diameter). Follicles were classified as either dominant (DF), subordinate (SF), or not-recruited (NRF; small antral follicles). mRNA was localized by in situ hybridization and measured by image analyses. The IGF-I mRNA (granulosa cells) was greatest in DF and increased in DF, SF, and NRF from early- to mid-dominance. Likewise, IGF-II mRNA (theca cells) was greatest in DF compared with SF or NRF. The IGFBP-2 mRNA (granulosa cells), however, was nearly undetectable in DF, whereas adjacent SF expressed abundant IGFBP-2 mRNA. The NRF were not uniform in their IGFBP-2 expression because only 5 of 13 NRF had IGFBP-2 mRNA. The IGFBP-3 mRNA (granulosa cells) was found only in two NRF, suggesting that local synthesis is not a predominant source of follicular fluid IGFBP-3. These data show that changes in gene expression for IGFBP-2 are opposite to those for IGF-I or IGF-II. Increased IGF-I and IGF-II mRNA and decreased IGFBP-2 mRNA within the DF may be one mechanism leading to follicular dominance. The opposite pattern of IGFBP-2 gene expression in SF and some NRF may lead to follicular atresia.

Comparative study of the effects of ouabain and digoxin on blood pressure of rats

OBJECTIVE

To compare the effect of ouabain on the blood pressure of rats with that of digoxin to find the evidences of the relationship between endogenous ouabain (EO) and development of hypertension.

METHODS

Sprague-Dawley rats, which were divided into 3 groups, were infused with ouabain (23 x 75 micrograms.kg-1/day, i.p.), digoxin (36 x 84 micrograms.kg-1/day, i.p.) and normal saline (NS) once a day respectively. Systolic blood pressure and body weight were recorded weekly. Five weeks later, rats of ouabain group were randomly assigned to three infusion subgroups: Oc group, continued with ouabain infusion; Od group, added digoxin (73 x 68 micrograms.kg-1/day, i.p.) and Os group, stopped administration of ouabain. Another week later, direct blood pressure was recorded in aorta. Systolic and diastolic cardiac function, plasma renin activity and aldosterone levels of all the rats were measured.

RESULTS

After a latent period of one week, blood pressure of Ouabain group increased significantly [95.4 +/- 11.8 mmHg (1 mmHg = 0.133 kPa) at the beginning of the experiment vs 122.5 +/- 16.9 mmHg at the end of week 6, P < 0.05] with normal plasma renin activity and higher aldosterone (1.28 +/- 0.45 ng/ml vs 0.69 +/- 0.27 ng/ml, P < 0.05). The blood pressure decreased after either withdrawal of ouabain or addition of digoxin (116.3 +/- 14.4 mmHg vs 100 +/- 10.7 mmHg, P < 0.05; 123.9 +/- 13.9 vs 103.3 +/- 10.5 mmHg, P < 0.05, respectively). No difference of blood pressure was found between the digoxin and NS group.

CONCLUSIONS

Our results suggested that EO might be one of the causes of the development of hypertension. Aldosterone might play some role in the mechanism of ouabain-induced hypertension. Digoxin can not induce hypertension. There is a great difference between the effect of ouabain and digoxin on the blood pressure. Moreover, digoxin can reverse the hypertension induced by ouabain.

Cloning and characterization of a novel macrolide efflux gene, mreA, from Streptococcus agalactiae

A strain of Streptococcus agalactiae displayed resistance to 14-, 15-, and 16-membered macrolides. In PCR assays, total genomic DNA from this strain contained neither erm nor mef genes. EcoRI-digested genomic DNA from this strain was cloned into lambda Zap II to construct a library of S. agalactiae genomic DNA. A clone, pAES63, expressing resistance to erythromycin, azithromycin, and spiramycin in Escherichia coli was recovered. Deletion derivatives of pAES63 which defined a functional region on this clone that encoded resistance to 14- and 15-membered, but not 16-membered, macrolides were produced. Studies that determined the levels of incorporation of radiolabelled erythromycin into E. coli were consistent with the presence of a macrolide efflux determinant. This putative efflux determinant was distinct from the recently described Mef pump in Streptococcus pyogenes and Streptococcus pneumoniae and from the multicomponent MsrA pump in Staphylococcus aureus and coagulase-negative staphylococci. Its gene has been designated mreA (for macrolide resistance efflux).

mefE is necessary for the erythromycin-resistant M phenotype in Streptococcus pneumoniae

Recently, it was shown that a significant number of erythromycin-resistant Streptococcus pneumoniae and Streptococcus pyogenes strains contain a determinant that mediates resistance via a putative efflux pump. The gene encoding the erythromycin-resistant determinant was cloned and sequenced from three strains of S. pneumoniae bearing the M phenotype (macrolide resistant but clindamycin and streptogramin B susceptible). The DNA sequences of mefE were nearly identical, with only 2-nucleotide differences between genes from any two strains. When the mefE sequences were compared to the mefA sequence from S. pyogenes, the two genes were found to be closely related (90% identity). Strains of S. pneumoniae were constructed to confirm that mefE is necessary to confer erythromycin resistance and to explore the substrate specificity of the pump; no substrates other than 14- and 15-membered macrolides were identified.

Protein kinase C activity and its effect on progesterone production by large and small porcine luteal cells

Protein kinase C (PKC) activity and its effect on progesterone production were investigated using porcine large and small luteal cells (LLC and SLC). Corpora lutea (CL) were surgically collected from pigs on Day 10 of the estrous cycle (Day 0 = onset of standing estrus). Luteal cells were dissociated by collagenase; LLC and SLC were further separated on a discontinuous Ficoll gradient. In a dose-response experiment with phorbol 12-myristate 13-acetate (PMA, a stimulator of PKC), progesterone production was not affected by 0.01 and 0.1 microM PMA, but was stimulated by 1 microM PMA. In a time series experiment, progesterone secretion was increased by 1 and 10 microM PMA in LLC by 60-150 min, and by 1 microM PMA in SLC during 120 and 150 min of incubation. However, 4 alpha-phorbol ester did not affect progesterone synthesis. H-7, a PKC inhibitor, blocked PMA-stimulated progesterone secretion by LLC during 3 hr of incubation. Of the PKC activators tested at 10 microM, PMA significantly stimulated cytosolic PKC activity over that of natural PKC activators in both LLC and SLC, whereas 4 alpha-phorbol ester did not affect PKC activity. H-7 inhibited PMA-stimulated PKC activity. PS (1-phosphatidyl-L-serine) + CA+2 and PS+DG (1,2-dioleoyl-sn-glycerol) + Ca+2 stimulated PKC activity. The results demonstrate that activation of PKC can increase progesterone secretion by porcine luteal cells from Day 10 of the estrous cycle and suggest PKC can have multiple effects in regulating luteal function.

Programmed cell death in human ovary is a function of follicle and corpus luteum status

Although extensive investigation on follicular apoptosis (programmed cell death) has been conducted in the infraprimate ovary, there is little information regarding apoptosis and its relationship to follicular status in the human. In this study, apoptosis was investigated in 116 human ovarian follicles (primordial to dominant) and 5 corpora lutea from a total of 27 premenopausal women. Follicles and corpora lutea were evaluated for the presence of DNA fragmentation, characteristic of apoptosis, by two methods: in situ hybridization using 3' end-labeling of DNA with digoxigenin-labeled nucleotides and subsequent digoxigenin antibody and peroxidase staining, and/or biochemical analysis of low molecular weight DNA laddering. Follicle functional status was evaluated by determining follicle sizes and follicular fluid androgen/estrogen (A/E) ratios. No apoptosis was observed in 67 primordial, primary, or secondary follicles. Positive staining for DNA fragmentation was found in a few granulosa cells in 0.1- to 2-mm follicles, whereas abundant staining in granulosa was detected in 2.1- to 9.9-mm follicles. In contrast, no DNA fragmentation was detected in dominant follicles (10-16 mm). The frequency of apoptosis in follicles was calculated to be 37% in 0.1- to 2-mm follicles, 50% in 2.1- to 5-mm follicles, and 27% in 5.1- to 9.9-mm follicles. Abundant low molecular weight DNA laddering was only found in androgen-dominant follicles and not in estrogen-dominant follicles. Positive staining for DNA fragmentation and low molecular weight DNA laddering were observed in degenerating but not healthy-appearing corpora lutea. In the former, DNA fragmentation was found primarily in large luteal cells. These data suggest that follicular atresia in human ovary results from normal programmed cell death and primarily occurs in the granulosa cell layers of the early antral and < 10-mm antral follicles primarily. Furthermore, because apoptosis occurs as early as the 200-mm stage, follicle selection may begin as early as the initial formation of the antrum. The results also suggest that degeneration of the corpus luteum occurs by apoptotic mechanisms.

Glucose-induced microautophagy in Pichia pastoris requires the alpha-subunit of phosphofructokinase

We have characterized biochemically, morphologically, and genetically two distinct pathways for the selective degradation of peroxisomes in Pichia pastoris. These pathways are independently regulated and analogous to microautophagy and macroautophagy that have been defined in mammalian cells. When P. pastoris is grown in methanol, cytosolic and peroxisomal enzymes necessary for methanol assimilation are synthesized. During adaptation from methanol to glucose, these enzymes are rapidly and selectively degraded within the yeast vacuole by microautophagy. We have isolated gsa mutants that are defective in glucose-induced selective autophagy of peroxisomes. In this study, we have shown that gsa1 is unable to sequester peroxisomes into the yeast vacuole. In addition, we provide evidence that the glucose-induced selective autophagy 1 (GSA1) protein is the alpha subunit of the phosphofructokinase enzyme complex encoded by PFK1. First, we can rescue the gsa1 mutant by transformation with a vector containing PFK1. Second, cellular levels of both PFK1 mRNA and phosphofructokinase activity are dramatically reduced in gsa1 when compared to the parental GS115. Third, a PFK1 knockout (delta pfk1) is unable to degrade alcohol oxidase during glucose adaptation. As observed in gsa1, the peroxisomes in delta pfk1 remain outside the vacuole during adaptation. Our data are consistent with the concept that PFK1 protein is required for an event upstream of vacuole degradation (i.e. signaling, selection, or sequestration). However, the degradation of peroxisomes does not require a catalytically active phosphofructokinase. The inability of delta pfk1 cells to degrade alcohol oxidase can be rescued by transformation with either normal PFK1 or mutant pfk1 whose catalytic site had been inactivated by a single amino acid mutation. We propose that PFK1 protein directly modulates glucose-induced microautophagy independent of its ability to metabolize glucose intermediates.

[Expression of IL-4 and IL-10 by PBMC and tumor tissues in cancer patients]

Using biological activity assay, the production of IL-4 and IL-10 by peripheral blood mononuclear cells (PBMC) was studied in patients with nasopharyngeal carcinoma and lymphoma. The IL-2, IL-4 and IFN gamma levels in both cancer patients were lower than that in normal subjects. In contrast, the IL-10 level was higher in both cancer patients. When rIL-2 was added into the cytokine production system, IL-2, IL-4, and IFN gamma level were upregulated in lymphoma patients. However, in the patients of nasopharyneal carcinoma, only IL-2 level was upregulated. IL-10 activity could not be affected by exogenous IL-2 in both cancer patients. The results of negative IL-4 activity and higher positive percentage (84.6%) of IL-10 activity in ascites from patients with ovarian carcinoma were corresponded to the patients with nasopharyngeal carcinoma and lymphoma. By using in situ hybridization technique, the expression of IL-4 and IL-10 was studied in tumor tissues from patients with gastric, esophageal and breast carcinomas. There was no differences of the percentage of IL-4 and IL-10 expression among three kinds of tumor tissues, the range of positive percentage was 40%-70%. These results indicate that the correction of abnormal upregulation of IL-10 activity should be considered for cancer immunotherapy.

Cardiac myocyte volume, Ca2+ fluxes, and sarcoplasmic reticulum loading in pressure-overload hypertrophy

Alterations in cellular Ca2+ transport and excitation-contraction coupling may contribute to dysfunction in cardiac hypertrophy. Left ventricular myocytes were isolated from rat hearts after 15-18 wk of suprarenal abdominal aortic banding to evaluate the hypothesis that hypertrophy alters the relationship between Ca2+ current (ICa) and sarcoplasmic reticulum (SR) Ca2+ load during steady-state voltage-clamp depolarization. Mean arterial pressure (MAP) and heart weight-to-body weight ratio of banded (B) animals were significantly higher than in control or sham-operated animals (C). Isolated myocyte dimensions and volume increased in parallel with whole heart hypertrophy and elevation in MAP. However, the relationship between membrane surface area (measured by capacitance) and cell volume (measured by laser scanning confocal microscopy) was unaltered (C: 8.9 +/- 0.3; B: 8.5 +/- 0.4 pF/pl). No differences in the voltage dependence of ICa activation, steady-state inactivation, or recovery from inactivation were detected between C and B myocytes. Maximal ICa density for the two groups was also not different either under basal conditions (C: 4.28 +/- 0.98; B: 4.57 +/- 0.60 pA/pF) or in the presence of 1 microM isoproterenol (C: 16.6 +/- 2.3; B: 16.5 +/- 2.3 pA/pF). The fraction of Ca2+ released from the SR by a single twitch was 55.4 +/- 9.4% in C and 37.1 +/- 6.9% in B (not significantly different). Steady-state Ca2+ influx during a twitch was calculated in units of micromoles per liter of nonmitochondrial volume from the integral of ICa (C: 13.4 +/- 0.7 microM; B: 13.3 +/- 0.8 microM). The SR Ca2+ load was similarly calculated by integration of Na+/Ca2+ exchange current induced by rapid caffeine application (C: 140 +/- 9 microM; B: 169 +/- 18 microM). We conclude that significant cellular hypertrophy is associated with proportional increases in sarcolemmal ICa influx, SR Ca2+ loading, and the amount of SR Ca2+ released in this model of pressure overload.

Ethylbenzene modulates the expression of different cytochrome P-450 isozymes by discrete multistep processes

Ethylbenzene (EB) treatment to male Holtzman rats was shown to alter the expression of cytochrome P-450s 1A1, 2B, 2C11, 2E1, and 3A, with several isozymes exhibiting complex multiphasic induction patterns when treated for 1 and 3 days with the alkylbenzene. Male rats were treated with daily i.p. injections of EB for either one or three days, and the effects on P-450 dependent activities, P-450 immunoreactive protein levels and their corresponding mRNA levels were measured. Although levels of P-450 2B, 2C11, 2E1, and 3A were all modulated by EB treatment, each exhibited different temporal characteristics. P-450 2B1/2B2 were induced after a single EB exposure and continued to be elevated after EB treatment for 3 days. However, P-450 2B1 and 2B2 mRNA levels were elevated about 50-fold after a single injection, and returned to control values after continued EB administration. P-450 2C11 expression was decreased to about 45% of controls after either single or repeated EB exposure with corresponding changes being observed in the levels of 2C11 mRNA. P-450 2E1 was induced by EB according to a complex multistep induction pattern. Both P-450 2E1 protein and RNA levels were increased 2-4-fold after a single EB treatment but returned to control values after continued administration. P-450 3A-dependent testosterone 2beta-hydroxylation and P-450 3A immunoreactive protein levels were both increased about 3-fold after a single EB treatment, whereas levels were only elevated 2-fold after EB treatment for 3 days. In contrast, P-450 3A2 mRNA was unaffected by a single EB injection but was increased 3.5-fold with repeated administration. Changes in P-450 3A1/2 were similar to those observed with P-450 3A2, whereas changes in P-450 3A1/23 and 3A23 mRNAs were not detectable. These data indicate that while EB can influence the expression of several P-450 isozymes, the hydrocarbon appears to alter P-450 expression by acting at different regulatory steps.

Progesterone production in vitro by mouse luteal cells: response to follicle-stimulating hormone, luteinizing hormone, and prolactin

The purpose of this study was to determine the effects of ovine follicle-stimulating hormone (FSH), luteinizing hormone (LH); prolactin, and recombinant FSH and a protein kinase C activator (phorbol 12-myristate 13-acetate [PMA]) on progesterone production by dispersed luteal cells (large + small) from Day 4 pregnant mice. Corpora lutea (CL) were collected on Day 4 of pregnancy (Day 1 = sperm positive smear), and dispersed luteal cells were isolated using collagenase. After overnight incubation, the luteal cells were incubated with or without FSH, LH, prolactin, or recombinant human FSH or PMA for 4 hr or an additional 24 hr at 37 degrees C; media were collected and progesterone was determined by RIA. Ten nanograms and 100 ng of ovine FSH, LH and prolactin were all equally effective in stimulating progesterone synthesis in media recovered after 24 hr of incubation. Moreover, the combination of all three gonadotropins yielded maximum levels of progesterone indicating a luteotrophic complex in vitro, paralleling previous in vivo findings. Recombinant human FSH-devoid of LH contamination-at doses of 10 and 100 ng also significantly stimulated progesterone synthesis, which strongly suggests that FSH has luteotropic activity in the mouse, thus agreeing with our previous in vitro results with CL of the pregnant hamster and rat. One hundred nanomolar PMA by itself did not affect progesterone production but significantly decreased dibutyrl cAMP-, forskolin-, FSH-, and LH-induced progesterone production, suggesting that activation of protein kinase C may block the luteotropic effects of LH and FSH during murine pregnancy.

Time course for the modulation of hepatic cytochrome P450 after administration of ethylbenzene and its correlation with toluene metabolism

The goal of the present study was to examine the time course for changes in P450 expression and hydrocarbon metabolism after acute treatment with the simple aromatic hydrocarbon ethylbenzene (EB) and to correlate these alterations with the changes observed in alkylbenzene metabolism. Male Holtzman rats were treated with a single intraperitoneal injection of EB, and the effects on specific P450-dependent activities, immunoreactive P450 isozyme levels, and RNA levels were measured at various times after injection. Toluene was used as the test alkylbenzene for examination of the EB-mediated changes on in vitro hydrocarbon metabolism. In untreated rats, toluene was metabolized almost entirely by aliphatic hydroxylation (to benzyl alcohol); however, in EB-treated rats, significant quantities of benzyl alcohol, o-cresol, and p-cresol were produced. Interestingly, 5-10 h after EB treatment, there was a 40% decrease in benzyl alcohol production. By 24 h, rates of benzyl alcohol formation returned to control levels, whereas there was a 7-fold increase in o-cresol and a greater that 50-fold increase in p-cresol production. The changes in the disposition of toluene were then correlated with changes in particular P450 isozymes. Several P450 isozymes were induced after EB administration. P450 2B1/2-dependent testosterone 16 beta-hydroxylation and P450 2B1/2-immunoreactive protein were elevated 30-fold after EB administration, reaching maxima by 24 h and remaining elevated 48 h after exposure. Changes in P450 2B1 and 2B2 RNA preceded those of the proteins. Similar results were observed with P450 1A1. P450 2E1 RNA levels were elevated after a single EB injection. However, the elevation in P450 2E1-dependent activities and immunoreactive protein levels preceded the changes in RNA, suggesting that multiple steps are affected by EB exposure. In contrast to the increases in some isozymes, P450 2C11 protein was rapidly suppressed (within the first 2-10 h) after hydrocarbon exposure, suggestive of a destabilization of the protein. When comparing the changes in P450 isozymes to alterations in toluene metabolism, the immediate suppression in aliphatic hydroxylation of toluene (in the first 5-10 h) was consistent with the decrease in P450 2C11. Subsequent to this effect, P450 2B1/2 and 2E1 were induced, which elevated production of this metabolite to control levels. The increase in the aromatic hydroxylation of toluene to both o, and p-cresol was consistent with the induction of P450s 2B1/2, 2E1, and 1A1.

[Antagonistic effect of calcitonin gene related peptide on arrhythmia in rats]

Premature ventricular contraction (PVC), ventricular tachycardia (VT) and ventricular fibrillation (VF) were developed by endothelin-1 (ET-1) injected into the coronary ostia at the dose of 900 pmol/kg in anesthetized rats. No arrhythmia was elicited but blood pressure fell temporarily by calcitonin gene related peptide (CGRP), the injection into the coronary ostia. After pretreatment with CGRP incidence and severity of arrhythmia decreased at the same ET-1 dose. Arrhythmia score in CGRP 1200 pmol/kg + ET-1 group was lower than that in ET-1 group (P < 0.01). The results revealed that antiarrhythmic effect of CGRP may be partially brought about by its antagonistic effect against ET-1 induced arrhythmia.

Characterization of Organofunctional Silane Films on Zinc Substrates

Organofunctional silane films formed on pure zinc substrates from aqueous solutions were characterized by ellipsometry, contact angle measurements, reflection absorption infrared spectroscopy (RAIR), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). The silanes studied were gamma-aminopropyltriethoxysilane (gamma-APS) and gamma-ureidopropyltrialkoxysilane (gamma-UPS). The deposition parameters included solution concentration, solution dipping time, and pH value of the applied solution. Effects of these deposition variables on the thickness of the film, the surface energy of the film, the chemical structure of the film, and the surface topography of the film are discussed. The effect of film aging time on the surface energy of silane-coated pure zinc substrates was also studied. It was found that the silane film thickness obtained depends primarily on the applied solution concentration and is independent of the solution dipping time. The molecular orientations of the applied silane film are determined by the pH value of the applied silane solution and the isoelectric point of the metal substrates. The deposition window in terms of pH value for zinc substrates was between 6 and 9. The total surface energy of silane-coated pure zinc substrate decreases steeply with film aging time for gamma-APS but not for gamma-UPS. The stability of both silane films improved after aging in the air.

Molecular cloning and functional analysis of a novel macrolide-resistance determinant, mefA, from Streptococcus pyogenes

Several streptococcal strains had an uncharacterized mechanism of macrolide resistance that differed from those that had been reported previously in the literature. This novel mechanism conveyed resistance to 14- and 15-membered macrolides, but not to 16-membered macrolides, lincosamides or analogues of streptogramin B. The gene encoding this phenotype was cloned by standard methods from total genomic digests of Streptococcus pyogenes 02C1064 as a 4.7 kb heterologous insert into the low-copy vector, pACYC177, and expressed in several Escherichia coli K-12 strains. The location of the macrolide-resistance determinant was established by functional analysis of deletion derivatives and sequencing. A search for homologues in the genetic databases confirmed that the gene is a novel one with homology to membrane-associated pump proteins. The macrolide-resistance coding sequence was subcloned into a pET23a vector and expressed from the inducible T7 promoter on the plasmid in E. coli BL21(DE3). Physiological studies of the cloned determinant, which has been named mefA for macrolide efflux, provide evidence for its mechanism of action in host bacteria. E.coli strains containing the cloned determinant maintain lower levels of intracellular erythromycin when this compound is added to the external medium than isogenic clones without mefA. Furthermore, intracellular accumulation of [14C]-erythromycin in the original S. pyogenes strain was always lower than that observed in erythromycin-sensitive strains. This is consistent with a hypothesis that the gene encodes a novel antiporter function which pumps erythromycin out of the cell. The gene appears to be widely distributed in S. pyogenes strains, as demonstrated by primer-specific synthesis using the polymerase chain reaction.

[Expression of retroviral transmembrane envelope protein p15E in human malignant cells]

Malignant tumor growth is always accompanied with immune suppression. Tumor-derived immuno-suppressive factors, among others, are thought to be responsible, but their nature is not well defined. The paper reports on the expression of an immuno-suppressive retroviral transmembrane envelope protein p15E at different levels in human cancer cells. By using immunohistochemistry, enzyme-linked immunosorbent assay, flow cytometry and in situ hybridization, p15E expression could be demonstrated in cancers of the esophagus, nosopharynx, rectum, ovary (including malignant effusion and cell lines), stomach and breast. Enhanced expression of p15E was also observed in activated lymphocytes of cancer patients as shown by RT-PCR technique. The results indicate that p15E of tumor origin, and perhaps that from activated lymphocytes, may contribute to the immune suppression associated with malignancy.

A study of time window for oxidative stress associated with myocardial ischemia and reperfusion

OBJECTIVE

To investigate the time window for oxidative stress occurred in myocardial tissue and associated with reperfusion.

METHODS

Thirty nine conscious rabbits were subjected to 0.5 hours (h) of myocardial ischemia and reperfusion for 0 h, 6 h, 24 h and 72 h, respectively, and nine rabbits served as controls. Activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-px) and myeloperoxidase (MPO), and contents of GSH and malondyaldehyde (MDA) were measured in myocardial tissues taken from ischemic non-necrotic area (INNA), ischemic necrotic area (INA) and non-ischemic area (NIA), respectively.

RESULTS

The antioxidant status of INNA was weakened at 6th h, 24th h, and 48th h of reperfusion. Activities of Mn-SOD and Cu-Zu-SOD returned to normal value at 72nd h of reperfusion, but GSH-px activity and GSH content remained in lower value. MDA content had a marked increase at 6th h, 24th h, 48th/h and 72nd h of reperfusion. MPO activity had a progressive increase after reperfusion, with its peak value at 48th h, and PMN accumulation occurred mostly in necrotic zone and its outer board zone. A mild oxidative stress also occurred in non-ischemic tissue, but without obvious neutrophils infiltration.

CONCLUSIONS

The time window for oxidative stress associated with myocardial ischemia and reperfusion lasts for at least 72 h, and PMN infiltration is one of the most important factors of delayed myocardial reperfusion injury.

Messenger ribonucleic acid for insulin-like growth factors-I and -II, insulin-like growth factor-binding protein-2, gonadotropin receptors, and steroidogenic enzymes in porcine follicles

Several aspects of growth, development, and steroidogenesis in ovarian follicles are controlled by the interaction of insulin-like growth factors (IGF-I and IGF-II) and gonadotropins (LH and FSH). The objective of this study was to determine the developmental stage and location at which mRNA for IGF, IGF-binding protein (IGFBP)-2, gonadotropin receptors, and steroidogenic enzyme genes are expressed within porcine follicles. Ovaries from pigs on Days 10 (n = 3; midluteal phase) and 19 (n = 3; preovulatory phase) of the estrous cycle were collected, frozen, and sectioned. The mRNA for IGF-I, IGF-II, IGFBP-2, LH receptor, FSH receptor, cytochrome P450 side-chain cleavage (P450scc), 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD), 17 alpha-hydroxylase (P45017 alpha), and aromatase (P450arom) were detected by in situ hybridization, and relative amounts were determined by image analysis. Expression of mRNA for IGF-I and IGF-II was cell specific (granulosa and theca interna cells, respectively) and increased with follicular size. The IGFBP-2 mRNA was expressed in greater amounts for theca interna cells than for granulosa cells. The pattern of expression for LH and FSH receptors diverged as follicles grew. For LH receptor, mRNA was detected in the theca interna cells of small antral follicles and in both the theca interna and granulosa cells of large antral follicles. Amount of LH receptor mRNA increased with follicular diameter. For FSH receptor, mRNA increased as follicles grew to a small antral size. However, FSH receptor mRNA disappeared in large antral follicles on Day 19 of the estrous cycle. Steroidogenic enzyme mRNA for 3 beta-HSD (theca interna cells), P450scc (theca interna cells), P45017 alpha (theca interna cells), and P450arom (granulosa cells) increased with follicular diameter. In summary, coordinated expression of IGF, IGFBP-2, gonadotropin receptors, and steroidogenic enzyme mRNA throughout different stages of follicular development was observed. Changes in mRNA suggested increased IGF-I and -II action and a switch from FSH to LH dependence in porcine preovulatory follicles.

Messenger ribonucleic acid expression for growth hormone receptor, luteinizing hormone receptor, and steroidogenic enzymes during the estrous cycle and pregnancy in porcine and bovine corpora lutea

Growth hormone (GH) and luteinizing hormone (LH) are pituitary hormones involved in steroidogenesis in the corpus luteum (CL). The objectives of Experiment I were to determine mRNA expression for GH receptor (GHR) and LH receptor (LHR) in porcine luteal tissues during the estrous cycle and pregnancy and to relate changes in these receptor mRNA with changes in steroidogenic enzyme mRNA for cytochrome P450 side-chain cleavage enzyme (P450sec) and 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD). Ovaries were collected from gilts during the estrous cycle (day 10 [n = 3] and Day 19 [n = 3, regressed CL) and pregnancy (Day 25 [n = 3] and Day 44 [n = 3]). Tissues were frozen in liquid nitrogen and sectioned. Messenger RNA was detected by in situ hybridization, and relative mRNA amounts were determined by image analysis. The mRNA for GHR, LHR, P450sec, and 3 beta-HSD were detected in the CL on Day 10 of the estrous cycle. None of these mRNA were specific to cither large luteal cells (LLC) or small luteal cells (SLC). On Day 19 of the estrous cycle (regressed CL), mRNA for GHR, P450sec, and 3 beta-HSD were decreased (P < 0.01) whereas LHR mRNA disappeared (P < 0.01). During pregnancy, mRNA expression increased 2.1-, 1.4-, 1.4-, and 1.2-fold for GHR, LHR, P450sec, and 3 beta-HSD, respectively (P < 0.05). The luteal location of GHR mRNA in the pig did not agree with that found in our previous studies of GHR mRNA or protein in cattle. Therefore, the objective of Experiment 2 was to measure GHR mRNA by the use of in situ hybridization in bovine CL during the estrous cycle (Day 14; n = 2) and pregnancy (Day 25; n = 2). In situ hybridization demonstrated specific expression of GHR mRNA in the LLC of cattle. Furthermore, GHR mRNA increased 1.8-fold in CL on Day 25 of pregnancy compared with GHR mRNA on Day 14 of the estrous cycle (P < 0.01). In adjacent sections, the LHR mRNA was most highly expressed in clusters of SLC with 1.6-fold more mRNA on Day 25 of pregnancy compared with Day 14 of the estrous cycle (P < 0.01). These results suggest that: 1) mRNA for LHR, GHR, P450sec, and 3 beta-HSD are differentially regulated during the estrous cycle and pregnancy and 2) the cellular location of GHR differs for pigs and cattle, with highly specific expression of GHR in bovine LLC but not porcine LLC. This may suggest different functions for GH in the CL of these species.

[A pathologic study of delayed myocardial reperfusion injury]

This study was designed to investigate whether a new irreversible injury to the myocardium can occur 6 hours after reperfusion following ischemia. Conscious rabbits were subjected to myocardial ischemia for 30 minutes, followed by reperfusion. Horseradish peroxidase (HPR) tracing with TTC staining and histological quantification were used to study the histopathological changes in myocardial tissues. Necrotic myocardium at 6 hours after reperfusion gave positive HRP results and viable myocardium at 24 hours after reperfusion gave positive TTC results. Some myocardial tissue between the above two regions were found to be HRP negative as well as TTC negative, indicating that myocardial tissue death occurred between 6 to 24 hours after reperfusion. The myocardial infarct size at 24, 48, and 72 hours after reperfusion were 7.0%, 5.1% and 3.2% larger than that 6, 24 and 48 hours respectively. Therefore, new irreversible myocardial injury in the rabbit can still occur after 6 hours of reperfusion following myocardial ischemia for 30 minutes and cumulative myocardial injury from 6 to 72 hours after reperfusion can result in a marked extension of the size of myocardial infarct.

Comparison of sarcolemmal calcium channel current in rabbit and rat ventricular myocytes

1. Fundamental properties of Ca2+ channel currents in rat and rabbit ventricular myocytes were measured using whole cell voltage clamp. 2. In rat, as compared with rabbit myocytes, Ca2+ channel current (ICa) was half-activated at about 10 mV more negative potential, decayed slower, was half-inactivated (in steady state) at about 5 mV more positive potential, and recovered faster from inactivation. 3. These features result in a larger steady-state window current in rat, and also suggest that under comparable voltage clamp conditions, including action potential (AP) clamp, more Ca2+ influx would be expected in rat myocytes. 4. Ca2+ channel current carried by Na+ and Cs+ in the absence of divalent ions (Ins) also activated at more negative potential and decayed more slowly in rat. 5. The reversal potential for Ins was 6 mV more positive in rabbit, consistent with a larger permeability ratio (PNa/PCs) in rabbit than in rat. ICa also reversed at slightly more positive potentials in rabbit (such that PCa/PCs might also be higher). 6. Ca2+ influx was calculated by integration of ICa evoked by voltage clamp pulses (either square pulses or pulses based on recorded rabbit or rat APs). For a given clamp waveform, the Ca2+ influx was up to 25% greater in rat, as predicted from the fundamental properties of ICa and Ins. 7. However, the longer duration of the AP in rabbit myocytes compensated for the difference in influx, such that the integrated Ca2+ influx via ICa in response to the species-appropriate waveform was about twice as large as that seen in rat.

Alendronate stimulation of nocturnal parathyroid hormone secretion: a mechanism to explain the continued improvement in bone mineral density accompanying alendronate therapy

The major effect of currently available antiresorptive therapy for osteoporosis is to slow or arrest bone loss. Although antiresorptive therapies demonstrate increases in bone mineral density, the effect is usually transient, and a plateau in bone mineral density usually emerges at 1 year. A unique and unexplained feature of treatment with the antiresorptive agent alendronate is continued, and steady improvement in bone mineral density occurs in years 2 and 3. We postulated that a potential mechanism for this unanticipated effect might be an exaggerated nocturnal increase in parathyroid hormone (PTH), which can act as an anabolic agent. We examined day-night levels and diurnal variation of PTH, serum calcium, ionized calcium, and markers of bone formation (osteocalcin) and resorption (N-telopeptide cross-links) over 24 hours in a randomly selected subset of 38 women (placebo: N = 13; mean age +/- SD, 69 +/- 3 years; alendronate: N = 25; mean age +/- SD, 69 +/- 3 years) who had completed 12 to 15 months of a larger (N = 120), randomized, double-blind, placebo-controlled trial with alendronate, 5 mg/day. By month 12, increases in the bone density of the spine (4.6%) and femoral neck (2.7%) were observed in the group treated with alendronate compared with placebo, (spine, 2.2%, p = .05; femoral neck, -0.2%, p < or = .05). Mean nocturnal PTH (10 PM-8 AM) was 21% higher (39 versus 32 pg/ml), and nocturnal serum calcium averaged 3% lower (8.7 versus 9.0 mg/dL) in the alendronate-versus-placebo group (both p < or = .05). Daytime levels (8 AM-10 PM) of PTH did not differ significantly between groups. We observed accompanying decreases in coupled markers of bone formation (osteocalcin, 38% lower, p < or = .01) and resorption (N-telopeptide cross-links, 50% lower, p < or = .01) in the alendronate group. Significant diurnal variations of PTH, serum calcium, and osteocalcin were present in both groups. We conclude that following 1 year of alendronate therapy, women have significant increases in bone mineral density and in nocturnal PTH levels, associated with decreases in nocturnal serum calcium and markers of bone turnover with maintenance of the diurnal variation. The nocturnal increase in PTH may mimic the anabolic effect of low-dose intermittent PTH administration to stimulate bone formation. Therefore, the increase might be a potential mechanism to explain the continued improvement in bone density following more than 1 year of alendronate therapy.

Human p300 protein is a coactivator for the transcription factor MyoD

Human p300 protein is a cellular target of adenoviral E1A oncoprotein and a potential transcriptional coactivator. Both p300 and Rb family protein-binding regions of E1A are required for the repression of muscle gene expression, which is regulated by MyoD family transactivators. This implies that p300 is involved in MyoD-dependent transactivation. We show that the repression of MyoD-mediated E box (MyoD consensus) reporter activity by E1A is correlated with its interaction with p300, indicating that p300 participates in MyoD-dependent transactivation. In addition, p300 is able to interact both in vivo and in vitro with MyoD through a portion at the carboxyl-terminal cysteine/histidine-rich domain and associates with the components of the basal transcriptional complex through its two separate transactivation domains at the amino and carboxyl termini. Consistent with its role as a coactivator, p300 potentiates MyoD-activated transcription.

Effects of growth hormone, prolactin, insulin-like growth factors, and gonadotropins on progesterone secretion by porcine luteal cells

Growth hormone (GH) and IGF-I have receptors within the corpus luteum (CL) and stimulate CL function. Our objective was to investigate the effects of GH, prolactin (PRL), IGF-I, IGF-II, LH, and FSH on progesterone secretion by porcine luteal cells during mid-pregnancy. Gilts (crossbred Yorkshire/Landrace) were slaughtered on d 44 of pregnancy and CL were collected. Large and small luteal cells (LLC and SLC, respectively) were obtained from dissociated CL and separated by elutriation. Luteal cells were incubated with 0, 1, 10, or 100 ng/mL of GH, PRL, IGF-I, IGF-II, LH, and FSH or combinations of 10 ng/mL of these reagents for 24 or 48 h. Culture media were harvested and concentrations of progesterone analyzed by radioimmunoassay. Growth hormone, PRL, and IGF-I increased (P < .05; 100 ng/mL dose) concentrations of progesterone in media of LLC. Insulin-like growth factor-II, LH, and FSH had no effect on progesterone in LLC cultures. In SLC cultures, GH, PRL, IGF-I, IGF-II, and FSH failed to stimulate progesterone secretion, whereas LH increased progesterone secretion (linear effect of dose; P < .05). Combinations (10 ng/mL each hormone) of GH and IGF-I or PRL and IGF-I increased progesterone secretion by LLC compared with control, GH, PRL, or IGF-I alone (P < .05). Similar combinations of GH or PRL with IGF-I had no effect on SLC. Conclusions are that GH and PRL are stimulatory to progesterone secretion by LLC (location of GH receptor) and SLC are responsive to LH during mid-pregnancy. Both GH and PRL are synergistic with IGF-I for increased progesterone secretion.

Responses of porcine corpora lutea to somatotropin administration during pregnancy

The effects of somatotropin (ST) on functions of porcine corpora lutea (CL) during pregnancy were investigated. Twenty-four crossbred (Yorkshire/Landrace) gilts from d 30 to 43 of pregnancy were injected daily with 5 mg of recombinant porcine somatotropin (rpST; n = 12) or 1 mL of saline (control, n = 12). Blood was collected on d 30, 37, and 43 for analyses of plasma progesterone. Gilts were killed on d 44 of pregnancy, and mRNA were isolated from CL, ovary, and liver. Messenger RNA expression for LH receptor, FSH receptor, ST receptor, 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD), and cytochrome P450 side-chain cleavage enzyme (SCC) were measured. Liver, CL, and ovary contained a 4.7-kb mRNA of ST receptor, but the liver contained more mRNA for ST receptor than did CL or ovary (.97 +/- .18, .47 +/- .04, and .25 +/- .04 units, respectively). There were two variants of LH receptor mRNA in CL (6.8 and 4.4 kb). The CL also contained a 1.8-kb mRNA of SCC and a 1.7-kb mRNA of 3 beta-HSD. No FSH receptor mRNA was detected in CL of the pig. The rpST treatment did not affect the mRNA level of ST receptor, 3 beta-HSD, SCC, or 4.4-kb mRNA of the LH receptor. The 6.8-kb mRNA for the LH receptor was decreased (P < .05) by rpST (.56 +/- .04 vs .78 +/- .05 units). Furthermore, concentrations of plasma progesterone decreased (P < .001) in gilts treated with rpST. Decreased luteal function was associated with decreased expression of LH receptor in rpST-treated gilts. The luteotropic effects of ST observed in vitro do not necessarily occur in vivo when gilts are administered rpST during pregnancy.

Oral alendronate induces progressive increases in bone mass of the spine, hip, and total body over 3 years in postmenopausal women with osteoporosis

To determine the effects of long-term daily oral alendronate sodium (ALN) on bone mass in postmenopausal women with osteoporosis, 19 centers enrolled 516 postmenopausal women aged 45-80 years with spine bone mineral density (BMD) at least 2.5 SD below the mean for young premenopausal women in a 3-year, double-blind, placebo-controlled study. Subjects were randomly allocated to one of four treatment groups: placebo; alendronate, 5 or 10 mg/day for 3 years; or alendronate, 20 mg/day for 2 years followed by 5 mg/day for the 3rd year. All patients received 500 mg/day of supplemental calcium to ensure adequate calcium intake. BMD was measured by dual-energy X-ray absorptiometry at several skeletal sites. Nonsignificant mean decreases in BMD of the spine, femoral neck, and trochanter of 0.6, 0.7, and 0.4%, respectively, occurred in the placebo group at 3 years. Relative to placebo-treated patients, spine BMD increased by 5.4%, 7.4%, and 8.4% in the 5, 10, and 20/5 mg ALN groups, respectively. Increases at the femoral neck were 3.5%, 5.5%, and 4.3%, and those at the trochanter were 5.1%, 7.2%, and 7.2%, respectively. Thus, efficacy of 10 and 20/5 mg ALN was similar, whereas the 5 mg dose was less effective. BMD continued to increase over the entire 3-year study duration in the ALN-treated groups and, compared with the other dosage groups, 10 mg ALN produced the largest gains in BMD during the 3rd year. Changes in biochemical markers of bone turnover and mineral homeostasis confirmed the effect of ALN to decrease bone turnover to a new steady-state level. The safety and tolerability of ALN were comparable with those of placebo. In summary, 10 mg daily oral ALN given for 3 years significantly and progressively increases bone mass and is a generally well-tolerated treatment for osteoporosis in postmenopausal women.