A 2-year report on maxillary and mandibular fixed partial dentures supported by Astra Tech dental implants. A comparison of 2 implants with different surface textures

In 50 partially edentulous patients, 133 (48 maxillary; 85 mandibular) Astra Tech dental implants of 2 different surface textures (machined; TiO-blasted) were alternately installed, supporting 52 fixed partial dentures (FPDs). Before abutment connection 2 machined implants (1 mandibular; 1 maxillary) were found to be non-osseointegrated and were replaced. Another implant could not be restored due to a technical complication. Two FPDs were remade because of technical complications, both because of abutment fractures. Thus, after 2 years in function, the cumulative survival rates were 97.7% and 95.7% for implants and prostheses, respectively. There was no statistically significant difference in survival rate between the 2 types of implants, 100% (TiO-blasted) vs 95.3% (machined), P = 0.24. After 2 years in function, when both jaw and type of implants were combined, the mean (SD) marginal bone loss was 0.24 (0.69) mm. No statistically significant difference in bone loss was found between the 2 types of implant after 2 years of loading, 0.04 (0.82) mm, P > 0.30.

Primary structure, distribution, and effects on motility of CGRP in the intestine of the cod Gadus morhua

Calcitonin gene-related peptide (CGRP) was isolated from an extract of the intestine of the cod Gadus morhua. The primary structure of this 37-amino acid peptide was established as follows: ACNTA TCVTH RLADF LSRSG GIGNS NFVPT NVGSK AF-NH2. The peptide shows close structural similarities to other nonmammalian (3-4 amino acid substitutions) and mammalian (5-8 amino acid substitutions) CGRPs, and it contains the two residues Asp14 and Phe15 that seem to be characteristic for CGRP in nonmammalian vertebrates. Cod CGRP (10(-9)-10(-7) M) inhibited the motility of spontaneously active ring preparations from the cod intestine and was significantly (P < 0.05) more potent than rat alpha-CGRP. Neither prostaglandins nor nitric oxide is involved in the inhibitory response produced by cod CGRP, and the lack of effect of tetrodotoxin suggests an action of CGRP on receptors on the intestinal smooth muscle cells. The competitive CGRP antagonist human alpha-CGRP-(8-37) significantly (P < 0.05) reduced the response to cod CGRP. Immunohistochemistry demonstrated CGRP-immunoreactive neurons intrinsic to the intestine, and a dense innervation with immunoreactive nerve fibers was observed in the myenteric plexus and the circular muscle layer. Myotomy studies show that CGRP-containing nerves project orally and anally in the myenteric plexus, whereas nerve fibers in the circular muscle layer project mainly anally, indicating a role for CGRP in descending inhibitory pathways of the cod intestine.

Peptidergic control of gastrointestinal blood flow in the estuarine crocodile, Crocodylus porosus

Peptidergic mechanisms influencing the resistance of the gastrointestinal vascular bed of the estuarine crocodile, Crocodylus porosus, were investigated. The gut was perfused in situ via the mesenteric and the celiac arteries, and the effects of different neuropeptides were tested using bolus injections. Effects on vascular resistance were recorded as changes in inflow pressures. Peptides found in sensory neurons [substance P, neurokinin A, and calcitonin gene-related peptide (CGRP)] all caused significant relaxation of the celiac vascular bed, as did vasoactive intestinal polypeptide (VIP), another well-known vasodilator. Except for VIP, the peptides also induced transitory gut contractions. Somatostatin and neuropeptide Y (NPY), which coexist in adrenergic neurons of the C. porosus, induced vasoconstriction in the celiac vascular bed without affecting the gut motility. Galanin caused vasoconstriction and occasionally activated the gut wall. To elucidate direct effects on individual vessels, the different peptides were tested on isolated ring preparations of the mesenteric and celiac arteries. Only CGRP and VIP relaxed the epinephrine-precontracted celiac artery, whereas the effects on the mesenteric artery were variable. Somatostatin and NPY did not affect the resting tonus of these vessels, but somatostatin potentiated the epinephrine-induced contraction of the celiac artery. Immunohistochemistry revealed the existence and localization of the above-mentioned peptides in nerve fibers innervating vessels of different sizes in the gut region. These data support the hypothesis of an important role for neuropeptides in the control of the vascular bed of the gastrointestinal tract in C. porosus.

Biased dependency of CD80 versus CD86 in the induction of transcription factors regulating the human IL-2 promoter

In addition to the signals obtained by ligation of the TCR, T cells need additional, co-stimulatory signals to be activated. One such co-stimulatory signal is delivered when CD28 on T cells binds to CD80 or CD86 on antigen-presenting cells (APC). In the present study, we analyzed the ability of CD80 and CD86 to co-stimulate human T cells activated by superantigen. Using the Raji B cell lymphoma, which express similar levels of CD80 and CD86, it was found that T cell proliferation was mainly co-stimulated by CD80. To further characterize the consequences of this biased co-stimulatory dependency, we employed a well-defined system of transfected CHO cells expressing human MHC class II together with CD80, CD86 or CD80 and CD86. Proliferation of freshly prepared CD4+ T cells required the presence of either CD80 or CD86. However, IL-2 production reached only suboptimal levels in the presence of CD86 but optimal levels with CD80. To analyze IL-2 transcriptional activity in CD80 and CD86 co-stimulated T cells we used Jurkat T cells transfected with luciferase reporter gene constructs. CD80 induced higher levels of IL-2 promoter-enhancer activity compared to CD86. Furthermore, the activity of transcription factors regulating the IL-2 promoter-enhancer region including activation protein-1, CD28 response element and nuclear factor kappaB were 4-8 times higher after CD80 compared to CD86 ligation. Our results suggest that the eventual appearance of CD80 on recently activated CD86+ APC is important for the superinduction of IL-2 production and to support vigorous T cell proliferation.

Non-invasive assessment of the atrial cycle length during atrial fibrillation in man: introducing, validating and illustrating a new ECG method

OBJECTIVES

Atrial fibrillation (AF) in man has previously been shown to include a wide variety of atrial activity. Assessment of the characteristics of this arrhythmia with a commonly applicable tool may therefore be important in the choice and evaluation of different therapeutic strategies. As the AF cycle length has been shown to correlate locally with atrial refractoriness and globally with the degree of atrial organization, with, in general, shorter cycle length during apparently random AF compared to more organized AF, we have developed a new method for non-invasive assessment of the AF cycle length using the surface and the esophagus (ESO) ECG.

METHODS AND RESULTS

From the frequency spectrum of the residual ECG, created by suppression of the QRST complexes, the dominant atrial cycle length (DACL) was derived. By comparison with multiple intracardiac simultaneously acquired right and left AF cycle lengths in patients with paroxysmal AF, we found that the DACL in lead V1, ranging from 130 to 185 ms, well represented a spatial average of the right AF cycle lengths, whereas the DACL in the ESO ECG, ranging from 140 to 185 ms, reflected both the right and the left AF cycle length, where the influence from each structure depended on the atrial anatomy of the individual, as determined by MRI. In patients with chronic AF, the method was capable of following changes in the AF cycle length due to administration of D,L-sotalol and 5 min of ECG recording was sufficient for the DACL to be reproducible.

CONCLUSIONS

We conclude that this new non-invasive method, named 'Frequency Analysis of Fibrillatory ECG' (FAF-ECG), is capable of assessing both the magnitude and the dynamics of the atrial fibrillation cycle length in man.

The Ig mutator is dependent on the presence, position, and orientation of the large intron enhancer

Hypermutation at the Ig loci is confined to the area between the promoter and the intronic enhancer, which includes the rearranged variable region gene segment. We identified factors that contribute to the site-specificity at the heavy chain locus. We found that distance from both the promoter and the intronic enhancer is crucial in hypermutation. The presence of the enhancer is required, and, in contrast to its definition for transcriptional activity, its effect is orientation-sensitive.

MHC class II-independent, Vbeta-specific activation of T cells by superantigen mutants fused to anti-tumor Fab fragments: implications for use in treatment of human colon carcinoma

Genetically engineered fusion proteins of the super-antigen staphylococcal enterotoxin A (SEA) and tumor-reactive monoclonal antibodies, C215Fab-SEA and C242Fab-SEA, have been generated and shown to be effective in mediating superantigen-antibody directed cellular cytotoxicity against human carcinoma cells expressing the CA215 or CA242 antigens in an MHC class II-independent manner. In an attempt to reduce the in vivo toxicity of superantigen administration, alanine substitution mutations in SEA at residues F47 and D227 that affect SEA binding to class II molecules have been created and genetically linked to C215Fab or C242Fab. The purpose of this study was to determine whether these Fab-SEA mutant fusion proteins, that have low MHC class II binding affinities, were still able to stimulate human T cells in a Vbeta-specific manner in the presence or absence of MHC class II molecules. The SEA wt- and SEA-D227A-based fusion proteins shared the ability to activate V beta5. 2-, Vbeta6-, Vbeta7-, Vbeta9- and Vbeta18-bearing T cells, whereas Fab-SEA-F47A protein activated only Vbeta6- and Vbeta7-bearing T cells. The fusion of Fab fragments onto SEA wt, SEA-F47A or SEA-D227A had no effect on the Vbeta specificity of these superantigens. Fab fusion proteins containing either SEA wt or SEA mutants were presented, in the absence of class II molecules, by CHO cells transfected with CA215 and CD80 and all induced the expansion of only Vbeta6-, Vbeta7- and Vbeta 18-bearing T cells. Fab-SEA mutant fusion proteins may provide attenuated therapeutic agents that, while still able to specifically target high affinity T cells for MHC class II-independent local tumor killing, will not induce excessive systemic toxicity.

A 5-year prospective clinical study of Astra Tech dental implants supporting fixed bridges or overdentures in the edentulous mandible

In a 5-year prospective clinical study, 155 endosseous implants were installed in the mandible anterior to the mental foramina in 33 edentulous patients (13 males and 20 females). Usually 6 implants were installed for fixed prostheses (FP), 13 patients with 77 implants, and 4 implants for overdentures (OD) with a Dolder bar, 20 patients with 78 implants. At the time of abutment connection 1 implant in 2 patients was found to be loose and removed. However, in both these patients overdentures were successfully placed on the remaining 3 implants. Narrow-beam radiography was used for radiological evaluation. The mean (SD) total marginal bone loss in 5 years was 0.48 (0.38) mm (0.36 (0.22) mm in the FP group and 0.56 (0.45) mm in the OD group). Very few complications were reported during the 5 years, most of them being related to the superstructures. The overall cumulative implant survival rate was 98.7% (100% in the FP group and 97.4% in the OD group). The survival rate of the superstructures was 100%. The present study has demonstrated that Astra Tech implants offer reliable and predictable medium-term support for fixed prostheses and overdentures in the edentulous mandible.

Nitric oxide in the fish gut

Nitric oxide synthase-positive nerve cells have been found in most vertebrate classes and also some invertebrates, indicating an early evolutionary origin for the enzyme and its function as a neurotransmitter. The general distribution and inhibitory effect on motility of nitric oxide in the fish gut agrees well with studies from other vertebrates, but details may vary between species, suggesting variations in function. The coexistence with vasoactive intestinal polypeptide (VIP)/pituitary adenylate cyclase-activating polypeptide (PACAP) suggests a co-function in fish as in mammals, but this remains to be confirmed.

Apoptosis in the rat penis after penile denervation

PURPOSE

Despite the advances in nerve sparing prostatectomy for prostate cancer, some patients develop impotence or subjectively complain of a decrease in penile size. We hypothesized that these clinical observations may be explained by injury to the cavernous nerves resulting in programmed cell death (apoptosis) within the penis. We utilized a rat model of penile denervation in order to demonstrate apoptosis after denervation.

METHODS AND MATERIALS

Fifteen male Sprague Dawley rats underwent abdominal exploration and bilateral cavernous neurotomy. Fifteen sham operations were performed as normal controls. The rats were sacrificed on postoperative day 1,2,3,6, and 10 and their penises were harvested. Messenger RNA was extracted and probed on a northern blot for sulfated glycoprotein-2 (SGP-2). SGP-2 is a gene product reported to be elevated in apoptotic tissues. Separate denervated and sham rats were used for DNA extraction (sacrificed postoperative day #2) in order to demonstrate the internucleosomal DNA fragmentation (laddering) found in apoptotic tissues. In addition, in situ histology was performed with ISEL techniques (in situ end labeling) to stain for apoptotic nuclei in denervated rats.

RESULTS

Northern blot analysis showed a large increase in SGP-2 mRNA expression in the denervated rats with little detected in the sham operated group. DNA extraction studies revealed the presence of internucleosomal DNA fragmentation on agarose gel (a marker for apoptosis) in the denervated group versus intact high molecular weight DNA in the sham rats. In addition, in situ staining of denervated penile erectile tissue demonstrated apoptotic nuclei in the cavernous tissue.

CONCLUSION

Apoptosis of penile erectile tissue occurs after denervation of the rat penis. This has not been previously described in the literature and may offer some explanation at the molecular level concerning the mechanism of impotence and/or decrease in penile size after radical prostatectomy.

Olfactory cues from an oxytocin-injected male rat can reduce energy loss in its cagemates

Rats can recognize the odor of a stressed conspecific and react with stress themselves. Stress mobilizes energy, causing increased core temperatures and energy loss by radiation from the naked tail. Oxytocin administered in high doses (1 mg/kg, s.c.) reduces a rat's tail skin temperature and thereby the radiated energy loss. While administration of this high dose of oxytocin induces sedation low doses induce anxiolysis. This study demonstrates that the cagemates of an oxytocin-treated (1 mg/kg s.c.) rat, which themselves have not received any oxytocin-treatment, show energy conservation, apparent as reduced tail skin temperature. This effect was blocked by olfactory impairment. The temperature reduction in the cagemates probably reflects an oxytocin-mediated olfactorily activated stress inhibitory mechanism.

Single-tooth replacement by osseointegrated Astra Tech dental implants: a 2-year report

This study presents the outcome of single-tooth restorations supported by Astra Tech single-tooth implants followed for 2 years. Forty-seven implants were placed in the same number of patients. Forty-three patients attended the second recall visit, and none of the evaluated implants have been removed. The mean marginal bone loss after 2 years of service was 0.31 (SD = 0.48) mm. Overall, few complications were recorded during the 2-year period, the most frequent of which were loose crowns (7).

Contrast-enhanced radiography by differential absorption, using a laser-produced x-ray source

RATIONALE AND OBJECTIVES

The authors evaluate the feasibility of differential imaging of contrast media, with division of individual pixel values obtained from digital images generated by characteristic radiation from a laser-produced plasma, bridging the K-absorption edge of the contrast agent.

METHODS

Laser pulses from an ultrashort-pulse terawatt laser system were focused onto gadolinium and tantalum targets, creating a plasma from which characteristic radiation and Bremsstrahlung was emitted. The elements of the target were selected so the characteristic emission lines of one of the elements were below the K edge of the contrast agent and the emission lines of the other element above. A phantom with gadolinium and other elements in various concentrations was examined. One radiographic exposure was made using a gadolinium target source and a subsequent exposure using a tantalum source. Both images were recorded digitally and the transmission ratios calculated by division of the individual pixel values.

RESULTS

When viewed separately, the two images of the test phantom appeared similar. In the differential image, only the gadolinium solutions were bright, reflecting a difference in attenuation between the two exposures.

CONCLUSIONS

Element-specific radiographs can be obtained by differential imaging. When fully explored, the technique may allow for contrast-enhanced radiography with increased sensitivity and decreased contrast dose.

Mutations in the MHC class II binding domains of staphylococcal enterotoxin A differentially affect T cell receptor Vbeta specificity

C-terminal residues of staphylococcal enterotoxin A (SEA), including H187, D225, and D227, are involved in moderate affinity binding to MHC class II beta-chain, whereas N-terminal residues, including F47, are involved in low affinity binding to MHC class II alpha-chain. The effect of alanine substitutions at residues D227 or F47 on induction of T cell proliferation and the expansion of specific TCR Vbeta families was determined. SEA wild type specifically activated T cells expressing Vbeta1, Vbeta5.2, Vbeta6, Vbeta7, Vbeta9, Vbeta18, and Vbeta22. Although SEA-D227A exhibited substantially reduced mitogenicity compared with SEA wild type, it expanded the same Vbeta-bearing T cells, except those expressing Vbeta1. By contrast, SEA-F47A, which was slightly less mitogenic than SEA wild type, induced expansion only of T cells expressing Vbeta6, Vbeta7, and to a lesser extent Vbeta22. Therefore, specific mutations affecting either MHC class II alpha or beta binding sites differentially affect the Vbeta specificity of this superantigen. The lack of expansion in four of seven Vbeta families by SEA-F47A suggests that the class II alpha binding site may position SEA on the MHC class II molecules in an appropriate conformation for interaction with certain Vbeta elements.

Mutations in the MHC class II binding domains of staphylococcal enterotoxin A differentially affect T cell receptor Vbeta specificity

C-terminal residues of staphylococcal enterotoxin A (SEA), including H187, D225, and D227, are involved in moderate affinity binding to MHC class II beta-chain, whereas N-terminal residues, including F47, are involved in low affinity binding to MHC class II alpha-chain. The effect of alanine substitutions at residues D227 or F47 on induction of T cell proliferation and the expansion of specific TCR Vbeta families was determined. SEA wild type specifically activated T cells expressing Vbeta1, Vbeta5.2, Vbeta6, Vbeta7, Vbeta9, Vbeta18, and Vbeta22. Although SEA-D227A exhibited substantially reduced mitogenicity compared with SEA wild type, it expanded the same Vbeta-bearing T cells, except those expressing Vbeta1. By contrast, SEA-F47A, which was slightly less mitogenic than SEA wild type, induced expansion only of T cells expressing Vbeta6, Vbeta7, and to a lesser extent Vbeta22. Therefore, specific mutations affecting either MHC class II alpha or beta binding sites differentially affect the Vbeta specificity of this superantigen. The lack of expansion in four of seven Vbeta families by SEA-F47A suggests that the class II alpha binding site may position SEA on the MHC class II molecules in an appropriate conformation for interaction with certain Vbeta elements.

Regulation of superantigen-induced T cell activation in the absence and the presence of MHC class II

To study MHC class II-dependent and -independent SAg2 activation and the relative importance of CD80/CD28 costimulation, staphylococcal enterotoxin A (SEA) was presented to T cells as a fusion protein containing the Fab fragment of an mAb directed against the CA215 glycoprotein. Chinese hamster ovary (CHO) cells transfected with HLA-DR4, CA215, and CD80, individually or in combinations, were used as presenting cells. A strong T cell proliferation was obtained when C215Fab-SEA fusion proteins were presented by CHO-DR/CD80 or CHO-CA215/CD80 double transfectants, whereas only low levels of proliferation were seen in the absence of CD80. Large amounts of IL-2, IFN-gamma, and TNF were produced in addition to an increase in IL-2 mRNA as a result of CD80 costimulation. Only approximately 50% of the SEA-reactive T cells responded by expression of IL-2 receptor chains and by blast formation when activated with SEA in the absence of MHC class II. Reverse transcription-PCR-assisted repertoire analysis of SEA-reactive TCR V beta families showed that the CA215-dependent activation involved an expansion of fewer TCR V beta families compared with MHC class II-dependent activation. One-half of the six analyzed TCR V beta families were expanded independently of class II. This indicates that MHC class II has only a partial influence on the TCR V beta repertoire imprinted by SAg. This finding redefines the role of MHC class II in SAg presentation. It is suggested that MHC class II molecules are selected as SAg-binding molecules mainly as a suitable targeting receptor for professional APC expressing costimulatory molecules such as CD80 and CD86.

Regulation of superantigen-induced T cell activation in the absence and the presence of MHC class II

To study MHC class II-dependent and -independent SAg2 activation and the relative importance of CD80/CD28 costimulation, staphylococcal enterotoxin A (SEA) was presented to T cells as a fusion protein containing the Fab fragment of an mAb directed against the CA215 glycoprotein. Chinese hamster ovary (CHO) cells transfected with HLA-DR4, CA215, and CD80, individually or in combinations, were used as presenting cells. A strong T cell proliferation was obtained when C215Fab-SEA fusion proteins were presented by CHO-DR/CD80 or CHO-CA215/CD80 double transfectants, whereas only low levels of proliferation were seen in the absence of CD80. Large amounts of IL-2, IFN-gamma, and TNF were produced in addition to an increase in IL-2 mRNA as a result of CD80 costimulation. Only approximately 50% of the SEA-reactive T cells responded by expression of IL-2 receptor chains and by blast formation when activated with SEA in the absence of MHC class II. Reverse transcription-PCR-assisted repertoire analysis of SEA-reactive TCR V beta families showed that the CA215-dependent activation involved an expansion of fewer TCR V beta families compared with MHC class II-dependent activation. One-half of the six analyzed TCR V beta families were expanded independently of class II. This indicates that MHC class II has only a partial influence on the TCR V beta repertoire imprinted by SAg. This finding redefines the role of MHC class II in SAg presentation. It is suggested that MHC class II molecules are selected as SAg-binding molecules mainly as a suitable targeting receptor for professional APC expressing costimulatory molecules such as CD80 and CD86.

Involvement of nitric oxide in inhibitory innervation of urinary bladder of Atlantic cod, Gadus morhua

The aim of this study was to investigate the involvement of nitric oxide (NO) in the nonadrenergic, noncholinergic (NANC) relaxation of the urinary bladder of the Atlantic cod, Gadus morhua. NADPH diaphorase-reactive nerve cells, presumed to be able to produce NO, were found in the vesicular nerve. The cells occurred alone and in ganglia together with stained and unstained cells. The effect of inhibitors of NO synthesis on the relaxation was examined in vitro in isolated muscle preparations. NG-nitro-L-arginine methyl ester (10(-4) M) and NG-nitro-L-arginine (L-NNA; 10(-4) M) decreased the electrically induced relaxation to 32 +/- 6 (n = 8) and 28 +/- 6% (n = 8) of the control, respectively. L-Arginine (10(-3) M) increased the relaxation to 152 +/- 24% (n = 8), without affecting the inhibition by L-NNA. The beta-adrenoceptor antagonist propranolol together with L-arginine analogues abolished the relaxation in 7 of 11 preparations. The NO donor sodium nitroprusside (NaNP) caused a concentration-dependent relaxation of the bladder, with a maximal effect obtained at 10(-4) M. LY-83583 (10(-5) M), a guanylate cyclase inhibitor, decreased both the electrically (n = 8) and the NaNP (10(-6) M, n = 9)-induced relaxation to 69 +/- 5 and 20 +/- 4% of the control, respectively. Together these findings suggest that NO is involved in the NANC regulation of the motility of the urinary bladder of the Atlantic cod.

Distribution of neurons reactive for NADPH-diaphorase in the branchial nerves of a teleost fish, Gadus morhua

The NADPH-diaphorase reaction was used to determine the distribution of postganglionic autonomic neurons in the branches of the glossopharyngeal and vagus nerves supplying the gill arches of the cod fish, Gadus morhua. Neurons were common in major nerve trunks in all gill arches, especially in the post-trematic rami of the branchial nerves. From about 55% to more than 85% of the neurons in any branchial nerve were reactive for NADPH-diaphorase. The results suggest that the presence of NADPH-diaphorase, and presumably the ability to synthesise nitric oxide, have been a property of cranial parasympathetic neurons from early in the evolution of the vertebrates.

Commitment and maintenance of the alpha beta and gamma delta T cell lineages

We have generated transgenic mice using a rearranged, functional TCR-gamma gene that lacks the C gamma 1 3' silencer element, together with a TCR-delta cDNA construct designed for expression in lymphoid cells. All transgenic mice that descended from nine founders expressed alpha beta T cells and elevated levels of gamma delta T cells at various ratios. This observation does not support the proposal that alpha beta T cells are generated from T precursors in which C gamma 1 genes have been repressed via the cis-acting 3' silencer element, but it supports the idea that lineage commitment occurs independently of TCR gene expression. In seven transgenic lines, despite the absence of the 3' C gamma 1 silencer on the gamma transgene, the transgenic TCR is expressed only in gamma delta and not in alpha beta T cells. In the other two lines, in addition to T cells that express either the alpha beta or gamma delta TCR, a substantial fraction of T cells expresses both alpha beta and gamma delta TCR. These two lines also carry the highest number of copies of TCR-gamma transgene. However, in general, there is no correlation between the copy number of the gamma transgene and the fraction of T cells expressing the gamma delta TCR. The implications of these data are discussed.

Basic research

Basic research is currently investigating the molecular cascade associated with bladder cancer development. Many new findings are potential leads towards the improvement of the diagnosis and prognosis of this disease. Special care, however, should be taken in the design of protocols for clinical evaluation of the value of these markers. Some initial guidelines have been put forward in this report.

Commitment and maintenance of the alpha beta and gamma delta T cell lineages

We have generated transgenic mice using a rearranged, functional TCR-gamma gene that lacks the C gamma 1 3' silencer element, together with a TCR-delta cDNA construct designed for expression in lymphoid cells. All transgenic mice that descended from nine founders expressed alpha beta T cells and elevated levels of gamma delta T cells at various ratios. This observation does not support the proposal that alpha beta T cells are generated from T precursors in which C gamma 1 genes have been repressed via the cis-acting 3' silencer element, but it supports the idea that lineage commitment occurs independently of TCR gene expression. In seven transgenic lines, despite the absence of the 3' C gamma 1 silencer on the gamma transgene, the transgenic TCR is expressed only in gamma delta and not in alpha beta T cells. In the other two lines, in addition to T cells that express either the alpha beta or gamma delta TCR, a substantial fraction of T cells expresses both alpha beta and gamma delta TCR. These two lines also carry the highest number of copies of TCR-gamma transgene. However, in general, there is no correlation between the copy number of the gamma transgene and the fraction of T cells expressing the gamma delta TCR. The implications of these data are discussed.

Pharmacokinetics and tissue distribution of cisplatin in nude mice: platinum levels and cisplatin-DNA adducts

The pharmacokinetics of platinum (Pt) and cisplatin (CDDP)-DNA adducts were studied in nude mice after single-dose CDDP treatments. Whole blood, serum, kidney, lever, testis, brain, and tumor were collected at different intervals after injection of CDP at different dose levels. Pt was measured with flameless atomic absorption spectrometry (FAAS) or adsorptive voltammetry (AdV) and CDDP-DNA adducts with quantitative immunohistochemistry. The drug was immediately absorbed into the blood circulation (peak serum Pt levels were reached within 5 min) after i.p. CDDP administration, and distribution into most tissues also occurred rapidly (tissue Pt levels peaked at 15 min). With a sampling period of 7 days there was a biphasic elimination of Pt from blood, serum, and tissues. In the brain the pharmacokinetics differed with a gradual accumulation of Pt occurring during the 1st week. Formation of CDDP-DNA adducts in tissues was a slower process, with maximal levels being achieved at between 30 min and 4 h after drug administration, followed by a steady state lasting for at least 24 h. Each tissue type had its specific immunohistochemical staining pattern of adducts. With escalating CDDP doses there was a linear, or almost linear, increase in Pt concentrations and CDDP-DNA adduct levels in all sample types examined. These results suggest that a fair estimation of the amount of drug in tumor and normal tissues can be made from analysis of serum Pt at a fixed time point after a single dose of CDDP.