Molecular and physiologic changes in the SpaceX Inspiration4 civilian crew.

Human spaceflight has historically been managed by government agencies, such as the NASA Twins Study1, but new commercial spaceflight opportunities have opened spaceflight to a broader population. In 2021, the SpaceX Inspiration4 mission launched the first-ever all civilian crew to low Earth orbit, which included the youngest American astronaut (age 29), novel in-flight experimental technologies (handheld ultrasound imaging, smartwatch wearables, and immune profiling), ocular alignment measurements, and new protocols for in-depth, multi-omic molecular and cellular profiling. Here we report the primary findings from the 3-day spaceflight mission, which induced a broad range of physiological and stress responses, neurovestibular changes indexed by ocular misalignment, and altered neurocognitive functioning, some of which match long-term spaceflight2, but almost all of which did not differ from baseline (pre-flight) after return to Earth. Overall, these preliminary civilian spaceflight data suggest that short-duration missions do not pose a significant health risk, and moreover present a rich opportunity to measure the earliest phases of adaptation to spaceflight in the human body at anatomical, cellular, physiologic, and cognitive levels. Finally, these methods and results lay the foundation for an open, rapidly expanding biomedical database for astronauts3, which can inform countermeasure development for both private and government-sponsored space missions.

Direct Comparison of Epifluorescence and Immunostaining for Assessing Viral Mediated Gene Expression in the Primate Brain.

Viral vector technologies are commonly used in neuroscience research to understand and manipulate neural circuits, but successful applications of these technologies in non-human primate models have been inconsistent. An essential component to improve these technologies is an impartial and accurate assessment of the effectiveness of different viral constructs in the primate brain. We tested a diverse array of viral vectors delivered to the brain and extraocular muscles of macaques and compared three methods for histological assessment of viral-mediated fluorescent transgene expression: epifluorescence (Epi), immunofluorescence (IF), and immunohistochemistry (IHC). Importantly, IF and IHC identified a greater number of transduced neurons compared to Epi. Furthermore, IF and IHC reliably provided enhanced visualization of transgene in most cellular compartments (i.e., dendritic, axonal, and terminal fields), whereas the degree of labeling provided by Epi was inconsistent and predominantly restricted to somas and apical dendrites. Because Epi signals are unamplified (in contrast to IF and IHC), Epi may provide a more veridical assessment for the amount of accumulated transgene and, thus, the potential to chemogenetically or optogenetically manipulate neuronal activity. The comparatively weak Epi signals suggest that the current generations of viral constructs, regardless of delivered transgene, are not optimized for primates. This reinforces an emerging viewpoint that viral vectors tailored for the primate brain are necessary for basic research and human gene therapy.

The Psychiatric Cell Map Initiative: A Convergent Systems Biological Approach to Illuminating Key Molecular Pathways in Neuropsychiatric Disorders.

Although gene discovery in neuropsychiatric disorders, including autism spectrum disorder, intellectual disability, epilepsy, schizophrenia, and Tourette disorder, has accelerated, resulting in a large number of molecular clues, it has proven difficult to generate specific hypotheses without the corresponding datasets at the protein complex and functional pathway level. Here, we describe one path forward-an initiative aimed at mapping the physical and genetic interaction networks of these conditions and then using these maps to connect the genomic data to neurobiology and, ultimately, the clinic. These efforts will include a team of geneticists, structural biologists, neurobiologists, systems biologists, and clinicians, leveraging a wide array of experimental approaches and creating a collaborative infrastructure necessary for long-term investigation. This initiative will ultimately intersect with parallel studies that focus on other diseases, as there is a significant overlap with genes implicated in cancer, infectious disease, and congenital heart defects.

Is the progression free survival advantage of concurrent gemcitabine plus cisplatin and radiation followed by adjuvant gemcitabine and cisplatin in patients with advanced cervical cancer worth the additional cost? A cost-effectiveness analysis.

OBJECTIVE: The objective of this study is to determine whether concurrent and adjuvant chemoradiation with gemcitabine/cisplatin is cost-effective in patients with stage IIB to IVA cervical cancer. METHODS: A cost-effectiveness model compared two arms of the trial performed by Duenas-Gonzalez et al. [1]: concurrent and adjuvant chemoradiation with gemcitabine/cisplatin (RT/GC+GC) versus concurrent radiation with cisplatin (RT/C). Major adverse events (AEs) and progression free survival (PFS) rates of each arm were incorporated in the model. AEs were defined as any hospitalization including grade 4 anemia, grade 4 neutropenia, and death. Medicare data and literature review were used to estimate costs. Incremental cost-effectiveness ratios (ICERs) per progression-free life-year saved (PF-LYS) were calculated. Sensitivity analyses were performed for pertinent uncertainties. RESULTS: For 10,000 women with locally advanced cervical cancer, the cost of therapy and AEs was $173.9 million (M) for RT/C versus $259.8M for RT/GC+GC. There were 879 additional 3-year progression-free survivors in the RT/GC+GC arm. The ICER for RT/GC+GC was $97,799 per PF-LYS. When the rate of hospitalization was equalized to 4.3%, the ICER for RT/GC+GC exceeded $80,000. The resultant ICER when increasing PFS in the RT/GC+GC arm by 5% was $62,605 per PF-LYS. When the cost of chemotherapy was decreased by 50%, the ICER was below $50,000 at $41,774 per PF-LYS. CONCLUSIONS: Radiation and gemcitabine/cisplatin for patients with stage IIB to IVA cervical cancer are not cost-effective. The increased financial burden of radiation with gemcitabine/cisplatin and associated toxicities appears to outweigh the benefit of increased 3-year PFS and is primarily dependent on chemotherapy drug costs.

Is selective lymphadenectomy more cost-effective than routine lymphadenectomy in patients with endometrial cancer?

OBJECTIVE: The objective of this study is to determine the cost-effectiveness of two strategies in women undergoing surgery for newly diagnosed endometrial cancer. METHODS: A decision analysis model compared two surgical strategies: 1) routine lymphadenectomy independent of intraoperative risk factors or 2) selective lymphadenectomy for women with high or intermediate risk tumors based on intraoperative assessment including tumor grade, depth of invasion, and tumor size. Published data were used to estimate the outcomes of stage, adjuvant therapy, and recurrence. Costs of surgery, radiation, and chemotherapy were estimated using Medicare Current Procedural Technology codes and Physician Fee Schedule. Cost-effectiveness ratios were estimated for each strategy. Sensitivity analyses were performed including an estimate for lymphedema for patients that underwent a lymphadenectomy. RESULTS: For 40,000 women diagnosed annually with endometrial cancer in the United States, the annual cost of selective lymphadenectomy is $1.14 billion compared to $1.02 billion for routine lymphadenectomy. The selective lymphadenectomy strategy cost an additional $123.3 million. Five-year progression-free survival was 85.9% in the routine strategy compared to 79.3% in the selective strategy. Treatment cost $6349 more per survivor in the selective strategy compared to routine strategy ($36,078 vs. $29,729). These results held up under a variety of sensitivity analyses including costs due to lymphedema which were higher in the routine lymphadenectomy strategy compared to the selective lymphadenectomy strategy ($10 million vs. $7.75 million). CONCLUSIONS: A strategy of selective lymphadenectomy based on intraoperative risk factors for patients with endometrial cancer was less cost-effective than routine lymphadenectomy even when the impact of lymphedema was considered.

Effects of prior endoluminal gastroplication on subsequent laparoscopic Nissen fundoplication.

BACKGROUND: The long-term results of endoluminal gastroplication (ELGP) for gastroesophageal reflux disease (GERD) are still under investigation. Laparoscopic Nissen fundoplication (LNF) has unquestionable results in the treatment of GERD and, therefore, it would be unfortunate to compromise this treatment option by performing alternative therapies such as ELGP. METHODS: Six patients underwent ELGP for the treatment of GERD symptoms. After symptoms returned, these patients elected to have a LNF. RESULTS: There was no sign of periesophagitis or intraperitoneal adhesion formation found at hiatal dissection that hindered or complicated the LNF procedure. Recent follow-up has shown that the patient's GERD symptom scores have decreased, as expected after a de novo LNF. CONCLUSION: ELGP does not alter the surgical dissection or results of a subsequent LNF.

Laparoscopic re-operation for failed Heller myotomy.

Laparoscopic Heller myotomy for achalasia has a 10-20% failure rate and may require re-operation to control persistent or recurrent symptoms. We report follow-up of 15 patients who underwent laparoscopic re-operation for failed Heller myotomy. Between 1993 and 2004, 15 patients underwent laparoscopic re-operation for failed Heller myotomy at our center. The mean duration between procedures was 23 months. Follow-up was completed at a mean duration of 30 months in 14 patients (93%) via a telephone questionnaire. Our overall failure rate for primary surgery (n = 106) was 5.6%. The mechanisms of failure were incomplete myotomy (33%), myotomy fibrosis (27%), fundoplication disruption (13%), too tight fundoplication (7%) and a combination of myotomy fibrosis and incomplete myotomy (20%). Significant symptom improvement was observed with postoperative symptom resolution seen in 71% of patients with dysphagia, 89% for regurgitation, 58% for heartburn and 40% for chest pain. Fifty percent reported excellent results and 79% would recommend the procedure to a friend. Subsequent dilations were performed in four patients (29%). Two patients required conversion to open surgery (13%). Three patients (20%) failed the re-operation and required further revisional surgery. Complications included intraoperative perforation in three (none of which resulted in postoperative morbidity) and a pneumothorax in one patient. Prior endoscopic therapies (pneumatic dilation or Botulinum toxin) were not associated with poor results. Laparoscopic re-operation for failed Heller myotomy is feasible and results are encouraging.

Sub-diaphragmatic fascia: role in the recurrence of hiatal hernias.

One of the most common causes of a failed Nissen fundoplication is disruption of the crural repair. We investigated the thickness of the subdiaphragmatic fascia overlying the right and left limb of the right crus in cadavers to determine any difference. Sub-diaphragmatic fascia specimens were obtained from three sites adjacent to the hiatus in 20 preserved cadavers. One square centimeter of fascia was excised 3 cm from the arch of the hiatus on each side and approximately 2-3 mm from the edge of the hiatal opening (labeled RL and LPL). A third sample was taken 1 cm from the arch of the hiatus on the left side (labeled LAL). The thickness of these tissues was measured. The mean tissue thickness of RL, LPL and LAL were 0.22 mm, 0.23 mm and 0.4 mm, respectively. There was no difference in tissue thickness between the lower specimens on both sides (RL vs. LPL); however, LAL was significantly thicker than both RL and LPL (P < 0.05). The thickness of the subdiaphragmatic fascia overlying the right and left limb of the right crus does not differ significantly in the region used for crus closure during antireflux surgery; however, the fascia on the left is thicker anteriorly.

Consequences of elevated homocysteine during embryonic development and possible modes of action.

Elevated maternal homocysteine (Hcys) is a well-established risk factor for embryonic toxicity and the development of congenital defects, particularly neural tube closure defects and neurocristopathies. The mechanisms responsible are unclear but early work has focused on the role of folate metabolism because these defects are greatly reduced by folate supplementation. As a consequence, elevated Hcys is often looked upon as being an indirect consequence of faulty folate metabolism, although more recent studies show Hcys may act directly as a teratogen. Because Hcys is at the crossroads of protein and DNA metabolism, has a propensity to chemically modify proteins directly, can generate free radicals, and even perturb ligand binding to certain receptors, the developmental processes Hcys can potentially disturb are enumerable. But in recent years, investigators have begun identifying cellular and molecular targets for the direct action of Hcys. While elevating Hcys can alter a myriad of basic cellular activities needed for normal development, our current understanding as to the specific etiological mechanisms responsible for congenital defects is very speculative. Here we provide an overview of what is currently known regarding the toxicity and teratogenicity of elevated Hcys during embryonic development, paying particular attention to neural tube and neural crest cell morphogenesis.

Necrotizing infection of the face secondary to intranasal impaction of "crack" cocaine.

"Crack" is a crystalline form of cocaine that is readily available and sold in the form of small granules. The authors report a unique case of forced intranasal impaction of crack cocaine with subsequent extensive necrosis of the nose and upper lip accompanied by a necrotizing infection of the subcutaneous soft tissue of the cheeks, forehead, and temporal regions. The treatment of extensive facial necrosis resulting from infection and ischemia centers around the early diagnosis of the infectious process, prompt and aggressive surgical debridement, and the administration of broad-spectrum antibiotics.

Gastric effects of the CCK-B/gastrin receptor ligand CI-988 in cynomolgus monkeys.

We have previously demonstrated that the CCK-B/gastrin receptor ligand CI-988 induces gastric gland degeneration and atrophy in cynomolgus monkeys, an effect consistent with gastrin receptor antagonism and inhibition of gastrin's trophic effects on oxyntic mucosa. However, gastrin receptor ligands of the dipeptoid chemical series to which CI-988 belongs have been reported to act as agonists or antagonists towards gastrin-related events, depending on the animal model and the functional endpoint examined. To investigate further these apparently conflicting data, basal gastric acid secretion was monitored acutely in conscious monkeys given CI-988 orally at 10 mg/kg or intravenously at 0.01 mumol/kg/hr and histological changes in gastric mucosa were evaluated in monkeys given CI-988 orally at 5, 25 or 75 mg/kg/day for 4 weeks. Degeneration and atrophy of gastric glands occurred at 25 and 75 mg/kg with statistically significant decrements in gastric mucosal height at 75 mg/kg. In addition, CI-988 stimulated gastric acid secretion when given either orally or intravenously. Co-administration of the structurally unrelated CCK-B/gastrin antagonist L-365,260 completely blocked CI-988-stimulated acid secretion, confirming that CI-988's agonist effect on acid secretion is mediated by the gastrin receptor. Assuming that gastric mucosal degeneration is the result of inhibition of gastrin's trophic activity, CI-988 appears to induce paradoxical agonist and antagonist gastrin-receptor mediated effects.

Gastric gland degeneration induced in monkeys by the CCK-B/gastrin receptor antagonist CI-988.

Gastric effects of subchronic treatment with the cholecystokinin-B (CCK-B)/gastrin receptor antagonist CI-988 were investigated in cynomolgus monkeys. In preliminary range-finding studies, CI-988 was given orally to 1 monkey per sex for 14 days at doses of 50, 100, 200, and 500 mg/kg/day. Subchronic studies of CI-988 were subsequently conducted using 5 monkeys per sex at doses of 0, 5, 25, and 75 mg/kg for 4 or 13 wk. High-dose monkeys were dosed initially at 100 mg/kg, but the dose was not well tolerated and was decreased to 75 mg/kg after 8 days of treatment. One male monkey at 75 mg/kg was euthanatized in extremis on day 23. In the range-finding study, minimal to moderate, multifocal to diffuse degeneration of gastric glands, primarily in the fundic region, was observed at 100 mg/kg and above, with frank gastric mucosal atrophy occurring at 200 and 500 mg/kg. Minimal to mild gastric gland degeneration was also observed in the subchronic study after 4 wk at 25 and 75 mg/kg, but histopathologic gastric changes were remarkably absent after 13 wk. Mucosal height in the stomach fundus was decreased 19.8% in 75-mg/kg males at week 4, and although gastric mucosa appeared histologically normal after 13 wk, mucosal height remained 28.6% less than that of controls. In females at 75 mg/kg, fundic mucosal height was decreased 7% and 5% at weeks 4 and 13, respectively, but decreases were not statistically significant. Mean serum gastrin concentrations were increased 10-fold in males only after 4 wk at 75 mg/kg, but were comparable to controls during week 13. CI-988-induced gastric gland degeneration is consistent with antagonism of gastrin's trophic activity toward gastric mucosa. Notwithstanding decrements in gastric mucosal height, disappearance of mild histopathologic findings despite continued treatment with the ligand suggests some degree of adaptation to subchronic CCK-B/gastrin inhibition, although the mechanism of accommodation has yet to be delineated.

High-performance computing, high-speed networks, and configurable computing environments: progress toward fully distributed computing.

The next several years will see the maturing of a collection of technologies that will enable fully and transparently distributed computing environments. Networks will be used to configure independent computing, storage, and I/O elements into "virtual systems" that are optimal for solving a particular problem. This environment will make the most powerful computing systems those that are logically assembled from network-based components and will also make those systems available to a widespread audience. Anticipating that the necessary technology and communications infrastructure will be available in the next 3 to 5 years, we are developing and demonstrating prototype applications that test and exercise the currently available elements of this configurable environment. The Lawrence Berkeley Laboratory (LBL) Information and Computing Sciences and Research Medicine Divisions have collaborated with the Pittsburgh Supercomputer Center to demonstrate one distributed application that illuminates the issues and potential of using networks to configure virtual systems. This application allows the interactive visualization of large three-dimensional (3D) scalar fields (voxel data sets) by using a network-based configuration of heterogeneous supercomputers and workstations. The specific test case is visualization of 3D magnetic resonance imaging (MRI) data. The virtual system architecture consists of a Connection Machine-2 (CM-2) that performs surface reconstruction from the voxel data, a Cray Y-MP that renders the resulting geometric data into an image, and a workstation that provides the display of the image and the user interface for specifying the parameters for the geometry generation and 3D viewing. These three elements are configured into a virtual system by using several different network technologies. This paper reviews the current status of the software, hardware, and communications technologies that are needed to enable this configurable environment. These interdependent technologies include: (1) user interface and application program construction methodologies, (2) the interprocess communication (IPC) mechanisms used to connect the software modules of the application, (3) the network protocols and interface hardware used by the IPC for communicating between modules running on separate and independent computing system elements, (4) the telecommunications infrastructure that provides the low-level data transfer functions for the networks that connect the geographically distributed elements used by the application, and (5) the nature of the functional elements that will be connected to form virtual systems.

Protein adsorption from human plasma is reduced on phospholipid polymers.

Protein adsorption from human plasma was investigated on phospholipid polymers, poly (2-methacryloyloxyethyl phosphorylcholine (MPC)-co-n-butyl methacrylate (BMA) or glass by radioimmunoassay and immunogold labeling techniques. In the present studies the focus was to determine the composition and distribution of proteins at the surface of these materials after contact with human blood plasma. On all materials, protein adsorption was detected and included identification of albumin, IgG, fibrinogen, fibronectin, Hageman factor (factor XII), factor VIII/von Willebrand factor, high-molecular-weight kininogen (HMWK) and the complement protein C5. The amount of protein adsorbed decreased with an increase in the MPC composition and appeared to adsorb to the surfaces in a uniform and evenly distributed manner. Therefore, we suggest that MPC moieties play an important role in suppression of protein adsorption. From these findings, it is concluded that the reduction of protein adsorption at the blood contacting surface of phospholipid polymers may result in the inhibition of thrombus formation.

Somatotopic distribution of corneal afferent neurons in the guinea pig trigeminal ganglion.

The size and somatotopic distribution of corneal afferent neurons in the guinea pig trigeminal ganglion were determined using a retrograde axonal tracing technique. Wheat germ agglutinin-horseradish peroxidase (WGA-HRP) was applied to the central cornea of the guinea pig and the animals were perfusion-fixed 48 h later. In addition, a preliminary study examined corneal afferent neurons in two animals latently infected with the herpes simplex virus by corneal inoculation. The majority of WGA-HRP-labelled neurons were located in the ophthalmic division of the ipsilateral ganglion. A clear dorsoventral somatotopic arrangement of labelled corneal afferent neurons was noted. The size of the neurons averaged 23 microns and the number of cells per ganglion averaged 205. By contrast, the number of labelled neurons in latently infected ganglia averaged less than 50. No size or morphological distinctions could be made between neurons from uninfected or latently infected ganglia. The results of this study have provided for the first time the precise location and somata diameter of primary afferent corneal neurons within the guinea pig trigeminal ganglion.

Adsorption of Hageman factor (factor XII) and other human plasma proteins to biomedical polymers.

Protein adsorption to surfaces occurs whenever blood comes into contact with biomaterials, prosthetic devices, and artificial organs. The plasma protein Hageman factor (factor XII) present at the interface between blood and foreign surfaces can be qualitatively and quantitatively detected after in vitro perfusion of anticoagulated human blood through important biomedical polymers. We have determined protein adsorption by a modified radioimmunoassay and by scanning electron microscopy using immunogold labeling techniques. The materials used included vascular graft materials (Dacron and expanded polytetrafluoroethylene) and the National Heart, Lung, and Blood Institute-Devices and Technology Branch reference materials polydimethylsiloxane, polyethylene, and silicone rubber. Factor VIII-von Willebrand factor, another trace plasma protein, and other plasma proteins such as fibrinogen, immunoglobulin G, albumin, fibronectin, and hemoglobin were also detected at the blood-contacting surface. At physiologic flow rates, the adsorption of these proteins from the circulating blood to the surface of these materials appears to be a function of time, with certain materials, as well as of the physical and chemical characteristics of the material surface. Hageman factor adsorption to surfaces, quantified under static conditions, occurs at nanogram concentrations. These data suggest that trace proteins, such as those important in the activation of the coagulation cascade, can significantly affect the blood compatibility or thrombogenicity of an implanted device.

Sympathetic innervation of the supratentorial dura mater of the rat.

The origin, density, and distribution of sympathetic nerve fibers in the supratentorial dura mater of the rat were examined in detail in the current study by using wheat germ agglutinin horseradish peroxidase (WGA-HRP) retrograde tracing procedures, glyoxylic acid-induced fluorescence, and dopamine beta-hydroxylase (DBH) immunocytochemical staining of dural whole mount preparations. Application of WGA-HRP to the superior sagittal sinus and adjacent areas of the supratentorial dura mater labeled numerous neurons in each of the left and right superior cervical ganglia. Glyoxylic acid and DBH immunocytochemical staining of fixed dural whole mount preparations revealed prominent plexuses of sympathetic nerves about the middle meningeal artery and its branches, about the superior sagittal and transverse sinuses, and "free" within the dura mater, i.e., apparently unassociated with any vasculature. Significantly, in all of these areas, the density of sympathetic innervation revealed in this study was considerably greater than that previously demonstrated by other workers. An impressive population of mast cells also was observed within the dura mater of the glyoxylic acid-treated preparations. The majority of these cells were perivascular; however, a significant number were also present within the dura unrelated to the vasculature, and occasional cells were seen in close apposition to fluorescent sympathetic nerve fibers. Taken together, the identification of a robust sympathetic plexus and prominent mast cell population associated with a dura mater that also receives significant sensory projections from the trigeminal system raises interest regarding the functional interactions of these elements. These observations warrant further consideration regarding their role in the pathogenesis of vascular headache and head pain.

Rat liver immuno-ultrastructural localization of the specific (4-5S) 3-methylcholanthrene-binding protein; evidence for its involvement as a receptor protein in cytochrome P-4501A1 induction.

Two major specific carcinogen-binding proteins are thought to be involved in the regulation of hepatic cytochrome P-4501A1 induction in response to polycyclic aromatic hydrocarbons. We have raised both mono- and polyclonal antibodies which specifically interact with one of these proteins, the 4-5S-specific binding protein. Antibody binding was found to both the specific (4-5S) 3-methylcholanthrene (3MC) binding activity present in rat hepatic cytosol (as quantified on sucrose gradients or by Sephacryl S-300 gel filtration chromatography) and to the purified 39,000-dalton protein previously reported as the specific 3MC-binding protein (determined by Western blot analyses). No immunoreactivity was observed to cytosolic proteins in the region of 70,000 or 95,000 daltons (i.e. corresponding to the Ah receptor). We have used Western blot analyses and immunostaining of cryostat sections to demonstrate that the 4-5S-specific binding protein is present predominantly in the cytoplasm but also (at lower concentration) in the nuclei of untreated Wistar rat hepatocytes. Electron micrographs of immunostained sections indicate that, following exposure to 3MC, the concentration of specific binding proteins in the nucleus increases and this is assumed to be due to translocation of specific binding protein-3MC complexes from the cytoplasm.

A comparison of 32P-postlabelling and immunological methods to examine human lung DNA for benzo[a]pyrene adducts.

Human lung DNA isolated from surgical specimens has been examined for the presence of polycyclic aromatic hydrocarbon-DNA adducts using both 32P-postlabelling and immunological methods. Of 12 samples examined to date, five had detectable amounts of benzo[a]pyrene diol epoxide-DNA adducts (BPDE-DNA) as determined by the enzyme-linked immunosorbent assay (ELISA), after immunoaffinity concentration. Values ranged from 3.5 to 11.5 fmol/mg DNA. When the same group of samples was analysed using the 32P-postlabelling technique, adducts could be detected in all the samples examined. There was generally not a good correspondence between the two methods. The number of adducts measured by 32P-postlabelling ranged from 1-100 per 10(8) nucleotides, which is some two orders of magnitude higher than with the immunological method, indicating that the BPDE-DNA adduct is probably not the major adduct present in these samples.

Topical treatment of mice with benzo[a]pyrene or parenteral administration of benzo[a]pyrene diol epoxide-DNA to rats results in faecal excretion of a putative benzo[a]pyrene diol epoxide-deoxyguanosine adduct.

The administration of [3H]BPDE-DNA, whether by i.p. or i.v. injection, to male Wistar rats resulted in the majority of the radioactivity being recovered in the faeces. Excretion was rapid: within 24 h post-injection, 45% of the applied dose was recovered in the faeces. H.p.l.c. analysis of radioactive material extracted from the faeces by methanol showed that it contained a single component which co-chromatographed with [3H]BPDE-dGuo and which was not affected by treatment with alkaline phosphatase, aryl sulphatase or beta-glucuronidase. To determine if this phenomenon occurs after topical application of BP to a target tissue, such as mouse skin, animals were treated with [3H]BP and their faeces collected. After an extensive extraction procedure involving differential solubility in organic solvents, Sephadex LH-20 chromatography and h.p.l.c., a product was isolated from mice faeces which had characteristics consistent with a [3H]BPDE-dGuo adduct. These findings are discussed in relation to detection of BPDE adducts in human populations.