Spatially-distinct redox conditions and degradation rates following field-scale bioaugmentation for RDX-contaminated groundwater remediation

In situ bioaugmentation for cleanup of an hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX)-contaminated groundwater plume was recently demonstrated. Results of a forced-gradient, field-scale cell transport test with Gordonia sp. KTR9 and Pseudomonas fluorescens strain I-C cells (henceforth "KTR9" and "Strain I-C") showed these strains were transported 13 m downgradient over 1 month. Abundances of xplA and xenB genes, respective indicators of KTR9 and Strain I-C, approached injection well cell densities at 6 m downgradient, whereas gene abundances (and conservative tracer) had begun to increase at 13 m downgradient at test conclusion. In situ push-pull tests were subsequently completed to measure RDX degradation rates in the bioaugmented wells under ambient gradient conditions. Time-series monitoring of RDX, RDX end-products, conservative tracer, xplA and xenB gene copy numbers and XplA and XenB protein abundance were used to assess the efficacy of bioaugmentation and to estimate the apparent first-order RDX degradation rates during each test. A collective evaluation of redox conditions, RDX end-products, varied RDX degradation kinetics, and biomarkers indicated that Strain I-C and KTR9 rapidly degraded RDX. Results showed bioaugmentation is a viable technology for accelerating RDX cleanup in the demonstration site aquifer and may be applicable to other sites. Full-scale implementation considerations are discussed.

Outcome following retrosigmoid microvascular decompression of the facial nerve for hemifacial spasm

This paper evaluates the outcome of retrosigmoid microvascular decompression of the facial nerve in a series of patients suffering from hemifacial spasm who had been referred to the skull-base team (comprising senior authors DAM and DGH). The paper is a retrospective review of 15 patients who underwent retrosigmoid microvascular decompression of the facial nerve at Addenbrooke's Hospital between 1985 and 1995. In this series it was possible to obtain complete resolution of hemifacial spasm in 93.3 per cent of cases in the short term and in 80 per cent in the long term. Twelve patients (80 per cent) were symptom-free post-operatively. Two patients had minor recurrence of symptoms occurring within six months of the procedure. One patient with no identifiable vascular impingement of the facial nerve had no improvement following surgery. Three patients suffered sensorineural hearing loss. Two patients complained of post-operative tinnitus, and transient facial palsy was noted in one patient.

Retrosigmoid microvascular decompression of the facial nerve provides excellent long-term symptom control in a high percentage of patients with hemifacial spasm.

Rapid effector function of circulating NC16A-specific T cells in individuals with mucous membrane pemphigoid

BACKGROUND

Mucous membrane pemphigoid (MMP) is a chronic blistering skin disease frequently associated with circulating autoantibodies directed to a number of antigens including the NC16A region of BP180. NC16A domain-specific T cells have been identified in the blood of individuals with bullous pemphigoid (BP), pemphigoid gestationis and linear IgA disease, but there are no data investigating the potential role for such T cells in the pathogenesis of MMP.

OBJECTIVES

To test the hypothesis that NC16A-specific T cells exist in the peripheral blood of individuals with MMP.

METHODS

We isolated peripheral blood mononuclear cells from 10 patients with MMP, 17 with BP and 10 healthy controls and examined the immunogenicity of overlapping peptides spanning the NC16A domain using interferon (IFN)-gamma enzyme-linked immunospot assay.

RESULTS

Significant IFN-gamma production was observed in response to the NC16A peptides in two of the patients with MMP and two of the patients with BP but in none of the normal controls. These data suggest that in a minority of individuals with MMP, NC16A domain-specific T cells circulate at sufficiently high frequency to be detectable directly ex vivo and to show rapid effector function.

CONCLUSIONS

Overall, these findings are the first to examine the potential role for antigen-specific autoreactive T cells in the pathogenesis of MMP, and confirm that in some individuals the NC16A domain may be an important target antigen.

HLA-B*35-restricted CD8 T cell epitopes in the antigen 85 complex of Mycobacterium tuberculosis

Few target epitopes have been described for human CD8 T lymphocytes in antigens of Mycobacterium tuberculosis. By use of a reverse immunogenetics approach, 23 motif-bearing peptides of the Ag85 complex were tested for binding to HLA-B*35, one of the common B-types in West Africa. Three 9-mer peptides bound with high affinity to HLA-B*3501 and displayed low dissociation rates of peptide-major histocompatibility complexes (MHCs). IC(50) and half-life values of peptide-MHC class I complexes were in the same range as reported earlier for other immunogenic peptides. Immune responses against peptide Ag85C (aa 204-212) WPTLIGLAM were characterized in detail. Peptide-stimulated effector cells were able to kill macrophages infected with M. tuberculosis or bacille Calmette-Guérin. Peptide-specific CD8 T cells could be visualized by using HLA-B*3501 tetramers and were shown to produce interferon-gamma and tumor necrosis factor-alpha. Together with other published epitopes, these peptides can be used to study more closely the role of CD8 T cells in mycobacterial infection and tuberculosis.

Skewed maturation of memory HIV-specific CD8 T lymphocytes

Understanding the lineage differentiation of memory T cells is a central question in immunology. We investigated this issue by analysing the expression of the chemokine receptor CCR7, which defines distinct subsets of naive and memory T lymphocytes with different homing and effector capacities and antiviral immune responses to HIV and cytomegalovirus. Ex vivo analysis of the expression of CD45RA and CCR7 antigens, together with in vitro analysis of the cell-division capacity of different memory CD8+ T-cell populations, identified four subsets of HIV- and CMV-specific CD8+ T lymphocytes, and indicated the following lineage differentiation pattern: CD45RA+ CCR7+ --> CD45RA- CCR7+ --> CD45RA- CCR7- --> CD45RA+ CCR7-. Here we demonstrate through analysis of cell division (predominantly restricted to the CCR7+ CD8+ T-cell subsets) that the differentiation of antigen-specific CD8+ T cells is a two-step process characterized initially by a phase of proliferation largely restricted to the CCR7+ CD8+ cell subsets, followed by a phase of functional maturation encompassing the CCR7- CD8+ cell subsets. The distribution of these populations in HIV- and CMV-specific CD8+ T cells showed that the HIV-specific cell pool was predominantly (70%) composed of pre-terminally differentiated CD45RA- CCR7- cells, whereas the CMV-specific cell pool consisted mainly (50%) of the terminally differentiated CD45RA+ CCR7- cells. These results demonstrate a skewed maturation of HIV-specific memory CD8+ T cells during HIV infection.

T cell receptor usage of virus-specific CD8 cells and recognition of viral mutations during acute and persistent hepatitis B virus infection

T cells specific for a single viral epitope, but using different T cell receptors, should have flexibility in their epitope recognition to protect the infected host against the emergence of viral escape mutants. Therefore, polyclonality of the hepatitis B virus (HBV)-specific cytotoxic T lymphocyte response has been hypothesized to be a major determinant in the control of infection. We analyzed the Vbeta chain composition of the core 18-27-specific CD8 cells in acute and persistently HBV-infected patients using HLA-A2 tetrameric complexes and a panel of Vbeta antibodies. Different T cell receptors were utilized by core 18-27-specific CD8 cells both in patients with acute and chronic infection. The functional ability of these epitope-specific T cells to respond to potential viral mutations was then tested. The polyclonal HBV-specific CD8 response present in patients with acute hepatitis displayed a limited efficiency to recognize mutations introduced within the epitope. The ability of core 18-27-specific CD8 to tolerate epitope mutations was found only during persistent HBV infection. The data suggest that although a clonally heterogeneous CD8 response can be largely inhibited by the occurrence of single epitope mutations in primary HBV infection, preferential selection of T cells able to counteract the emergence of viral mutations can occur during persistent infection.

Human CD8+ CTL specific for the mycobacterial major secreted antigen 85A

The role of CD8(+) CTL in protection against tuberculosis in human disease is unclear. In this study, we stimulated the peripheral blood mononuclear cells of bacillus Calmette-Guérin (BCG)-vaccinated individuals with live Mycobacterium bovis BCG bacilli to establish short-term cell lines and then purified the CD8(+) T cells. A highly sensitive enzyme-linked immunospot (ELISPOT) assay for single cell IFN-gamma release was used to screen CD8(+) T cells with overlapping peptides spanning the mycobacterial major secreted protein, Ag85A. Three peptides consistently induced a high frequency of IFN-gamma responsive CD8(+) T cells, and two HLA-A*0201 binding motifs, P(48-56) and P(242-250), were revealed within the core sequences. CD8(+) T cells responding to the 9-mer epitopes were visualized within fresh blood by ELISPOT using free peptide or by binding of HLA-A*0201 tetrameric complexes. The class I-restricted CD8(+) T cells were potent CTL effector cells that efficiently lysed an HLA-A2-matched monocyte cell line pulsed with peptide as well as autologous macrophages infected with Mycobacterium tuberculosis or recombinant vaccinia virus expressing the whole Ag85A protein. Tetramer assays revealed a 6-fold higher frequency of peptide-specific T cells than IFN-gamma ELISPOT assays, indicating functional heterogeneity within the CD8(+) T cell population. These results demonstrate a previously unrecognized, MHC class I-restricted, CD8(+) CTL response to a major secreted Ag of mycobacteria and supports the use of Ag85A as a candidate vaccine against tuberculosis.

T cell receptor usage of virus-specific CD8 cells and recognition of viral mutations during acute and persistent hepatitis B virus infection

T cells specific for a single viral epitope, but using different T cell receptors, should have flexibility in their epitope recognition to protect the infected host against the emergence of viral escape mutants. Therefore, polyclonality of the hepatitis B virus (HBV)-specific cytotoxic T lymphocyte response has been hypothesized to be a major determinant in the control of infection. We analyzed the Vbeta chain composition of the core 18-27-specific CD8 cells in acute and persistently HBV-infected patients using HLA-A2 tetrameric complexes and a panel of Vbeta antibodies. Different T cell receptors were utilized by core 18-27-specific CD8 cells both in patients with acute and chronic infection. The functional ability of these epitope-specific T cells to respond to potential viral mutations was then tested. The polyclonal HBV-specific CD8 response present in patients with acute hepatitis displayed a limited efficiency to recognize mutations introduced within the epitope. The ability of core 18-27-specific CD8 to tolerate epitope mutations was found only during persistent HBV infection. The data suggest that although a clonally heterogeneous CD8 response can be largely inhibited by the occurrence of single epitope mutations in primary HBV infection, preferential selection of T cells able to counteract the emergence of viral mutations can occur during persistent infection.

Isolation of cytomegalovirus-specific cytotoxic T-lymphocytes from gut-associated lymphoid tissue (GALT) of HIV type 1-infected subjects

Cytomegalovirus (CMV) can be an important opportunistic infection in HIV-1-infected patients, particularly when the CD4+ T-cell count drops below 50 lymphocytes/mm3. CMV-associated disease, including retinitis, pneumonitis, gastroenteritis, and encephalitis, is estimated to affect up to 40% of AIDS patients. We have studied the cellular immune response to CMV in gut-associated lymphoid tissue (GALT) of HIV-1-infected patients. Two patients with chronic diarrhea of unknown etiology were examined by flexible sigmoidoscopy and upper endoscopy. Biopsy specimens were obtained from lymphoid-associated tissue sites in rectum and duodenum. Both patients were seropositive for CMV IgG, but had not been treated with ganciclovir, and neither had clinical signs of CMV disease. Mononuclear cell cultures were established from GALT and blood and assayed for the presence of CMV-specific CD8+ T cells. CD8+ T-cell phenotype and function were assessed by MHC Class I tetramer staining, using an HLA-A*0201 tetramer complex specific for peptide 495-503 (NLVPMVATV) of CMV lower matrix protein pp65, and by a standard 51Cr release assay. CMV pp65-specific cytotoxic lymphocytes (CTL) were detected in GALT and blood MNC from both patients. These results demonstrate that HIV-1-infected subjects seropositive for CMV, but without active CMV gastrointestinal disease, harbor CMV-specific CTL in intestinal lymphoid tissue. This is the first report of isolation of CMV-specific CTL in GALT and will lead to greater understanding of the pathogenesis of CMV disease in human mucosal tissue.

Characterization of HIV-1-specific cytotoxic T lymphocytes expressing the mucosal lymphocyte integrin CD103 in rectal and duodenal lymphoid tissue of HIV-1-infected subjects

Acute HIV-1 infection depletes CD4(+) T cells in gut-associated lymphoid tissue (GALT). The failure of containment of local viral replication, and consequent CD4(+) T cell depletion, might be due to delayed mobilization of effector CD8(+) T cells or absence of functioning HIV-1-specific CD8(+) T cell effectors within GALT. No studies have addressed human intestinal HIV-1-specific CD8(+) T cell functions. We sought to determine whether functional HIV-1-specific CTL were present in GALT and whether the repertoire differed from HIV-1-specific CTL isolated from peripheral blood mononuclear cells. From three HIV-1-infected subjects, we isolated HIV-1-specific CD8(+) T cells expressing the mucosal lymphocyte integrin CD103 from GALT. These antigen-specific effector cells could be expanded in vitro and lysed target cells in an MHC class I-restricted manner. HIV-1-specific CTL could be isolated from both duodenal and rectal GALT sites, indicating that CD8(+) effectors were widespread through GALT tissue. The breadth and antigenic specificities of GALT CTL appeared to differ from those in peripheral blood in some cases. In summary, we found HIV-1-specific CD8(+) effector T cells in GALT, despite HIV-1-induced CD4(+) T cell lymphopenia. This suggests that HIV-1-specific CTL in gut tissue can be maintained with limited CD4(+) T cell help.

The role of virus-specific CD8(+) cells in liver damage and viral control during persistent hepatitis B virus infection

Hepatitis B virus (HBV) is a noncytopathic virus, and the recognition of infected hepatocytes by HBV-specific CD8 cells has been assumed to be the central mechanism causing both liver damage and virus control. To understand the role of cytotoxic T cells in the pathogenesis of HBV infection, we used functional assays that require T cell expansion in vitro and human histocompatibility leukocyte antigen (HLA)-peptide tetramers that allow direct ex vivo quantification of circulating and liver-infiltrating HBV-specific CD8 cells. Two groups of patients with persistent HBV infection were studied: one without liver inflammation and HBV replication, the other with liver inflammation and a high level of HBV replication. Contrary to expectation, a high frequency of intrahepatic HBV-specific CD8 cells was found in the absence of hepatic immunopathology. In contrast, virus-specific T cells were more diluted among liver infiltrates in viremic patients, but their absolute number was similar because of the massive cellular infiltration. Furthermore, inhibition of HBV replication was associated with the presence of a circulating reservoir of CD8(+) cells able to expand after specific virus recognition that was not detectable in highly viremic patients with liver inflammation. These results show that in the presence of an effective HBV-specific CD8 response, inhibition of virus replication can be independent of liver damage. When the HBV-specific CD8 response is unable to control virus replication, it may contribute to liver pathology not only directly but by causing the recruitment of nonvirus-specific T cells.

Direct ex vivo analysis of hepatitis B virus-specific CD8(+) T cells associated with the control of infection

BACKGROUND & AIMS

Cytotoxic T cells have been suggested to be responsible for lysis of hepatitis B virus (HBV)-infected hepatocytes and control of virus infection. The frequency, kinetics, phenotype, and capacity for clonal expansion of circulating HBV-specific CD8 cells were analyzed directly in patients with acute HBV infection to clarify their pathogenetic role.

METHODS

Three HLA-A2 peptide tetramers able to visualize HBV core, envelope, and polymerase epitope-specific cytotoxic T lymphocytes were synthesized and used for flow cytometric analysis of antigen-specific populations.

RESULTS

Tetramer-positive cells specific for the core 18-27 epitope were found at a higher frequency than those specific for polymerase 575-583 and envelope 335-343 epitopes in most patients with acute HBV. The number of HBV-specific CD8 cells was highest during the clinically acute stage of infection and decreased after recovery. These cells expressed an activated phenotype and had an impaired capacity to expand in vitro and to display cytolytic activity in response to peptide stimulation. Recovery of these functions was observed when the frequency of specific CD8 cells decreased, coincident with a progressive decrease in their expression of activation markers.

CONCLUSIONS

This study provides the first ex vivo evidence that the highest frequency of circulating HBV-specific CD8 cells coincides with the clinically acute phase of hepatitis B. These cells exhibit an activated phenotype with limited further proliferative capacity that is restored during recovery.

An outbreak of Escherichia coli O157:H7 infection from unpasteurized commercial apple juice

BACKGROUND

Escherichia coli O157:H7 infections have traditionally been associated with animal products, but outbreaks associated with produce have been reported with increasing frequency. In fall 1996, a small cluster of E. coli O157:H7 infections was epidemiologically linked to a particular brand (brand A) of unpasteurized apple juice.

OBJECTIVE

To define the extent of the outbreak, confirm the source, and determine how the apple juice became contaminated.

DESIGN

Descriptive epidemiologic study and traceback investigation.

SETTING

Western United States and British Columbia, Canada.

PATIENTS

Patients with E. coli O157:H7 infection who were exposed to brand A apple juice.

MEASUREMENTS

Clinical outcome and juice exposure histories of case-patients, pulsed-field gel electrophoresis of case and juice isolates, and juice production practices.

RESULTS

Seventy persons with E. coli O157:H7 infection and exposure to brand A unpasteurized apple juice were identified. Of these persons, 25 (36%) were hospitalized, 14 (20%) developed the hemolytic uremic syndrome, and 1 (1%) died. Recalled apple juice that was produced on 7 October 1996 grew E. coli O157:H7 with a pulsed-field gel electrophoresis pattern indistinguishable from that of case isolates. Apple juice produced on 7 October 1996 accounted for almost all of the cases, and the source of contamination was suspected to be incoming apples. Three lots of apples could explain contamination of the juice: Two lots originated from an orchard frequented by deer that were subsequently shown to carry E. coli O157:H7, and one lot contained decayed apples that had been waxed.

CONCLUSIONS

Standard procedures at a state-of-the-art plant that produced unpasteurized juices were inadequate to eliminate contamination with E. coli O157:H7. This outbreak demonstrated that unpasteurized juices must be considered a potentially hazardous food and led to widespread changes in the fresh juice industry.

Multinational outbreak of Salmonella enterica serotype Newport infections due to contaminated alfalfa sprouts

CONTEXT

In December 1995, reported Salmonella enterica serotype Newport (SN) infections increased sharply in Oregon and British Columbia but not elsewhere in North America. Similar unexplained increases had been noted in 6 other states in the fall of 1995.

OBJECTIVE

To determine the source of the outbreak(s).

DESIGN

Case-control studies, environmental investigations, bacterial subtyping, and surveillance information review.

SETTINGS

Oregon and British Columbia communities (winter 1995-1996) and Georgia, Oklahoma, Pennsylvania, Vermont, Virginia, and West Virginia (fall 1995).

PARTICIPANTS

Oregon and British Columbia residents with culture-confirmed SN infections and onset from December 1, 1995, through February 29, 1996, and healthy community controls.

MAIN OUTCOME MEASURES

Odds ratio (OR) of illness associated with exposures; distribution patterns and culture of alfalfa seeds and sprouts; subtyping of SN isolates.

RESULTS

We identified 133 cases in Oregon and British Columbia; 124 (93%) occurred in patients older than 18 years; 87 (65%) were female. Case patients were more likely than community control subjects to report having eaten alfalfa sprouts in the 5 days preceding illness (41% [17/41] vs 4% [3/75]; OR, 17.0; 95% confidence interval, 4.3-96.0). Case isolates shared a distinctive pulsed-field gel electrophoresis (PFGE) pattern. The SN was grown from seeds and alfalfa sprouts. The distribution of 1 seed lot to multiple growers corresponded to the distribution of cases. Distribution of a second seed lot from the same European wholesaler corresponded to the location of the fall outbreak, which was characterized by a similar demographic profile. The PFGE pattern of fall outbreak isolates and confiscated sprouts and seeds was indistinguishable from the Oregon and British Columbia outbreak and differed from background isolates.

CONCLUSIONS

The SN-contaminated alfalfa seeds were distributed to multiple growers across North America in 1995 and resulted in a protracted international outbreak scattered over many months. Current sprouting methods are inadequate to protect consumers from such events. Alfalfa sprouts may be an elusive but important vehicle for salmonellosis and other enteric infections.

Computer-generated dot maps as an epidemiologic tool: investigating an outbreak of toxoplasmosis

We used computer-generated dot maps to examine the spatial distribution of 94 Toxoplasma gondii infections associated with an outbreak in British Columbia, Canada. The incidence among patients served by one water distribution system was 3.52 times that of patients served by other sources. Acute T. gondii infection among 3, 812 pregnant women was associated with the incriminated distribution system.

Outbreak of toxoplasmosis associated with municipal drinking water. The BC Toxoplasma Investigation Team

BACKGROUND

Outbreaks of toxoplasmosis are recognised infrequently. In March, 1995, a sudden increase of serologically diagnosed cases of acute toxoplasmosis was noted in the Greater Victoria area of British Columbia, Canada. Concurrently, but independently, seven cases of acute toxoplasma retinitis were diagnosed against a background of no cases in the previous 5 years.

METHODS

Cases were defined by serological testing, clinical presentation, and residence in Greater Victoria. A screening programme for women who were or had been pregnant was started. Geographical mapping of cases, and case-control studies of symptomatic cases and of women enrolled in the screening programme were done.

FINDINGS

100 individuals aged 6 to 83 years met the definition for an acute, outbreak-related case. 94 resided in Greater Victoria and six had visited it; 19 had retinitis, 51 had lymphadenopathy, four others had symptoms consistent with toxoplasmosis, seven had other symptoms, 18 were symptom-free, and one would not provide information. 36 (0.9%) of 3812 screened pregnant and postnatal women were cases. Excess cases were not detected outside Greater Victoria and no conventional source of toxoplasmosis was implicated. Mapping studies of cases and of the screened women, and both case-control studies showed significant associations between acute infection and residence in the distribution system of one reservoir supplying water to Greater Victoria (ORs or RRs: 3.53, 3.05, 8.27, and 5.42, respectively). The epidemic curve appeared bimodal, with peaks in December, 1994, and March, 1995, that were preceded by increased rainfall and turbidity in the implicated reservoir.

INTERPRETATION

A municipal water system that uses unfiltered, chloraminated surface water was the likely source of this large community-wide outbreak of toxoplasmosis.

A new method of infant monitoring: for use at home and hospital

AIM

To test a New Zealand originated, designed and funded remote infant heart rate monitor in the home and hospital settings (temporarily named the King Monitor) for accuracy and reliability.

METHODS

The units were pretested using ECG simulators and on infants already being monitored in the neonatal unit. Longer term trials on hospital infants and infants being simultaneously monitored at home were then conducted.

RESULTS

Interference and electrode problems were corrected during the pretesting phase. The unit worked accurately when compared with the standard neonatal heart and respiratory rate monitor in hospital and appeared in some infants to give earlier warning of problems than the standard home apnoea monitor.

CONCLUSION

This simple to use monitor worked reliably and accurately under a wide variety of settings and with varying sized infants. In addition, the lack of direct connection between the infant and the control unit allowed freedom of movement of normal infants around the cot or bassinet. The monitor will require to be adapted for portable use at home and during travel.

Mortality among female registered nurses and school teachers in British Columbia

The mortality profile of female nurses and teachers in British Columbia (BC) was examined using age-standardized proportional mortality ratios (PMRs) calculated for the period 1950-1984. Lowered overall mortality among nurses was seen for degenerative heart disease and for cerebrovascular accidents. Significantly elevated PMR values were observed for cancer of the breast and ovary in nurses of age 20-65 years. PMRs were significantly elevated for cancer of the pancreas and leukemia among those age 20 years and older. Elevated values were also observed for motor vehicle accidents and suicide among nurses in both age groups. Lower than expected mortality from degenerative heart disease and cerebrovascular accidents was seen in working age teachers (age 20-65 years). However, elevated PMRs were detected for carcinoma of the colon, breast, endometrium, brain, and melanoma. Among those 20 years and over, significantly elevated PMRs were also observed for cancers of the ovary and other digestive organs. Elevated PMRs were found for motor vehicle and aircraft accidents. Mortality from cirrhosis of the liver was lower than anticipated in both teachers and nurses. A number of significant PMRs declined when deaths of "homemakers" were withdrawn from the comparison group used to generate PMR values, suggesting that risk of death from various causes among women working outside the home differ from those seen in women who are predominantly in the home.

An allometric study of pulmonary morphometric parameters in birds, with mammalian comparisons

Comprehensive pulmonary morphometric data from 42 species of birds representing ten orders were compared with those of other vertebrates, especially mammals, relating the comparisons to the varying biological needs of these avian taxa. The total lung volume was strongly correlated with body mass. The volume density of the exchange tissue was lowest in the charadriiform and anseriform species and highest in the piciform, cuculiform and passeriform species. The surface area of the blood-gas (tissue) barrier, the volume of the pulmonary capillary blood and the total morphometric pulmonary diffusing capacity were all strongly correlated with body mass. The harmonic mean thickness of both the blood-gas (tissue) barrier and the plasma layer were weakly correlated with body mass. The mass-specific surface area of the blood-gas (tissue) barrier (surface area per gram body mass) and the surface density of the blood-gas (tissue) barrier (i.e. its surface area per unit volume of exchange tissue) were inversely correlated (though weakly) with body mass. The passeriform species exhibited outstanding pulmonary morphometric adaptations leading to a high specific total diffusing capacity per gram body mass, consistent with the comparatively small size and energetic mode of life which typify passeriform birds. The relatively inactive, ground-dwelling domestic fowl (Gallus gallus) had the lowest pulmonary diffusing capacity per gram body mass. The specific total lung volume is about 27% smaller in birds than in mammals but the specific surface area of the blood-gas (tissue) barrier is about 15% greater in birds. The ratio of the surface area of the tissue barrier to the volume of the exchange tissue was also much greater in the birds (170-305%). The harmonic mean thickness of the tissue barrier was 56-67% less in the birds, but that of the plasma layer was about 66% greater in the birds. The pulmonary capillary blood volume was also greater (22%) in the birds. Except for the thickness of the plasma layer, these morphometric parameters all favour the gas exchange capacity of birds. Consequently, the total specific mean morphometric pulmonary diffusing capacity for oxygen was estimated to be about 22% greater in birds than in mammals of similar body mass. This estimate was obtained by employing oxygen permeation constants for mammalian tissue, plasma and erythrocytes, as avian constants were not then available.(ABSTRACT TRUNCATED AT 400 WORDS)

The lung of the emu, Dromaius novaehollandiae: a microscopic and morphometric study

Qualitative and quantitative characteristics suggest that the lung of the emu is poorly adapted for gas exchange when compared with that of other birds. The granular epithelial cells extend over the air capillaries, and the squamous epithelial cells have microvilli indicating a poor differentiation of the epithelium of the exchange tissue. The surface area of the blood-gas tissue barrier per unit body mass was only 5.4 cm2/g, the volume of the pulmonary capillary blood per unit body mass was only 0.93 cm3/kg, and the tissue barrier was unusually thick (0.232 micron). These parameters produce a relatively small total morphometric pulmonary diffusing capacity for oxygen of 0.014 ml O2/sec/mbar/kg. The findings conform to the evolution of a very large flightless bird in a warm environment lacking effective predators.

The structure and innervation of the saccopleural membrane of the domestic fowl, Gallus gallus: an ultrastructural and immunohistochemical study

Microscopic studies have shown the saccopleural membrane in the respiratory system of the domestic fowl to consist of a sheet of three dense layers of collagen fibres covered dorsally and ventrally by mainly simple squamous epithelium. On the ventral surface, which faces into the caudal thoracic air sac, there are occasional ridges of pseudostratified ciliated epithelium. Many nerve bundles are present throughout the membrane, the larger bundles of myelinated and unmyelinated axons being confined to the lamina propria under the dorsal epithelium (parietal pleura). In addition to axonal profiles with the ultrastructural appearance of cholinergic or adrenergic axons, peptidergic-type axons were identified. Immunofluorescence studies demonstrated VIP-, substance P-, somatostatin- and enkephalin-immunoreactive fibres in the membrane. Although it has been suggested that receptors may be present in this region of the respiratory system, none of the axons have features suggestive of sensory terminals, although many axonal profiles are closely associated with the epithelia where no obvious effector cells are present.

Aortico-pulmonary bodies in the domestic fowl: ultrastructure, innervation and secretion

In adult and immature domestic fowl, aggregations of large pale-staining cells were found in the wall of the aorta, and of the pulmonary trunk and arteries, in modified regions typified by interruption or loss of elastic laminae and smooth muscle cells. Encapsulated extramural aggregations of similar cells were identified either on the actual surface or well outside the arterial wall of the aorta, and pulmonary trunk and arteries. The electron microscope revealed that the pale cells in these intramural and extramural structures were granular cells characterised by dense-cored vesicles typically about 60-140 nm in diameter. Supporting cells partly invested the granular cells. These intramural and extramural structures are interpreted as aortico-pulmonary bodies. The extramural and to a lesser extent the intramural cells were associated with many axonal endings and fenestrated blood capillaries. The axonal endings formed presumptive afferent, efferent and reciprocal synapses with the granular cells. Both intra- and extramural granular cells displayed evidence of exocytosis and were also shown by autoradiography to handle amines. It is concluded that the ultrastructural features of these aortico-pulmonary bodies resemble those of the carotid body. It is therefore suggested that the aortico-pulmonary bodies of the domestic fowl have a chemoreceptor function similar to that of the carotid body. It is also suggested that they may have a general secretory function.

The abdominal air sac ostium of the domestic fowl: a sphincter regulated by neuro-epithelial cells?

A microscopic study of the ostium of the abdominal air sac of the domestic fowl has shown that the ostium has a sphincter-like ring of well innervated smooth muscle. Three types of neuro-epithelial cell characterised by their content of numerous large granular vesicles are found in the wall of the ostium. Type I cells are present within the submucosal nerve plexus and appear to be morphologically similar to SIF cells. Type II cells occur in the lamina propria, in clusters or cords, are often associated with fenestrated capillaries, and have synaptic contact with axonal terminals containing small agranular vesicles. The cells of Types I and II are not intra-epithelial and therefore differ from the cells which have been found elsewhere in the respiratory tract of the domestic fowl and other vertebrates. Type III cells are intra-epithelial, and some of those in the basal region of the epithelium are associated with axon terminals. Type III cells are similar in ultrastructure and location to neuro-epithelial cells found elsewhere in the major airways of the domestic fowl. They also resemble cells in neuro-epithelial bodies in amphibian, reptilian and mammalian lungs, although neuro-epithelial bodies have not been found in the lung of this species of bird. The morphology of the ostium suggests that it may have a sphincter-like function, possibly regulated by the neuro-epithelial cells. The presence of a mucociliary epithelium and defensive tissue in the lamina propria indicates that the ostium is the site of defence mechanisms.

Stereological observations on the kidney of the domestic fowl

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Trophic effects of axonal elements upon the type 1 cells of the carotid body of the domestic fowl

The carotid body Type 1 cells of twelve adult domestic fowls were examined with the electron microscope either 5-15 days after distal vagal ganglionectomy (3 birds) or from 5 to 462 days after midcervical vagotomy (9 birds). An increase in the number and size of Type 1 cell granular vesicles was noted after deafferentation by ganglionectomy. In vagotomised birds, degeneration and regeneration of the axonal elements of the carotid body were respectively accompanied by degeneration and then reappearance of the Type 1 cells. It was concluded that axonal elements of the carotid body exert a trophic influence on the Type 1 cells.

Intramural granular cells in the arteries of the carotid body region of the domestic fowl

The major blood vessels of the carotid body region of the domestic fowl were examined with both the light and electron microscope. With the light microscope, argyrophilic cells were found in the wall of the common carotid artery, carotid body artery, oesophagotracheobronchial artery, and the common trunk for the latter two arteries. With the electron microscope, cells containing granular vesicles were found in all the above mentioned arteries. In the wall of the common carotid artery two types of granular cell were found, one with small granular vesicles (60-140 nm) and the other with large granular vesicles (100-300 nm). Capillaries were not present amongst these cells, apposed axonal endings were infrequently seen, and there were no synapses. It is concluded that these cells do not have a chemoreceptor function but may secrete amines or peptides with a local action. Since the cells are located in the baroreceptor zone of the common carotid artery their secretions may modulate baroreceptor activity. In the other three arterial sites and on the distal vagal ganglion there were groups of granular cells characterised by small (60-140 nm) granular vesicles. These granular cells, together with their associated fenestrated capillaries, apposed axonal endings with synapses, and cells resembling carotid body Type II cells were interpreted as aberrant carotid body tissue, presumably with a chemoreceptor function.

Correlations between structure and function in the design of the bat lung: a morphometric study

The lungs of five species of bat Pipistrellus pipistrellus, Miniopterus minor (Peters), Tadarida mops (De Blainville), Cynopterus brachyotis (Muller) and Cheiromeles torquatus (Horstield) have been analysed by morphometric techniques. The mean body weight (W) ranged from 5 g in Pipistrellus pipistrellus to 173 g in Cheiromeles torquatus; the lung volume (VL) ranged from 0.3 cm3 in Pipistrellus to 10 cm3 in Cheiromeles. The volume densities or the main components of the bat lung, namely the parenchyma [VV(p,L)] (the gas exchange region) and the non-parenchyma [VV(np,L)], were closely similar, the VV(p,L) constituting a mean value of 84.2% and the VV(np,L) 15.8% in the five species. The VL, the surface area of the blood--gas (tissue) barrier (St), the pulmonary capillary blood volume (Vc), and the total morphometric pulmonary diffusing capacity (DLO2) were all strongly correlated with body weight. The harmonic mean thickness of the blood--gas (tissue) barrier (tau ht) and the surface density of the blood--gas (tissue) barrier [SV(t,p)] were poorly correlated with W. The bats had a remarkably higher VL than either birds or terrestrial mammals. The Vc in the bat lung was similar to that in the bird lung but higher than that of the terrestrial mammals. The bats had a more extensive St than either the birds or the terrestrial mammals. In the bats the tau ht was thicker than in the birds but thinner than that of the terrestrial mammals. These pulmonary structural adaptations culminated in a higher DLO2 in the bat than either in the birds or in the terrestrial mammals. The superior morphometric properties of the bat lung coupled with the established physiological adaptations may help to explain how the bat lung is capable of providing the immense amount of oxygen demanded by flight.

Ultrastructure of aortic and pulmonary baroreceptors in the domestic fowl

Baroreceptor regions are definitely present in the arterial wall of the aorta and pulmonary arteries of the domestic fowl. In such regions, the arterial wall is modified by the interruption and absence of the elastic laminae and smooth muscle cells. The baroreceptor endings are similar ultrastructurally to the baroreceptors of the mammalian aorta and carotid sinus; therefore they are slowly adapting. Some of the amine- or peptide-containing endings, which are present in the modified regions, share the same Schwann cell with the baroreceptor endings; they probably modulate the stimulus threshold of the baroreceptor endings. Likewise, some of the cholinergic endings share the same Schwann cell with the baroreceptor endings, and may form the efferent branch of a reflex arc and thereby modify the tension of the arterial musculature which is then registered by the baroreceptor endings. There is a possibility that aminergic anc cholinergic endings interact with each other since they sometimes share the same Schwann cell. The encapsulated endings which are reported in this investigation are similar to those of the avian carotid arteries, and they, too, should be slowly adapting to pressure changes in the arterial wall.

Autoradiographic observations on the innervation of the carotid body of the domestic fowl

Tritiated leucine was injected into the distal vagal ganglion of 11 domestic fowl, which survived for 12-24 h under general anaesthesia. The cells of this ganglion are known to be exclusively afferent. EM autoradiography showed that in all 11 birds the vast majority of the silver grains fell upon the nervous tissues of the carotid body. In 5 of these birds a quantitative analysis was made, using point-counting morphometry. The incidence of silver grain per unit area was found to be 26 times greater in axonal endings than in the non-nervous components, and 15 times greater in axons in transit than in non-nervous components. The difference in incidence per unit area between these nervous and non-nervous components was highly significant (P less than 0.001). Of all the observed axonal endings 77% were labelled, but there is evidence that this is a substantial underestimate of the total population of afferent endings; in one bird 88% of the endings were labelled. Of the axons in transit, 18% were labelled. This low value is believed to be related to transfer of the label to the axonal endings by the fast component of axonal transport. Afferent and reciprocal synapses occurred in labelled axonal endings, which were therefore considered to have an afferent function. 'Efferent' type synapses also occurred in labelled endings, and therefore belonged to axons which in fact were afferent in function. It is concluded that the innervation of the carotid body of the domestic fowl is almost entirely afferent, the nerve cell bodies being in the distal vagal ganglion. Only very few efferent axonal endings are present. Ultrastructural features, including synaptic morphology, appear to constitute unreliable criteria for distinguishing between afferent and efferent axonal endings in the carotid body.

Morphometrics of the avian lung. 2. The wild mallard (Anas platyrhynchos) and graylag goose (Anser anser)

The lungs of 5 wild mallard ducks (Anas platyrhynchos) and 5 feral graylag geese (Anser anser) of mean body weight 1.04 and 3.84 kg, respectively, were fixed in situ by intratracheal infusion of 2.3% glutaraldehyde, pH 7.4 and total osmolarity 350 mOsm, at a pressure head of 25 cm, and analysed by standard morphometric techniques. The following data apply to both lungs together, in the fixed state, the first value relating to Anas and the second to Anser in each case: lung volume, 30.4 and 95.3 cm3; volume of exchange tissue, 12.32 and 38.50 cm3; volume of capillary blood, 4.06 and 12.49 cm3; surface area of blood-gas (tissue) barrier per unit body weight, 28.56 and 23.10 cm2/g; surface area of the blood-gas (tissue) barrier per unit volume of lung, 977 and 932 cm2/cm3; surface area of blood-gas (tissue) barrier per unit volume of exchange tissue, 241 and 230 mm2/mm3; harmonic mean thickness of tissue barrier, 0.133 and 0.118 microns; arithmetic mean thickness of tissue barrier, 0.903 and 0.887 microns; harmonic mean thickness of plasma layer, 0.369 and 0.322 microns; mean total morphometric pulmonary diffusing capacity per unit body weight, 3.85 and 3.59 ml O2/min/mm Hg/kg. These morphometric parameters of Anas and Anser are compared with those reported in the literature for the domestic fowl (Gallus gallus), the budgerigar (Melopsittacus undulatus), the house sparrow (Passer domesticus), and the violet-eared hummingbird (Colibri coruscans). The lungs of these six avian species show progressively advancing adaptations, from Gallus, through Anser, Anas, Melopsittacus and Passer, to Colibri, which appear to be consistent with the energetic characteristics of these birds.

A morphometric analysis of the lung of a species of bat

The lungs of five adult Epauleted Fruit-bats (Epomophorus wahlbergi) of mean body weight 96 g were analysed morphometrically. The lung volume per unit body weight was 0.043 cm3/g, the surface area of the tissue barrier (i.e., the effective alveolar surface area) component of the blood-gas pathway per unit body weight was 138 cm2/g, and the surface density of the tissue barrier (surface area of the tissue barrier per unit volume of parenchyma) was 121 mm2/mm3. The harmonic mean thickness of the tissue barrier was between 0.267 and 0.349 micron. The morphometric pulmonary diffusing capacity per unit body weight (DLO2/W) was 0.02 ml O2 per min per mm Hg per g. These values are compared with those of shrews and birds. It is suggested that in bats enlargement of the lungs, small subdivisions of the air spaces, and a thin blood-gas barrier, could be linked with previously reported circulatory adaptations to account for the high oxygen consumption during flight.

An ultrastructural investigation of a baroreceptor zone in the common carotid artery of the domestic fowl

The wall of the common carotid artery of the domestic fowl possesses a baroreceptor zone around the origin of the artery to the carotid body. The zone comprises about 20 small foci which have undergone a fibrous modification. Within these foci there are bare endings, which closely resemble ultrastructurally the baroreceptors of the mammalian carotid sinus in their mitochondrial content, relationship to collagen and elastic fibres, and abnormal organelles. These should be slowly adapting baroreceptors, similar functionally to the baroreceptors of the mammalian carotid sinus. Also present in the baroreceptor zone are a few encapsulated endings, resembling in structure the simplest encapsulated mechanoreceptors of mammals. These, too, should be slowly adapting but may be capable of slightly more subtle responses to pressure changes in the arterial wall. Some presumptive efferent axonal endings are associated with smooth muscle cells, and may modify the tension of the arterial musculature. In general, the afferent innervation of the avian carotid baroreceptor zone appears to be less profuse than that of the mammalian carotid sinus.

Effects of distal vagal ganglionectomy and midcervical vagotomy on the ultrastructure of axonal elements in the carotid body of the domestic fowl

The carotid body of the domestic fowl was examined with the electron microscope after either removal of the distal vagal ganglion or midcervical vagotomy. Almost all the axonal elements of the carotid body degenerated within 5-15 days after ganglionectomy. The degeneration was considered to be due to separation of these axonal elements from their cell bodies (Wallerian degeneration) and indicated that nearly all the nerve supply of the carotid body of Gallus is derived from the vagus nerve. Degeneration of many axonal elements of the carotid body was also seen after midcervical vagotomy, but it took longer (19-41 days) to begin and had greatly increased 207-214 days after operation. It was interpreted as transganglionic degeneration, i.e. severance of the central processes of the distal vagal ganglion cells (by vagotomy) had induced slow degeneration in their peripheral processes (axonal elements in the carotid body). We conclude that the vast majority of the axonal elements in the carotid body of Gallus belong to nerve cell bodies in the distal vagal ganglion and are therefore afferent.

The thickness of avian blood-gas barrier: qualitative and quantitative observations

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Morphometrics of the avian lung. 1. The domestic fowl (Gallus gallus variant domesticus)

The lungs of 5 domestic fowls have been analysed electron microscopically by standard morphometric methods. The anatomical diffusing capacity has been calculated from the relevant parameters. The blood-gas barrier consisted essentially of endothelium, basal lamina, and a very thin squamous epithelial cell. Granular cells are absent and interstitial tissue is minimal. The following measurements are mean values applying to both lungs together, in the fixed state: lung volume, 25.0 cm3; total intrapulmonary blood volume, 6.9 cm3; volume of the exchange tissue, 11.6 cm3; pulmonary capillary blood volume, 3.51 cm3; pulmonary capillary haematocrit, 62.7%; total intrapulmonary air volume, 16.61 cm3; air capillary volume, 6.68 cm3; surface area of the blood-gas barrier, 2.08 m2; surface area of the barrier per unit volume of exchange tissue, 179.5 mm2/mm3; arithmetic mean thickness of the tissue barrier, 1.20 micrometers; harmonic mean thickness of the tissue barrier, 0.314 micrometers; harmonic mean thickness of the plasma layer, 0.342 micrometers. The values of the maximum and minimum morphometric diffusing capacities for the lung (DL02 m) were respectively 3.55 and 1.50 ml O2/min/mm Hg; those for the membrane (Dmo2 m) were 13.61 and 12.01 ml O2/min/mm Hg.

Light microscopic morphometry of the lung of 19 avian species

The lungs of 107 birds of 19 different species from seven orders were fixed in situ. The mean volumes of both fixed lungs together ranged from 0.15 to 95.31 cm3. Histological sections of one lung from each bird were analyzed by point counting with a Zeiss integrating eyepiece to determine the volume densities and thence the absolute volumes of the main functional components of the lung. The mean volume density of the exchange tissue was highest in the 11 passeriform species (53.5%) and lowest in the 2 charadriiform species (34.6%); that for all of the 8 non-passeriform species was 42.6%. The possible significance of these variations in relation to the differing oxygen requirements of these groups of birds is discussed. The parabronchi showed minor variations in the degree of development of the interparabronchial septa, atria, interatrial septa, and atrial muscles. The diameter of the parabronchi (including the mantle of exchange tissue) ranged from about 0.34 mm in the passeriform species to about 0.63 mm in Anser anser; the lumen of the parabronchus accounted for about half of this diameter. Body weight an lung volume were strongly correlated (0.995); the allometric function relating lung volume to body weight was 29.5 w0.988.

The unmyelinated fibre spectrum of the avian cervical vagus nerve

The numbers and diameters of the unmyelinated nerve fibres in the cervical vagus nerve of the domestic fowl were studied electron microscopically. The mean total number was estimated at 7028 in the right nerve and 6774 in the left, the ratio or myelinated to unmyelinated fibres being about 1.3:1. From the numbers of unmyelinated fibres surviving intracranial vagotomy on the right side it was estimated that approximately 5028 (about 72%) were afferent in the right cervical vagus nerve. The diameters of the unmyelinated fibres in the cervical nerve ranged from 0.15 to 2.0 micrometers, about 90% being between 0.45 and 1.04 micrometer. The total number of myelinated and unmyelinated fibres in the cervical vagus nerve of this species of bird appears to be about 16000 on the right side and 15000 on the left.