Crystalline fibril structure of type II collagen in lamprey notochord sheath.

We report here the existence of a crystalline molecular packing of type II collagen in the fibrils of the lamprey notochord sheath. This is the first finding of a crystalline structure in any collagen other than type I. The lamprey notochord sheath has a composition similar to that of cartilage, with type II collagen, a minor collagen component with 1 alpha, 2 alpha and 3 alpha chains, and cartilage-like proteoglycan. The high degree of orientation of fibrils in the notochord makes it possible to use X-ray diffraction to determine collagen fibril organization in this type II-containing tissue. The low angle equatorial scattering shows the fibrils are all about 17 nm in diameter and have an average center-to-center separation of 31 nm. These results are supported by electron microscope observations. A set of broad equatorial diffraction maxima at higher angles represents the sampling of the collagen molecular transform by a limited crystalline lattice, extending over a lateral dimension close to the diameter of one fibril. This indicates that each 17 nm fibril contains a crystalline array of molecules and, although a unit cell is difficult to determine because of the broad overlapping reflections, it is clear that the quasi-hexagonal triclinic unit cell of type I collagen in rat tail tendon is not consistent with the data. The meridional diffraction pattern showed 26 orders with the characteristic 67 nm periodicity found for tendon. However, the intensities of these reflections differ markedly from those found for tendon and cannot be explained by an unmodified gap/overlap model within each 67 nm period. Both X-ray diffraction and electron microscope data indicate a low degree of contrast along the fibril axis and are consistent with a periodic binding of a non-collagenous component in such a way as to obscure the gap region.

A role for glycosaminoglycans in the development of collagen fibrils.

Extensive data on the glycosaminoglycan (GAG) composition and the collagen fibril diameter distribution have been collected for a diverse range of connective tissues. It is shown that tissues with the smallest diameter collagen fibrils (mass-average diameter less than 60 nm) have high concentrations of hyaluronic acid and that tissues with the largest diameter collagen fibrils (mass-average diameter approximately 200 nm) have high concentrations of dermatan sulphate. It is suggested that the lateral growth of fibrils beyond a diameter of about 60 nm is inhibited by the presence of an excess of hyaluronic acid but that this inhibitory effect may be removed by an increasing concentration of chondroitin sulphate and/or dermatan sulphate. It is also postulated that high concentrations of chondroitin sulphate will inhibit fibril growth beyond a mass-average diameter of approximately 150 nm. Such an inhibition may in turn be removed by an increasing concentration of dermatan sulphate such that it becomes the dominant GAG present in the tissue.

Neonatal tetanus in the United States: a sentinel event in the foreign-born.

BACKGROUND: Neonatal tetanus occurred in a 7-day-old infant born to Mexican immigrant parents in Tennessee in February, 1995. This was the first patient with neonatal tetanus reported in the United States since 1989. METHODS: We interviewed the infant's mother and physicians and reviewed the medical record. We conducted a telephone survey of 103 (17%) of the 609 licensed obstetrician/gynecologists practicing in Tennessee to assess vaccination history-taking practices during prenatal care. RESULTS: The mother was a 30-year-old gravida 4 para 3 woman who grew up in rural Mexico. After moving to the United States in 1987, she had delivered two children before this delivery. The hospital-based delivery and nursery stay in February, 1995, were uncomplicated. On the sixth day of life the infant became irritable and developed muscle stiffness. The next day he was examined by a pediatrician who diagnosed neonatal tetanus. The infant recovered fully after a 2-month hospitalization. The survey of obstetrical practices revealed that 61 (59%) of 103 respondents asked about the patient's vaccination status during prenatal care. However, of all respondents, only 14 (14%) confirmed that they specifically asked about prior tetanus vaccinations. Tetanus toxoid was available in 47% of offices on the day of the survey. CONCLUSIONS: Neonatal tetanus can still occur in the United States. This infant's immigrant mother had multiple missed opportunities to be vaccinated against tetanus during her three pregnancies in this country. Health care providers should ask patients about their vaccination status, particularly those patients who are foreign-born or who grew up outside the United States.

Mixed outbreak of parainfluenza type 1 and influenza B associated with tourism and air travel.

BACKGROUND: A preseasonal outbreak of influenza-like illness was reported in a tourist group that had returned from Ireland to the United States on October 1 and 2, 1999. The authors investigated to determine the timing, extent, and nature of the outbreak. METHODS: A cohort study was conducted among the entire group. Cases were defined as illness occurring among tour members who experienced cough or sore throat with onset from September 29 through October 5. Nasopharyngeal and throat cultures were examined for respiratory viruses. RESULTS: Eighteen (60%) of the 30 tourists were ill; the majority (66%) of cases had onset of illness within 1 day of departure from Ireland. Human parainfluenza virus type 1 was isolated from six cultures, and influenza B from three. The attack rate was 100% among the eight persons 65 years of age or older versus 45% among the 22 persons younger than 65 years (P = 0.01). CONCLUSION: International travellers, particularly older persons and members of organized tour groups, may experience increased risks for respiratory viral infection. The recognition and containment of imported infectious diseases depend on prompt reporting and epidemiologic investigation.

67Ga-9N3 uptake by xenografts of human melanotic melanoma in mice.

Tumour uptake of the inert, neutral complex 67Ga-9N3 and the tumour:blood concentration ratio (1,4,7,triazacyclononane-1,4,7, triacetic acid) were measured in mice bearing xenografts of the human melanotic melanoma HX118. Between 1 and 4 h after the injection the tumour:blood ratio increased from 3.5 to 21 and the concentration of 67Ga-9N3 in the tumour decreased from 0.43 to 0.13% g-1. During the first 24 h the concentration of 67Ga-9N3 in the tumour exceeded that in all other tissues except the liver and kidneys. The tumour:blood ratio and tissue distribution of 67Ga-9N3 at 4 h were compared with those of four other complexes. The results indicated that of the five complexes 67Ga-9N3 would be the most suitable for tumour imaging at early times after administration. Imaging would not be restricted to gamma emitting 67Ga as there is also the possibility of using the 9N3 ligand to bind 111In for single photon emission computed tomography (SPECT), 68Ga for positron emission tomography (PET) or even stable Ga for direct in vivo nuclear magnetic resonance (NMR) detection.

Obstetric consultations during labor and delivery in a university-based family practice.

This study retrospectively examined the use of obstetrical consultants by family medicine residents and faculty at the University of Washington Hospital from July 1, 1980, to June 30, 1981. Of 125 deliveries, 104 (83 percent) were vaginal deliveries, 99 percent of which were performed by the family physician involved. There were 21 (17 percent) cesarean sections. Before the audit began, 13 complications of labor and delivery were established as criteria suggesting the need for consultation. Medical records were retrospectively examined for complications meeting these criteria. Formal consultations occurred in 32 percent of all deliveries. Of the patients with at least one of the 13 complications, 75 percent had consultations obtained. Patients with these complications had intrapartum risk scores that were significantly higher than patients without the listed complications. Apgar scores at 1 and 5 minutes were significantly lower in the group of patients meeting the consultation criteria (7.0 vs 8.0 at 1 minute; 8.3 vs 9.0 at 5 minutes). The criteria successfully identified a group of high-risk patients and could be an appropriate guide for decision making in the specific setting studied. Patients without one of the predetermined complications had a low rate of surgical intervention (cesarean section or midforceps deliveries); the negative predictive value was 98 percent.

Estimating the undetected burden of influenza hospitalizations in children.

During the 2004-2005 influenza season two independent influenza surveillance systems operated simultaneously in three United States counties. The New Vaccine Surveillance Network (NVSN) prospectively enrolled children hospitalized for respiratory symptoms/fever and tested them using culture and RT-PCR. The Emerging Infections Program (EIP) and a similar clinical-laboratory surveillance system identified hospitalized children who had positive influenza tests obtained as part of their usual medical care. Using data from these systems, we applied capture-recapture analyses to estimate the burden of influenza related-hospitalizations in children aged<5 years. During the 2004-2005 influenza season the influenza-related hospitalization rate estimated by capture-recapture analysis was 8.6/10,000 children aged<5 years. When compared to this estimate, the sensitivity of the prospective surveillance system was 69% and the sensitivity of the clinical-laboratory based system was 39%. In the face of limited resources and an increasing need for influenza surveillance, capture-recapture analysis provides better estimates than either system alone.

Candidemia in pediatric outpatients receiving home total parenteral nutrition.

This is a cohort study of pediatric outpatients receiving total parenteral nutrition (TPN) and follow-up care in a Tennessee hospital between January and June 1999. The study was conducted following an increase in the incidence of candidemia. Of 13 children receiving home TPN, five had candidemia; three were due to Candida parapsilosis. Case patients were more likely to have an underlying hematologic disease (P = 0.02) as well as previous history of fungemia (P = 0.02). Two case patients had successive candidemia episodes 3 months apart; karyotypes and RAPD profiles of each patient's successive C. parapsilosis isolates were similar. Candida spp. were frequently detected in hand cultures from cohort members (four of 10) and family member caregivers (nine of 11); C parapsilosis was isolated from five caregivers. Our findings underscore the challenges of maintaining stringent infection control practices in the home health care setting and suggest the need for more intensive follow-up and coordination of home TPN therapy among pediatric patients.

Electron microscope evidence for an 80 A unit in collagen fibrils.

Connective tissues are composite structures containing collagen, elastin, glycosaminoglycans, minerals, water and other minor components. In all cases the collagen exists predominantly in fibrillar form. The size distribution of the fibrils does, however, vary markedly with both age and the mechanical requirements of the tissue. Little is known about the mechanism of fibril formation in vivo, although some information is now available form in vitro polymerisation studies. We have now collected new and extensive electron microscope data on the size of collagen fibrils from tendon, skin, cornea and other tissues from both fetal and immature animals. The results reported here show that the diameters of the collagen fibrils thus measured lie close to a multiple of 80 A, a result which may be simply and readily interpreted in terms of the collagen microfibril and its mode of packing.

Growth and development of collagen fibrils in immature tissues from rat and sheep.

The collagen fibril diameter distribution of four immature tissues from both rat and sheep have been determined from the transverse sections observed in the transmission electron microscope. In many instances before birth, the form of the distribution for the tissues is both unimodal and sharp and the mean diameters of the distributions lie close to a multiple of 80 A. For some tissues, the collagen fibril diameter distributions may be resolved into a number of components, each of which represents a population of fibrils with a diameter close to a multiple of 80 A (8 nm). These data confirm and extend previous observations by the authors that small collagen fibrils growth occurs by the accretion of 80 A units. The form of the collagen fibrils diameter distribution at birth is broad for the sheep tissues but narrow for the rat tissues, thus confirming that the range of fibril diameters at this stage of life reflects the differing degree of development of precocious and altricious animals.

Plants under Climatic Stress: II. Low Temperature, High Light Effects on Chloroplast Ultrastructure.

Mesophyll chloroplasts of the C(4)-pathway grasses Sorghum and Paspalum and of the C(3)-pathway legume soybean undergo ultrastructural changes under moderate light intensities (170 w.m(-2), 400-700 nanometers) at a tme when photosynthesis is much reduced by low temperature (10 C). The pattern of ultrastructural change was similar in these species, despite some differences in the initial sites of low temperature action on photosynthesis and differences in their mechanisms of CO(2) fixation. Starch grains in the chloroplasts rapidly reduce in size when chilling stress is applied. At or before the time starch grains completely disappear the membranes of the individual stromal thylakoids close together, reducing the intraspace between them while the chloroplast as a whole begins to swell. Extensive granal stacking appears to hold the thylakoids in position for some time, causing initial swelling to occur in the zone of the peripheral reticulum, when present. At more advanced stages of swelling the thylakoid system unravels while the thylakoid intraspaces dilate markedly. Initial thylakoid intraspace contraction is tentatively ascribed to an increase in the transmembrane hydrogen ion gradient causing movement of cations and undissociated organic acids from the thylakoid intraspace to the stroma. Chloroplast swelling may be caused by a hold-up of some osmotically active photosynthetic product in the chloroplast stroma. After granal unraveling and redilation of the thylakoid intraspaces, chloroplasts appear similar to those isolated in low salt hypotonic media. At the initial stages of stress-induced ultrastructural change, a marked gradient in degree of chloroplast swelling is seen within and between cells, being most pronounced near the surface of the leaf directly exposed to light.

Ultrastructural organization of skin: classification on the basis of mechanical role.

In our previous developmental study on skin we reported that correlations existed between the collagen fibril diameter distribution, glycosaminoglycan content and composition, and mechanical role. In this work we present new but related electron microscope data on the ultrastructure of skins from flounder, marlin, cod, frog, toad, caiman, viper, pigeon, whale and opossum. It is shown that mammalian and avian body skins generally contain relatively sharp unimodal distributions of fibril diameter consistent with a "passive" mechanical role. In contrast most reptilian and fish skins have broad, right-skewed (or bimodal) distributions of fibril diameters compatible with the exotendinous attributes required of an "active" skin. A study of the changing form of the collagen fibril diameter distribution with depth in the dermis is also reported.

Preservation of corneal collagen fibril structure using low-temperature procedures for electron microscopy.

Low-temperature dehydration and embedding techniques have been used to preserve the transverse structure of corneal collagen fibrils for study using electron microscopy. The diameters of the fibrils, which were found to be about 45% larger than those determined previously for specimens prepared for electron microscopy using conventional dehydration and embedding, lie close to those deduced from low-angle X-ray diffraction patterns from untreated hydrated specimens of cornea.

An estimate of the mean length of collagen fibrils in rat tail-tendon as a function of age.

A theoretical expression has been derived for the mean collagen fibril length in tendon based on the assumption that collagen fibrils originate in cell surface invaginations and terminate either at some remote cell surface or another collagen fibril bundle. The expression thus determined requires knowledge of the effective lengths of the fibrocytes (or fibrocyte assemblies) and the cellular content of the tendon. Both of these parameters have been measured experimentally as a function of age for rat-tail tendon using a combined light microscope and electron microscope approach. The results obtained for immature tendon suggest that the mean collagen fibril length is at least equal to the critical length required to maintain the appropriate tensile properties. In the most mature tissue studied, however, the mean-collagen fibril length is in excess of 100 times the critical length.

Ovine ceroid-lipofuscinosis II: Pathologic changes interpreted in light of biochemical observations.

Ceroid-lipofuscinosis is studied in a breed of sheep and the histochemical and ultrastructural changes are interpreted in light of the known chemical composition of cytosomes. It is concluded that the ovine disease is a lysosomal proteinosis. It is postulated that the multilamellar arrays reflect a complex three-dimensional structure of alternating lipid and protein with the proteinaceous component being specific polypeptides. This is supported by powder X-ray diffractions at 10A implying a repeating proteinaceous unit in the structures. The coherent size of diffracting units was remarkably similar to the periodicity of lamellae observed in electron micrographs of lipopigment cytosomes. The fluorescent and staining characteristics of lipopigment can be explained by the above conclusion and postulate.

Hospital responses to a data-driven statewide quality improvement project.

BACKGROUND: The overall success of any continuous quality improvement (CQI) project lies in the ability to measure changes resulting from the project and to show that changes have resulted n improved care. METHOD: A software tool was developed to categorize hospital responses and activities implemented by hospitals as a result of the Cooperative Cardiovascular Project CCP). Information was captured regarding the hospital's acceptance of data and the educational/interventional strategies implemented. Hospital size, number of acute myocardial infarction patients treated, indicator performances, and type of presentation given (on-site versus regional visit) was entered to allow analysis of factors affecting the response. RESULT: sixty-one of 107 hospitals responded to the peer review organization. Of those, 49% planned further educational activities and 75% planned to implement some form of CQI activity. Comparison of responses in relation to the type of presentation received suggested that on-site presentations are associated with higher response rates and more intense quality improvement efforts. This also could be attributed to other factors such as hospital size, teaching environment, or number of acute myocardial infarction patients treated. CONCLUSION: The system developed allowed us to collate hospital improvement efforts as a result of CCP. The system is limited in its ability to identify those activities taking place before CCP. Further development and refinement of the tool is warranted to document quality improvement efforts and determine best strategies for peer review organization intervention.