New geochronological, paleoclimatological, and archaeological data from the Narmada Valley hominin locality, central India.

The oldest known fossil hominin in southern Asia was recovered from Hathnora in the Narmada Basin, central India in the early 1980's. Its age and taxonomic affinities, however, have remained uncertain. Current estimates place its maximum age at >236ka, but not likely older than the early middle Pleistocene. The calvaria, however, could be considerably younger. We report recent fieldwork at Hathnora and associated Quaternary type-sections that has provided new geological and archaeological insights. The portion of the exposed 'Boulder Conglomerate' within the Surajkund Formation, which forms a relict terrace and has yielded the hominin fossils, contains reworked and stylistically mixed lithic artifacts and temporally mixed fauna. Three mammalian teeth stratigraphically associated with the hominin calvaria were dated by standard electron spin resonance (ESR). Assuming an early uranium uptake (EU) model for the teeth, two samples collected from the reworked surface deposit averaged 49+/-1ka (83+/-2ka, assuming linear uptake [LU]; 196+/-7ka assuming recent uptake [RU]). Another sample recovered from freshly exposed, crossbedded gravels averaged 93+/-5ka (EU), 162+/-8ka (LU) or 407+/-21ka (RU). While linear uptake models usually provide the most accurate ages for this environment and time range, the EU ages represent the minimum possible age for fossils in the deposit. Regardless, the fossils are clearly reworked and temporally mixed. Therefore, the current data constrains the minimum possible age for the calvaria to 49+/-1ka, although it could have been reworked and deposited into the Hathnora deposit any time after 160ka (given the LU uptake ages) or earlier (given the RU ages). At Hathnora, carbonaceous clay, bivalve shells, and a bovid tooth recovered from layers belonging to the overlying Baneta Formation have yielded (14)C ages of 35.66+/-2.54cal ky BP, 24.28+/-0.39cal ky BP, and 13.15+/-0.34ky BP, respectively. Additional surveys yielded numerous lithics and fossils on the surface and within the stratigraphic sequence. At the foot of the Vindhyan Hills 2km from the river, we recovered a typologically Early Acheulean assemblage comprised of asymmetrical bifaces, large cleavers with minimal working, trihedral picks, and flake tools in fresh condition. These tools may be the oldest Acheulean in the Narmada Valley. Several lithics recovered from the Dhansi Formation may represent the first unequivocal evidence for an early Pleistocene hominin presence in India. In situ invertebrate and vertebrate fossils, pollen, and spores indicate a warm, humid climate during the late middle Pleistocene. High uranium concentrations in the mammalian teeth indicate exposure to saline water, suggesting highly evaporative conditions in the past. Late Pleistocene sediment dated between 24.28+/-0.39cal ky BP and 13.15+/-340ky BP has yielded pollen and spores indicating cool, dry climatic conditions corresponding to Oxygen Isotope Stage 2 (OIS 2). An early Holocene palynological assemblage from the type locality at Baneta shows evidence for relatively dry conditions and a deciduous forest within the region. The Dhansi Formation provisionally replaces the Pilikarar Formation as the oldest Quaternary formation within the central Narmada Basin. The Baneta Formation, previously dated at 70ka to 128ka, correlates with the late Pleistocene and early Holocene. Our results highlight the need for further Quaternary geological and paleoanthropological research within the Narmada Basin, especially because dam construction threatens these deposits.

ESR dating at Mezmaiskaya Cave, Russia.

Mezmaiskaya Cave has yielded more than 10,000 artifacts, thousands of very well preserved faunal remains, and hominin remains, found in seven Middle Paleolithic (Mousterian) and three Upper Paleolithic levels. A complete Neanderthal infant skeleton was preserved in anatomical juxtaposition lying on a large limestone block, overlain by the earliest Mousterian layer, Layer 3. Twenty-four skull fragments from a 1-2 year-old Neanderthal infant, showing post-mortem deformation, occurred in a pit originating in the Mousterian Layer 2 and penetrating into underlying layers 2A and 2B(1). Bone from Layer 2A was dated by AMS 14C at 35.8-36.3+/-0.5 kyr BP. Direct dating of Neanderthal bone from Layer 3 gave an age of 29 kyr, but that is now considered to be due to contamination by modern carbon. Fourteen large mammal teeth from Layers 2 through 3 have been dated by standard electron spin resonance (ESR). Low U concentrations in both the enamel and dentine ensure that ESR ages do not depend significantly on the U uptake model, but do depend strongly on the sedimentary dose rates. Assuming a sedimentary water concentration equal to 20 wt%, ESR ages for the Mousterian layers range from 36.2 to 73.0+/-5.0 ka.

ESR dating: is it still an 'experimental' technique?

Nearly 25 years ago, Motoji Ikeya demonstrated the potential of ESR dating. From a single substance (stalagmitic carbonate) and a single site (Akiyoshi Cavern), the field has grown to include materials from all over the world and time periods from a few thousand years ago to several million years ago. A vigorous program of instrumentation development has increased the precision of measurements as well as opening up new ways of collecting and interpreting spectra. Yet there are still references to ESR dating as an 'experimental' technique, one which cannot be trusted to produce dates that are accurate or precise. This paper discusses areas for which this is true and suggests what should be done to convince skeptics. Other areas for which the evidence suggests that ESR is at least as reliable as 'standard' methods will also be covered.

Improvements in dating tooth enamel by ESR.

ESR dating requires that growth curves be determined by interpreting complex spectra. Spectra, however, can vary significantly in shape and field position between different samples, or occasionally between subsamples, even though the mineralogy remains the same. In some cases, this spectral variability does not affect the resulting accumulated dose calculation. In other cases, signal subtraction may be needed. However, some samples that until recently might have been considered unsuitable for dating are now shown to yield accurate and precise results because a broad interference peak is integral to the hydroxyapatite signal. By studying the spectrum at the Q-band frequency, it can be shown that the interfering signal in most cases is not a problem for dating. A second concern has been that artificially irradiating sample aliquots can introduce a short-lived component that is simply an unstable enhancement of the dating signal. The apparent accumulated dose from growth curves created immediately after irradiation is considerably greater than that after annealing, although the curve's shape remains unchanged. Annealing both the natural and artificially irradiated signal shows the dating signal's lifetime to be greater than 10(10) years.

Electron microscopy study of explanted intraocular lenses from clinically noninfected eyes.

PURPOSE: To determine whether intraocular lenses (IOLs) in clinically noninfected eyes are coated with a significant, bacteria-containing biofilm. SETTING: The Oxford Eye Hospital, Oxford, United Kingdom. METHODS: Twenty-six IOLs, removed for reasons other than endophthalmitis from 26 patients attending the Oxford Eye Hospital over a 3 year period, were examined by electron microscopy. Immediately following explantation, the IOL was placed in glutaraldehyde 4% in 0.1 M phosphate buffer solution and processed for scanning electron microscopy (SEM). Areas of interest were reprocessed for transmission electron microscopy (TEM). RESULTS: There was no evidence of a bacterial biofilm on any IOL. In 5 IOLs, significant host cellular debris was seen at the tip of the haptic or at the optic-haptic junction. In 4 of them, clusters of coccoid-shaped structures were seen at the optic-haptic junction on SEM, but examination by TEM showed these structures to be melanosomes, not bacteria. CONCLUSION: We found no evidence to suggest that a significant number of IOLs are coated with a bacterial biofilm in clinically noninfected cases. We advocate the use of TEM to distinguish between coccoid bacteria and melanosomes.

Electron microscopy findings on an intraocular lens in the uveitis, glaucoma, hyphaema syndrome.

PURPOSE: To report the electron microscopic findings on an explanted intraocular lens in a patient with the uveitis, glaucoma, hyphaema syndrome. METHODS: Scanning and transmission electron microscopy were undertaken on a coccoon of cellular material from the tip of the intraocular lens haptic. RESULTS: Scanning electron micrographs showed densely packed coccoid-like structures on the haptic surface. By transmission electron microscopy these structures proved to be melanosomes. CONCLUSIONS: The scanning electron micrographs described in this report are similar to those reported in patients with chronic post-operative uveitis, but to our knowledge have not been shown before in association with the uveitis, glaucoma, hyphaema syndrome. Transmission electron microscopy determined that the coccoid-like structures were melanosomes. The melanosomes are probably derived from damaged pigment epithelial cells or iris stromal melanocytes secondary to recurrent chafing of the haptic against the posterior surface of the iris.

Subclavian vein anatomic subtypes defined by digital cinefluroscopic venography prior to permanent pacemaker lead insertion.

Digital cinefluoroscopic venography of the subclavian vein was performed in 26 consecutive patients. The optimal stored image of the anticipated venipuncture site was magnified, road mapped, and used to compare with fluoroscopic-guided venipuncture. Two anatomic subtypes for both subclavian veins were observed. For the left subclavian vein, a gradual curve was seen most often (57%), while the remainder (43%) exhibited an "s"-shaped curve. For the right subclavian, a gradual curve was observed most frequently (60%) while an acute 90 degrees angle was noted in the remainder (40%). The "s"-shaped curve in the left subclavian vein necessitated redirection of the needle site both laterally and cranially. In three or 12% of patients venography showed either subclavian thrombosis or a persistent left superior vena cava and lead insertion was moved to the opposite side. Successful venipuncture and subsequent cannulation of the subclavian vein was achieved with the first or second passage of the needle in 22 or 85% of the 26 patients. Digital cinefluoroscopic venography appears to be both safe and rapid and may facilitate insertion of permanent pacemaker leads into the subclavian vein.

Interaction of L. pneumophilia and a free living amoeba (Acanthamoeba palestinensis).

Co-cultivation of Legionella pneumophila serogroup I and Acanthamoeba palestinensis in Neff's medium at 35 degrees C resulted in the intracellular multiplication of the bacteria as demonstrated by electron microscopy and immunofluorescence. In the closed experimental system used, the number of legionellae rose from 10(7) colony forming units (c.f.u.)/ml initially to a maximum of 10(10) c.f.u./ml on day 5. Legionellae were seen in expelled phagosomes, in some amoebae filling the cytoplasm and in others in which the process of encystment appeared to have commenced. At 20 degrees C the acanthamoebae phagocytosed and digested the legionellae. The bacteria disappeared from the co-cultivation flask by day 2 but reappeared in low numbers (10(2) c.f.u./ml) by day 6 suggesting that even at this temperature some intra-amoebal multiplication occurred.

The demonstration, by immunofluorescence, of Legionella pneumophila organisms in human lung tissue embedded in epoxy resin.

Legionella pneumophila serogroup 1 has been demonstrated by indirect immunofluorescence in human lung tissue fixed in 10% formal saline and embedded in epoxy resin. The organism was visualised using Rabbit serogroup 1 antibody and Sheep anti rabbit fluorescein conjugate. The fluorescent labelled organism was found distributed throughout the tissue with focal areas in alveolar spaces and also visualised by electron microscopy in the same tissue. This method therefore enables specific identification of the L. pneumophila organism with the antiserum and also affords the opportunity of studying the bacterium ultrastructurally in the same tissue.