Visual evoked potentials in phenylketonuria: association with brain MRI, dietary state, and IQ

At separate institutions, pattern reversal visual evoked potentials (VEPs) were recorded in children and older patients with phenylketonuria and compared with MRI of the brain. In nine patients aged less than 14 years, who were still on a diet low in phenylalanine, VEPs were clearly abnormal in only one and the abnormalities seen on MRI were mild. In 27 patients aged 14-31 years VEPs were abnormal in more than 80%, with significant reduction of amplitude and prolongation of latency despite the general absence of visual symptoms and abnormalities on routine neuro-ophthalmological examination. Among the older patients there was no significant correlation between VEP measures and plasma phenylalanine or tyrosine concentrations; neither was the incidence of VEP abnormalities dependent on whether or not the patients were still on a low phenylalanine diet. Some VEP amplitude measures were inversely correlated with the MRI lesion score, perhaps reflecting the severity of white matter abnormalities in the parieto-occipital region. In the older patients the amplitude of VEPs to stimulation of the central 8 degrees of the visual field was significantly correlated with IQ. The study confirms the high incidence of subclinical visual pathway involvement in older children and adults with phenylketonuria, and suggests the possibility of a link between the abnormal appearance of subcortical white matter on MRI and a physiological index of function of the CNS. As there was no evidence of general intellectual decline, it is suggested that the correlation between central field VEP amplitude and IQ may reflect abnormal development during infancy. Abnormalities on MRI, on the other hand, seem to be more closely related to current dietary state and phenylalanine concentration.

An update and lessons from whole-genome sequencing projects

A number of prokaryotic and eukaryotic genomes are currently being sequenced. Already, the nucleotide sequences of four yeast chromosomes and of 2.2 Mb from Caenorhabditis elegans have been reported. Human genomic sequences have also been used in comparative studies with both mouse and Fugu rubripes.

The rate of osteoclastic destruction of calcified tissues is inversely proportional to mineral density

This study examined the relative ease with which three dissimilar mineralized tissues from one individual organ were resorbed by osteoclasts in vitro. Cells released from the long bones of prehatch chicks by agitating fragments of the chopped bones in medium were cultured for 24 hours on slices cut from an Elephas maximus molar so that enamel, dentine, and coronal cementum were present in bands on the surface of the slice. The resultant pits were measured using a video-rate, line-confocal reflection light microscope system. Variations in tissue mineralization were characterized by analysis of digital backscattered electron images. The enamel pits were smaller than the dentine and the cementum pits, but the dentine and cementum pits were not significantly different from each other. The sizes of the pits correlated with the relative mineral densities of the three tissues, showing that the rate of osteoclastic destruction of calcified tissues is inversely proportional to mineral density. This indicates that the initial step in osteoclasis, the removal of the mineral phase, determines the volume removed and is the rate-limiting step.

Mineral density quantitation of the human cortical iliac crest by backscattered electron image analysis: variations with age, sex, and degree of osteoarthritis

Bone samples from the rim of the iliac crest were obtained at autopsy from 59 patients aged 23 to 75 years, of whom 10 men and 10 women aged 50-75 years had osteoarthritis diagnosed by hand X-rays. An equal number in the same age group and 10 men and 9 women aged less than 50 years were without osteoarthritis. After embedding the bone in PMMA, the blocks were cut, polished, and coated with carbon. The fractions of bone falling within four consecutive bands of signal level were derived from digital backscattered electron imaging. Normal males had more low and medium density bone and normal females more very high density phase tissue proportionately. In both male and female osteoarthritis cases, low and medium fractions were low. The very high density fraction was mainly calcified fibrocartilage; when it was excluded from the calculations, the low, medium, and high phases occurred equally in normal males but increased stepwise in normal females and in osteoarthritis cases of both sexes. The results suggest a lower rate of bone renewal in females than males, and in male osteoarthritis subjects than normal males. An increased proportion of bone of high density would reduce the quality of the bone by increasing its stiffness.

Volumes of chick and rat osteoclasts cultured on glass

We have examined the relationship between the number of nuclei of an osteoclast and its volume. Chick and rat cells were released from long bones by chopping the shafts and flushing the fragments in Eagle's Minimum Essential Medium with added 10% fetal calf serum. The bone cell suspension was seeded onto glass coverslips. In Experiment 1, rat and chick cells were allowed to settle for 15 minutes, more medium was then added, and the cells were cultured in 5% CO2 at 37 degrees C for 4 hours. In Experiment 2, only rat cells were used, and the cells were cultured in the presence or absence of 10(-6) M 3-amino-1-hydroxypropylidene-1,1-bisphosphonate (APD) in the medium for 4 or 6 hours. The coverslips were washed in 37 degrees C phosphate-buffered saline and fixed for 24 hours in 2.5% glutaraldehyde in isotonic cacodylate buffer (initially 37 degrees C). The chick cells were critical point dried (CPD) or freeze dried (FD); all rat cells were FD. After drying, cells were coated with gold by vacuum evaporation. The volumes and areas of osteoclasts were measured using a video-rate, line-confocal reflection laser scanning microscope and the number of nuclei in each cell was counted. The volumes and volumes per nucleus of the FD cells were larger than those of the CPD cells but there was no significant difference in plan-areas. Rat osteoclasts were larger than chick cells in all the measured parameters except the mean number of nuclei/cell. The correlation coefficients for the areas, volumes, and the numbers of nuclei for rat and chick cells were all high (r > 0.725). The volumes and volumes per nucleus, but not the areas or areas per nucleus, of the osteoclasts cultured with APD were significantly smaller than control cells. We conclude that FD causes less shrinkage than CPD; chick osteoclasts are about two-thirds the size of rat osteoclasts; and 10(-6) M APD caused a reduction of rat osteoclast volume and volume per nucleus of 21%.

Vital confocal microscopy in bone

We wished to exploit confocal microscopy for high spatial and temporal resolution vital microscopy in bone. To this end, we evolved implants with glass windows supported in titanium, which were placed in the medial proximal tibial plateau of the rabbit, and special small, self-focussing objectives (dry 10/0.25, water immersion 20/0.45, and oil immersion 45/0.65 and 120/1.0) which mated and matched to the conical window entrance section of the metal components. At intervals of up to 21 months after implant healing, these lenses were used to study live tissue using two genera of confocal microscope: multiple aperture disc, tandem scanning, microscopes for observation in reflection, and video rate confocal laser scanning microscopes for recording, mainly in the fluorescence mode. The latter allowed the study of a variety of intravenously administered substances, including fluorescein, fluorescein-dextrans, fluorescent microspheres, acridine orange, DASPMI, calcein, and tetracycline. We were able to remove blood, stain cells with fluorescent markers, and replace them into the circulation. Calcein and tetracycline bind to the mineral front in bone: this labelling was studied in progress. We observed that both substances partition and remain for long periods (at least days) in adipocytes. Further characterisation of the system used both confocal fluorescence and scanning electron microscopy methods in the study of retrieved implants. These studies showed that the subimplant cortical bone remodelled to a less compact structure with a rich microvasculature extremely close to bone. The points of attachment of bone to glass were found to involve coarse fibres, with the matrix containing large numbers of large cells: some of this tissue was cartilage and some immature bone. An amorphous, mineralised matrix was in immediate contact with glass. The results provide further confirmation of the general utility of high-scan speed confocal methodology in physiology.

Bactericidal/permeability-increasing protein (BPI) is an important antigen for anti-neutrophil cytoplasmic autoantibodies (ANCA) in vasculitis

Indirect immunofluorescence (IIF) techniques have shown that ANCA are useful serological markers for some small vessel vasculitides, and ELISA assays, using purified molecules as solid-phase ligand, have helped to identify proteinase 3 (PR3) and myeloperoxidase (MPO) as two of the major ANCA antigens. There remain a substantial number of serum samples, which are positive by IIF, yet recognize neither PR3 nor MPO (double-negative samples). We found, by Western blot analysis of soluble neutrophil granule proteins, that certain of these double-negative samples recognized a 55-kD doublet of which the first eight residues shared N-terminal amino acid sequence homology with BPI, a potent antibiotic towards Gram-negative bacteria. We developed a simple, quick and robust two-step immunobiochemical method to purify BPI. This was then employed to detect anti-BPI autoantibodies by ELISA and Western blot analysis. We tested 100 double-negative samples and 400 consecutive new samples sent for routine ANCA testing in the anti-BPI ELISA. We found that 45 of the 100 double-negative and 44 of the 400 new routine samples recognized BPI. By Western blot analysis 20/20 positive anti-BPI samples blotted the 55-kD protein. Inhibition assays confirmed the specificity of binding. Review of the 89 anti-BPI-positive patients showed a male dominance (M:F ratio 55:34), a mean age of 60.4 years and clinical diagnoses ranging from organ limited vasculitis to widespread systemic vasculitis.

Effects of ethanol on bone cells in vitro resulting in increased resorption

Abuse of alcohol has been found to be an important risk factor for fractures and osteoporosis, and tissue culture experiments have indicated that low concentrations of ethanol can affect bone formation and resorption. This study investigated direct effects of ethanol on bone cells using an in vitro resorption assay. Osteoclasts from long bones of 19-day prehatch chicks were seeded onto slices of dentine and cultured with control medium alone, or medium containing 0.001%, 0.01% or 0.1% ethanol, at 37 degrees C with 5% CO2 for 24 h before being removed. The volumes and areas of resorption pits made in the dentine were measured using confocal laser reflection microscopy (Lasertech 1LM21 system) and the pits counted. An increase in the pit numbers and mean pit areas, volumes and volume/area ratios was observed with 0.001% and 0.01% ethanol, with a dose-related, bell-shaped curve of resorption. Greatest mean volume resorbed per pit (p < 0.05), mean area resorbed per pit (p < 0.01) and number of pits was at 0.01% ethanol. Volume/area (mean depth) per pit was greatest at 0.001% ethanol (p < 0.05). This study has shown that ethanol, even at blood concentrations experienced by the social drinker, has an immediate direct effect on bone cells in vitro, resulting in increased resorption by osteoclasts.

Erectile dysfunction in multiple sclerosis. Associated neurological and neurophysiological deficits, and treatment of the condition

Forty-eight men with multiple sclerosis and erectile dysfunction were evaluated. Emphasis was placed on the neurological features and the relationship between impotence and the bladder dysfunction in multiple sclerosis. Erectile failure was invariably associated with pyramidal signs in the lower limbs and with urinary symptoms. All of the men with impotence and marked pyramidal dysfunction in their legs were found by cystometric studies to have bladder hyperreflexia. The severity of the urinary symptoms was related to the degree of pyramidal impairment in the lower limbs. The posterior tibial and the pudendal cortical evoked potentials were abnormal in most of the men with multiple sclerosis and erectile failure. However, recording the pudendal cortical responses in patients with multiple sclerosis and impotence provided no more information than the tibial cortical evoked potentials. The neurological examination findings together with the results of the neurophysiological and cystometric tests suggest that erectile dysfunction in multiple sclerosis is due to spinal lesions situated proximal to the sacral cord. The feasability of papaverine intracorporeal injection therapy for men with multiple sclerosis and impotence was assessed. Papaverine intracorporeal injections produced satisfactory erections in the majority of the impotent men. Erectile failure in patients with multiple sclerosis was successfully managed for up to 2 years, by intracorporeal self-injection therapy.

Effects of age on the ability to remember common and rare proper names

Difficulties in remembering proper nouns increase with age. One factor is that names are arbitrary labels. Another is that because many people share the same names, mutual discriminability between names is less than than that between other words. Discriminability between names may reduce as the number of acquaintances increases. Also, most people have both a first and a second name. These have to be learned as a pair, but they may be of unequal distinctiveness and so be unequally well remembered. An experiment was designed to evaluate the relative effects of distinctiveness of first and second names on free and cued recall. Subjects (aged 60-69 or 70-79 years, matched on Mill-Hill vocabulary score) were asked to remember one of four lists of 16 names. Each was presented four times. The names were either common, rare, or a combination of the two--a common first name with a rare surname, or vice versa. Subjects first freely recalled the names. They were next cued by either first name or surname to recall the remaining half of name pairs. Interactions between effects on recall of subjects' ages and of the relative distinctiveness of first and second names provide partial support for a model incorporating "relative distinctiveness" as a factor in failures of name recall in old age.

Simulation of bone resorption-repair coupling in vitro

In the normal adult human skeleton, new bone formation by osteoblasts restores the contours of bone surfaces following osteoclastic bone resorption, but the evidence for resorption-repair coupling remains circumstantial. To investigate whether sites of prior resorption, more than the surrounding unresorbed surface, attract osteoblasts or stimulate them to proliferate or make new matrix, we developed a simple in vitro system in which resorption-repair coupling occurs. Resorption pits were produced in mammalian dentine or bone slabs by culturing chick bone-derived cells on them for 2-3 days. The chick cells were swept off and the substrata reseeded with rat calvarial osteoblastic cells, which make bone nodules in vitro, for periods of up to 8 weeks. Cell positions and new bone formation were investigated by ordinary light microscopy, fluorescence and reflection confocal laser microscopy, and SEM, in stained and unstained samples. There was no evidence that the osteoblasts were especially attracted to, or influenced by, the sites of resorption in dentine or bone before cell confluence was reached. Bone formation was identified by light microscopy by the accumulation of matrix, staining with alizarin and calcein and by von Kossa's method, and confirmed by scanning electron microscopy (SEM) by using backscattered electron (BSE) and transmitted electron imaging of unembedded samples and BSE imaging of micro-milled embedded material. These new bone patches were located initially in the resorption pits. The model in vitro system may throw new light on the factors that control resorption-repair coupling in the mineralised tissues in vivo.

High temporal and spatial resolution studies of bone cells using real-time confocal reflection microscopy

Chick and rat bone-derived cells were mounted in sealed coverslip-covered chambers; individual osteoclasts (but also osteoblasts) were selected and studied at 37 degrees C using three different types of high-speed scanning confocal microscopes: (1) A Noran Tandem Scanning Microscope (TSM) was used with a low light level, cooled CCD camera for image transfer to a Noran TN8502 frame store-based image analysing computer to make time lapse movie sequences using 0.1 s exposure periods, thus losing some of the advantage of the high frame rate of the TSM. Rapid focus adjustment using computer controlled piezo drivers permitted two or more focus planes to be imaged sequentially: thus (with additional light-source shuttering) the reflection confocal image could be alternated with the phase contrast image at a different focus. Individual cells were followed for up to 5 days, suggesting no significant irradiation problem. (2) Exceptional temporal and spatial resolution is available in video rate laser confocal scanning microscopes (VRCSLMs). We used the Noran Odyssey unitary beam VRCSLM with an argon ion laser at 488 nm and acousto-optic deflection (AOD) on the line axis: this instrument is truly and adjustably confocal in the reflection mode. (3) We also used the Lasertec 1LM11 line scan instrument, with an He-Ne laser at 633 nm, and AOD for the frame scan. We discuss the technical problems and merits of the different approaches. The VRCSLMs documented rapid, real-time oscillatory motion: all the methods used show rapid net movement of organelles within bone cells. The interference reflection mode gives particularly strong contrasts in confocal instruments. Phase contrast and other interference methods used in the microscopy of living cells can be used simultaneously in the TSM.

Inhibition of bone resorption by selective inactivators of cysteine proteinases

Inactivators of cysteine proteinases (CPs) were tested as inhibitors of bone resorption in vitro and in vivo. The following four CP inactivators were tested: Ep475, a compound with low membrane permeability which inhibits cathepsins B, L, S, H, and calpain; Ep453, the membrane-permeant prodrug of Ep475; CA074, a compound with low membrane permeability which selectively inactivates cathepsin B; and CA074Me, the membrane-permeant prodrug of CA074. The test systems consisted of 1) monitoring the release of radioisotope from prelabelled mouse calvarial explants and 2) assessing the extent of bone resorption in an isolated osteoclast assay using confocal laser microscopy. Ep453, Ep475, and CA074Me inhibited both stimulated and basal bone resorption in vitro while CA074 was without effect; the inhibition was reversible and dose dependent. None of the inhibitors affected protein synthesis, DNA synthesis, the PTH-enhanced secretion of beta-glucuronidase, and N-acetyl-beta-glucosaminidase, or the spontaneous release of lactate dehydrogenase. Ep453, Ep475, and CA074Me dose-dependently inhibited the resorptive activity of isolated rat osteoclasts cultured on bone slices with a maximal effect at 50 microM. The number of resorption pits and their mean volume was reduced, whilst the mean surface area remained unaffected. Again, CA074 was without effect. Ep453, Ep475, and CA074Me, but not CA074, when administered subcutaneously at a dose of 60 micrograms/g body weight inhibited bone resorption in vivo as measured by an in vivo/in vitro assay, by about 20%. This study demonstrates that cathepsins B, L, and/or S are involved in bone resorption in vitro and in vivo. Whilst cathepsin L and/or S act extracellularly, and possibly intracellularly, cathepsin B mediates its effects intracellularly perhaps through the activation of other proteinases involved in subosteoclastic collagen degradation.

Autoantibodies to lactoferrin and histone in systemic vasculitis identified by anti-myeloperoxidase solid phase assays

We aimed at confirming the antigen specificity recognized by anti-neutrophil cytoplasm antibodies (ANCA) in patients presenting systemic vasculitis with anti-myeloperoxidase (MPO) activity on ELISA. Thirty-five consecutive patients with reactivity in anti-MPO ELISA and systemic microscopic vasculitides were tested in slot and Western blot analyses. Eleven of 35 sera exhibited binding in Western blot studies with the MPO preparation used in the ELISA: five sera bound at the size of MPO, but five sera reacted with a 78 kD species (p78) co-purifying with MPO, and one serum blotted both MPO and p78. Sequence analysis and antigen-specific assays including Western blot studies showed that p78 is lactoferrin. All anti-lactoferrin positive sera, but no anti-MPO positive sera, also exhibited anti-nuclear binding on HEp2 cells with specificity for histone. We concluded that: (a) a subgroup of patients presenting systemic vasculitis with false anti-MPO reactivity on ELISA had anti-lactoferrin antibodies; (b) anti-lactoferrin was associated with anti-nuclear activity with specificity for histone; (c) these patients had systemic vasculitis without histological evidence of immune complex deposition.

Questions of quality and quantity--a morphological view of bone biology

The quality of bone may be as important as its quantity, influencing bone strength and turnover. Using quantitative BSE (backscattered electron) imaging, we have found changes in the mineral density of bone with age, the proportion of denser bone increasing, and discontinuities occurring in the mineral phase between packets of bone. SEM of resorptive fields showed that severing of trabeculae occurs with deep, vertical excavations; their thinning is by long, narrow, resorption grooves extending from node to node. Grooved regions may become deeper, undercut and burrowing. In vitro, we showed that larger osteoclasts made larger pits. However, the volume of tissue resorbed per nucleus did not increase, and could decrease. Interactions between osteoclasts and autologous osteoblastic cells were observed by time-lapse video microscopy in vitro. Message-mediated contact behaviour, dependent upon the state of activation of both cell types, resulted in changes in the territory of the responding cell. The numbers and sizes of gap junctions between rat parietal bone cells in situ were investigated using confocal fluorescence and reflection microscopy and polyclonal antisera to connexin-43 peptides. The junctions reached approximately 1.3 microns in diameter, with 0.2 microns as the limit of detection. The extent of connectivity and communication may also affect bone quality.

Deciduous enamel defects in low-birth-weight children: correlated X-ray microtomographic and backscattered electron imaging study of hypoplasia and hypomineralization

Enamel does not remodel, and disturbances occurring during development may remain in the tooth as a permanent record of the upset. Mineralization in prenatal and postnatal deciduous enamel was studied in the shed deciduous incisors of low-birth-weight (LBW: < 2kg) children. The specific objective was to gain further insight into the mechanism of formation of developmental defects of enamel. Sections at a resolution of 22-40 microns were reconstructed using X-ray microtomography (microCT) giving absolute measurements of linear absorption coefficient for AgK alpha radiation. Detail to ca. 1 micron resolution was obtained using automated, digital backscattered electron (BSE) imaging of PMMA-embedded material. Matching the histograms of BSE and microCT images made possible the calibration of the mean atomic number-dependent signal in the BSE images. The comparison of abnormal, affected enamel regions and post-recovery, normal, unaffected regions could be made in the same teeth, since these zones were easily recognized from the distribution of hypoplasia and hypomineralization. The microCT values, converted to calculated mineral densities, ranged from 2.3 g cm-3 to 2.6 g cm-3 in LBW hypoplastic, and between 2.65 and 2.78 g cm-3 in control primary enamel and post-defect, post-natal LBW enamel. Hypoplasia with or without minimal hypomineralization indicated recovery of the ameloblasts in the maturation phase. Disturbance during late matrix formation and early maturation resulted in hypoplasia and hypomineralization.

Pathway specificity of noradrenergic plasticity in the dentate gyrus

Previous experiments have described highly specific effects of noradrenergic agonists on synaptic transmission in the dentate gyrus (DG). For example, perfusion of hippocampal slices with the beta-noradrenergic agonist isoproterenol induces a long-lasting potentiation (LLP) of extracellularly recorded responses following stimulation of the medial perforant path (PP), and long-lasting depression (LLD) of responses evoked by stimulation of the lateral PP (Dahl D, Sarvey JM, 1989, Proc Natl Acad Sci USA 86:4776-4780). To examine the possible interactions of LLP, LLD, and long-term potentiation induced by tetanic stimulation (LTP), the authors recorded extracellular field potentials evoked in the DG by stimulation of the lateral or medial perforant path following LTP and LLP or LLD, invoked in different orders. After establishment of LLP or LLD by bath application of isoproterenol, subsequent tetanization of the respective afferents resulted in additional potentiation of the medial PP-evoked response and return of the lateral PP-evoked response to baseline levels. In other slices, application of isoproterenol after establishment of LTP resulted in further potentiation of medial PP-evoked responses but no change in the potentiated response evoked by lateral PP stimulation. Thus the pathway specificity was maintained irrespective of the history of previous potentiation or depression. Experiments using the specific beta 1 antagonist metoprolol further confirmed pathway specificity. Perfusion with 20 microM of metoprolol appeared to reduce LTP evoked by stimulation of the medial but not lateral PP. In a subsequent experiment, metoprolol in the absence of tetanization produced LLD of the medial PP-evoked response and LLP of the lateral PP-evoked response, opposite to the effects of ISO.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of medium acidification by alteration of carbon dioxide or bicarbonate concentrations on the resorptive activity of rat osteoclasts

Little is known about the extracellular conditions or factors that stimulate mature osteoclasts to resorb mineralized tissues. Isolated mammalian osteoclasts are strongly stimulated by protons in HEPES-buffered culture media in the absence of CO2 and HCO3-, but it has been reported that cell-mediated Ca2+ release from bone organ cultures is increased only when media are acidified by reduction of HCO3- concentrations, and not by increasing PCO2 (considered models of metabolic and respiratory acidosis, respectively). We investigated this question using disaggregated rat osteoclasts cultured on dentin slices for 24 h. The number of pits resorbed per osteoclast was stimulated in media acidified by manipulation of either HCO3- or CO2 concentrations. In experiments in which incubator CO2 was varied, resorption was almost abolished in the presence of 2.5% CO2 at pH 7.61 but increased in a stepwise manner up to 1.3 pits per osteoclast when dentin slices were cultured with 10% CO2 at pH 6.97. The depths and widths of pits, measured using a confocal laser reflection microscope, also tended to increase with increasing CO2 and decreasing pH. However, in experiments where pH was lowered by reducing medium HCO3-, pit size decreased, partially offsetting the increased number of pits resorbed per osteoclast. These findings suggest that rat osteoclasts may be more sensitive to stimulation by CO2 acidosis than by HCO3- acidosis, at least in the short term, and may possibly reflect local regulatory processes in bone.

Three-dimensional photographic study of cancellous bone in human fourth lumbar vertebral bodies

In an analysis of the 3D architecture of cancellous bone, two-dimensional techniques are of limited value. A simple technique employing stereophotographs of whole sections of lumbar vertebrate made possible a detailed description of the 3D structure of the normal fourth lumbar vertebral body and its changes with ageing and osteoporosis. Parallax measurements were used to calculate the real lengths of horizontal trabeculae. The bone presented a continuous spectrum of microstructure, from a honeycomb of tubes, to plates and braces and, finally, fragile rods. A distinct pattern was produced in osteoporotic samples by the removal of horizontal and selected vertical trabeculae followed by a thickening of the remaining vertical trabeculae in the peripheral regions. Very long, thin horizontal trabeculae were formed in all three zones (superior, middle and inferior) during this process. The observation of porotic architecture in intact specimens points to the inadequacy of the clinical criterion of the occurrence of a fracture in judging the osteoporotic state.

The effect of 3-amino-1-hydroxypropylidene-1,1-bisphosphonate (ADP) on the resorptive function of osteoclasts of known nuclear number

Bisphosphonates (BP) are known to suppress osteoclastic resorption in vivo and in vitro, but doubt persists as to how, and the effect of BP on the resorptive capability of osteoclasts of known nuclear number is unknown. We aimed to find whether the addition of 3-amino-1-hydroxypropylidene-1,1- bisphosphonate (APD) changed the nuclear profile of an osteoclast population in vitro, and to measure the resorptive efficiency of individually characterized osteoclasts in the presence and absence of the BP. Prehatch chick bone cells were cultured for 24 hours on slices of dentine in medium with or without added APD at 10(-6) M or 10(-8) M, or in control medium on dentine presoaked with 10(-6) M APD for 48 hours. Total pit counts, and pit depths, areas and volumes for pits made by osteoclasts of known nuclear number, were found using confocal video-rate laser reflection microscopy and 3-D image analysis software. APD in the medium inhibited resorption and reduced the volume, area, and depth resorbed per nucleus per chick osteoclast. The nuclear number distribution did not shift significantly, suggesting that no preferential effect arose from the APD affecting one size of cell more than another. The large reduction found in pit numbers, depths, areas, and volumes in the APD dentine-pretreated group supports previous views that BP released during resorption act as metabolic inhibitors, altering protein synthesis by the cell. Larger cells made larger pits, but resorptive efficiency was similar for different cell sizes within the control or APD-treated groups.(ABSTRACT TRUNCATED AT 250 WORDS)