Regrowth Patterns Research Articles

Regrowth patterns of plantar callus

A-scan ultrasound was used to measure the thickness of plantar callus, from scalpel debridement to regrowth. Twenty-six calluses (4 female and 7 male subjects) were studied over a nine-week period; 6 of these calluses (3 subjects) were followed over a further nine-week period. Three main patterns were identified, producing either a fast, medium or slow regrowth over the first couple of weeks. These patterns were reproduced for five of the six calluses studied over the second period of regrowth. The patterns of regrowth were not related to surface area or thickness of the callus. However, trends were identified with site. Some 66.7% of calluses occurring over the 2nd metatarsal head had slow patterns of regrowth and 71% of those over the 5th metatarsal head exhibited fast regrowth patterns. Although further work needs to be undertaken to identify other factors which may influence the patterns, these findings have important clinical implications when considering the treatment of plantar calluses, for example the timing of treatment intervention, the appropriateness of pressure relieving padding and even the amount of callus debridement itself.

Embryonic central nervous system transplants mediate adult dorsal root regeneration into host spinal cord.

The aim of this study was to determine whether embryonic central nervous system transplants assisted cut dorsal root axons of adult rats to regenerate into the spinal cord. Rats received transplants of embryonic spinal cord, hippocampus, or neocortex into dorsal quadrant cavities aspirated in the lumbar enlargement. The transected L5 dorsal root stump was secured between the transplant and the spinal cord. Regenerated dorsal roots were subsequently labeled by using immunohistochemical methods to detect calcitonin gene-related peptide. Calcitonin gene-related peptide-immunoreactive axons extended into all host spinal cords examined, but the patterns of regrowth differed in rats that had received embryonic spinal cord and brain transplants. In rats with embryonic spinal cord transplants, regenerated axons traversed the dorsal root/spinal cord interface, entered the spinal cord, and frequently formed plexuses with arborizations in motoneuron pools; some of these axons established synapses on spinal cord neurons. In rats with embryonic brain transplants, regenerated axons were diffusely distributed in the spinal cord but did not form plexuses. Few axons regenerated into the spinal cords of lesion-only animals. The results of quantitative analyses confirmed these findings. These findings suggest that transplants of embryonic spinal cord and brain supply cues that enable cut dorsal roots to regenerate into the host spinal cord and that the cues provided by spinal cord transplants favor more extensive growth than do those provided by brain transplants. These cues are likely to depend in part on neurotrophic effects of embryonic central nervous system tissues. Therefore, embryonic central nervous system transplants, especially spinal cord grafts, may contribute to techniques for restoring interrupted spinal reflex arcs.

3D-recurrence-patterns of gliobastomas after CT-planned postoperative irradiation

Background and purpose: The introduction of computed-tomography as an advanced planning tool for the irradiation of intracranial tumours led to a controversial discussions about the optimal target-volume for the primary and postoperative treatment of malignant gliomas. This study analyses the three-dimensional tumour regrowth pattern relative to the treated volume which included the macroscopic preoperative tumour and 2-cm safety margin. Materials and methods: Seventy-nine patients with histologically-confirmed Glioblastoma multiforma and documented recurrence who were irradiated in our department between 1990 and 1996 were reviewed. With the help of a computer program written for this purpose, the PTV of the CT-based treatment plan was reconstructed and its spatial outline compared with the reconstructed volume of the recurrent tumour in the control CT-study. Results: In 33 out 34 patients for which the CT-study showing tumour-recurrence was available the recurrence was completely situated within the original 90%-isodose. Only one tumour surpassed the outside surface of the PTV but was predominantly situated within the original tumourbed and suggests a tumour-regrowth within the high dose volume. Conclusions: The above results show that target-volumes based on the preoperative size of the enhanced tumour mass well cover the site of recurrence in nearly all cases. The findings suggest dose escalation to a more restricted volume.

Effect of brain edema on the recurrence pattern of malignant gliomas

To assess the influence of initial preoperative brain edema in malignant gliomas on regrowth patterns. 79 patients with histologically verified supratentorial malignant glioma were prospectively studied by magnetic resonance imaging (MRI) before and every 2-3 months after surgery. The median follow-up time was 11 months. We correlated the configuration of the initial vasogenic edema on T2-weighted images with tumor regrowth patterns on contrast-enhanced T1-weighted images. 35/47 tumor regrowths (75%) imitated the initial edema configuration, while 11/47 occurred within the initial tumor bed; in one case tumor recurrence was multilocal. In glioblastoma, tumor regrowth patterns correlate positively with the configuration of the initial vasogenic brain edema. The initial, "presurgical" peritumoral edema should thus be considered when planning further treatment.

Biotic Interactivity between Grazers and Plants: Relationships Contributing to Atmospheric Boundary Layer Dynamics

Abstract During 1987 and 1988 First ISLSCP (International Satellite Land Surface Climatology Project) Field Experiment (FIFE) studies conducted in the tallgrass prairie of central Kansas, variations in ungulate grazing intensity produced a patchy spatial and temporal distribution of remaining vegetation. Equally variable plant regrowth patterns contributed further to a broad array of total primary production that resulted in a pronounced mosaic of grazing impacts. This regrowth potential, derived from a relative growth rate (RGR) equation comparing ungrazed and grazed plants, determines much of the ecosystem dynamics within and among the grazed pastures and between years. Rates of change in new plant growth (ΔRGRg) ranged from −100% to +40%; however, 78% of the time in 1987 and 71% in 1988, productivity increased as a function of grazing intensity. Since plant growth potential in ungrazed (RGRug) and grazed systems (RGRg) have inherently different attributes, interactions with the abiotic environment may ...

Patterns of aquatic weed regrowth following mechanical harvesting in New Zealand hydro-lakes

Patterns of aquatic weed regrowth following mechanical harvesting in New Zealand hydro-lakes

Yield and Quality of WW-Iron Master and Caucasian Bluestem Regrowth

Old World bluestems (Bothriochloa spp.) have been seeded on over a million hectares of marginal farmland in Oklahoma and Texas, yet we know little about their regrowth yield and quality. The objective was to determine seasonal pattern of forage regrowth yield and quality of leaves and stems of WW-Iron Master (B. ischaemum [L.] Keng) and Caucasian (B. caucasica [Trin.] C.E. Hubb.) bluestem when 4-week regrowth was harvested at weekly intervals from early May through mid-September. Four plots of each bluestem were established in each of the 4 blocks (32 plots total). Harvesting was rotated so that 4-week regrowth of each bluestem was harvested weekly from 1 of the 4 plots in each block during 1988 and 1989 to determine regrowth yield, in vitro dry matter digestibility (IVDMD), and crude protein (CP) of leaves and stems. Forage regrowth of both species peaked in June both years. Regrowth during August averaged 10 and 35% of June regrowth in 1988 and 1989. WW-Iron Master produced 80 and 45 % greater 4-week regrowth than Caucasian in 1988 and 1989. WW-Iron Master produced 75 and 28% greater leaf regrowth than Caucasian in 1988 and 1989 and twice as many stems both years. Leaf and stem IVDMD of WW-Iron Master averaged 2 to 6 percentage units higher than Caucasian. Leaf CP of WW-Iron Master averaged 2 percentage units higher than Caucasian during May and June. However, stem CP of WW-Iron Master averaged 1 percentage unit lower than Caucasian. Grazing management plans need to consider that the majority of bluestem forage production was restricted to a 1 month period in June. This technique of sampling 4-week regrowth every week during the growing season was an effective method for determining the seasonal regrowth pattern.

The effect of past grazing intensity on the vigour ofThemeda triandraandTristachya leucothrix

Abstract Tuft vigour of important sourveld grasses was indexed by measuring the regrowth, during a full season's rest, of tufts of Themeda triandra Forssk. and Tristachya leucothrix Nees, which (1) had not been grazed, (2) had been leniently, or (3) had been severely grazed during the previous two growing seasons. A sequential harvesting technique was applied and regrowth was expressed in terms of above‐ground herbage‐mass accumulation and etiolated growth. Patterns of regrowth were similar for both species. Severe grazing during the previous two years significantly reduced topgrowth yields during the first 27 to 31 weeks of rest compared to tufts which had previously been leniently or not grazed. Etiolated growth was greater on leniently and ungrazed tufts than on severely grazed tufts for 13 to 15 weeks after the commencement of spring growth, whereafter there were no significant differences. The regrowth patterns of tufts for all intensities of defoliation suggests that the vigour of severely grazed tu...

Cyclic Winter Grazing Patterns in Brent Geese and the Regrowth of Salt- Marsh Grass

This paper describes the large-scale spatial and temporal patterns of grazing on salt-marsh by Dark-Bellied Brent Geese Branta bernicla bernicla in winter and examines them in relation to grazing optimization theory. The numbers and spatial distribution of geese feeding on salt-marsh were recorded, on average, every 2.5 days from October to April 1991/92, and the data analysed for regular cyclic patterns of grazing within areas of the marsh. The mean percentage ground cover of the main food plant, Puccinellia maritima (Poaceae), was estimated in all areas and the proportion of each area composed of short vegetation was measured. The effects of grazing on the age structure of leaves of P. maritima, and on the patterns of regrowth following grazing, were monitored in swards of high, medium and low mean P. maritima cover. Eleven of 23 defined areas of salt-marsh were grazed by geese infrequently (fewer than five records) or never. These areas were clearly distinguished from those used frequently for at least part of the winter by their lower coverage of short vegetation (average 9%, compared with 40% for frequently used areas). Of the 12 frequently grazed areas, six showed evidence of cyclic patterns of grazing, with the interval between grazing bouts ranging from 7 to 15 days. The remaining six areas showed only weak evidence or no evidence of cyclic grazing patterns. The available evidence suggested that disturbance, position in relation to roost and inland feeding areas, and the occurrence of night-time feeding may influence whether or not grazing cycles occur. The time required for the complete regrowth of grazed leaf tissue was greater than 50 days but on cyclically grazed areas, regrazing intervals were much shorter than this. The geese were therefore grazing partially depleted swards. The lengths of cycles were unrelated to the intensity of grazing (measured in goose min m -2 ) but positively related to the percentage cover of P. maritima in the sward. Grazing resulted in a younger leaf age structure on tillers of P. maritima, particularly in swards of low cover. Because geese showed no selection for younger leaves or unbitten tillers, it is suggested that the shorter cycle lengths on lower biomass swards represent a preference for the higher nutrient quality provided by the younger leaf age structure following grazing.

Dynamics and Pattern of a Managed Coniferous Forest Landscape in Oregon

We examined the process of fragmentation in a managed forest landscape by comparing rates and patterns of disturbance (primarily clear—cutting) and regrowth between 1972 and 1988 using Landsat imagery. A 2589—km2 managed forest landscape in western Oregon was classified into two forest types, closed—canopy conifer forest (CF) (typically, > 60% conifer cover) and other forest and nonforest types (OT) (typically, < 40 yr old or deciduous forest) The percentage of CF declined from 71 to 58% between 1972 and 1988. Declines were greatest on private land, least in wilderness, and intermediate in public nonwilderness. High elevations (> 914 m) maintained a greater percentage of CF than lower elevations (< 914 m). The percentage of the area at the edge of the two cover types increased on all ownerships and in both elevational zones, whereas the amount of interior habitat (defined as CF at least 100 m from OT) decreased on all ownerships and elevational zones. By 1988 public lands contained °45% interior habitat while private lands had 12% interior habitat. Mean interior patch area declined from 160 to 62 ha. The annual rate of disturbance (primarily clear—cutting) for the entire area including the wilderness was 1.19%, which corresponds to a cutting rotation of 84 yr. The forest landscape was not in a steady state or regulated condition which is not projected to occur for at least 40 yr under current forest plans. Variability in cutting rates within ownerships was higher on private land than on nonreserve public land. However, despite the use of dispersed cutting patterns on public land, spatial patterns of cutting and remnant forest patches were nonuniform across the entire public ownership. Large remaining patches (< 5000 ha) of contiguous interior forest were restricted to public lands designated for uses other than timber production such as wilderness areas and research natural areas.

Growth responses of arctic graminoids following grazing by captive lesser snow geese.

The effects of grazing by captive goslings of the Lesser Snow Goose on coastal vegetation at La Pérouse By. Manitoba were investigated. Swards of Carex subspathacea, Festuca rubra and Calamagrostis deschampsioides were grazed once for different periods (0-180 min) and regrowth of vegetation determined, based on measurements of standing crop, net above-ground primary production (NAPP) and forage quality (leaf nitrogen content). The amounts of foliage removed from swards of Carex subspathacea increased with the length of the grazing period, but after 44 days of regrowth there were no significant differences in above-ground biomass between control and grazed plots. While the amount of foliage removed by goslings from swards of Festuca rubra increased with the length of the grazing period (except after 150 min of grazing), the increase in biomass following defoliation was similar among treatments. Goslings removed little biomass from swards of Calamagrostis deschampsioides, even when the opportunity for grazing was 180 min. No significant differences in standing-crop or NAPP between grazed and ungrazed plots were detected by the end of summer. Grazing had no significant effect on amounts of nitrogen in leaf tissue of all species, suggesting that faecal nitrogen was not rapidly incorporated into plant biomass within the growing season. Patterns of regrowth of these species are compared to that of Puccinellia phryganodes. An increase in goose numbers in recent years has led to birds foraging on less preferred species, such as Calamagrostis deschampsiodes and Festuca rubra. Their poor nutritional quality and a lack of a rapid growth response following defoliation may explain, in part, the decline in the weight of wild goslings recorded over the last decade.

Kill kinetics and regrowth patterns of Escherichia coli exposed to gentamicin concentration-time profiles simulating in vivo bolus and infusion dosing.

The relative influence of peak concentration (Cmax) versus the area under the antibiotic concentration-time curve (AUC) on the bactericidal effect of gentamicin against Escherichia coli NCTC 10418 was studied. Bacteria in the lag phase were exposed to an in vitro gentamicin concentration series which mirrored the concentrations determined in patients after 80-mg intravenous bolus (1 min) and 80-mg intravenous infusion (30 min) doses. Bacterial viable cell counts and gentamicin concentrations were measured before and during antibiotic exposure. Both the Cmax and AUC were shown to be factors determining antibacterial activity; however, the Cmax was an independent determinant of effect. These findings indicate that bolus intravenous dosing with gentamicin could maximize bactericidal activity. Increased efficacy could result at any given daily antibiotic dose if delivered via bolus with long intervals (12 to 24 h) between doses if appropriate precautions to avoid toxicity are taken.

Overcompensation by plants: Herbivore optimization or red herring?

The increased growth rates, higher total biomass, and increased seed production occasionally found in grazed or clipped plants are more accurately interpreted as the results of growth at one end of a spectrum of normal plant regrowth patterns, rather than as overcompensation, herbivore-stimulated growth, plantherbivore mutualisms, or herbivore enhanced fitness. Plants experience injury from a wide variety of sources besides herbivory, including fire, wind, freezing, heat, and trampling; rapid regrowth may have been selected for by any one of the many types of physical disturbance or extreme conditions that damage plant tissues, or by a combination of all of them. Rapid plant regrowth is more likely to have evolved as a strategy to reduce the negative impacts of all types of damage than as a strategy to increase fitness following herbivory above ungrazed levels. There is no evolutionary justification and little evidence to support the idea that plant-herbivore mutualisms are likely to evolve. Neither life history theory nor recent theoretical models provide plausible explanations for the benefits of herbivory.

Meningiomas of the lateral skull base: Neurotologic manifestations and patterns of recurrence

The eradication of basicranial meningiomas by traditional surgical techniques is often hindered by neoplastic entanglement with critical neurovascular structures. Apparent, complete tumor resection is frequently followed by extensive, yet clinically silent, recurrent disease with local infiltration of bone, cranial nerves, and brain. Fifty-five cases of sphenoid wing or parasellar meningioma were analyzed to identify clinical manifestations suggestive of early tumor recurrence. Regrowth patterns were then defined according to preoperative radiographic and intraoperative surgical findings. Medial tumor regrowth, involving the cavernous sinus, caused neurapraxia of cranial nerves III, IV, or VI, with associated diplopia or ophthalmoplegia. Inferior (caudal) regrowth of disease involved the infratemporal fossa, pterygomaxillary space, or paranasal sinuses by bony erosion of the middle cranial fossa floor or through natural anatomic foramina and fissures. Such inferior extension was manifested clinically by facial hypesthesia, trismus, and referred otalgia caused by trigeminal nerve involvement and by autophony or serous otitis media related to eustachian tube obstruction. Posterior tumor regrowth occurred along the petrous bone and horizontal carotid canal, resulting in internal auditory meatus erosion and cerebellopontine angle extension with associated tinnitus, hearing loss, unsteadiness, and occasional facial twitching. While the clinical and radiographic evaluations of any patient with a suspected recurrent basicranial meningioma are critical in planning the method and magnitude of reoperation, an understanding of potential recurrence patterns can be used in devising more extensive, combined approaches that may allow complete tumor extirpation at the initial surgical intervention.

Apical control of lateral bud development and shoot growth in mulberry (Morus alba)

Measurements of changes in the degree of dominance by upper laterals over lower ones in coppice shoots (1‐year‐old stems) of 12‐year old low‐ pruned stumps of mulberry (Morus alba L. cv. Shin‐ichinose) were made by removal of upper stem sections (pruning) or of lateral buds (debudding.) before spring bud burst, as part of a study of the factors involved in dominance relationships between the developing buds and elongating shoots. Besides inhibition of lower laterals by the upper, leading shoots, there was evidence for mutual inhibition (competition) of neighboring laterals along the stem. Thus in stems in which every other bud, or 4 out of every 5 buds were removed, there was a delay in growth cessation of lower laterals and their greater elongation than in controls. Such competition was seen to exist even between the uppermost and sub‐terminal laterals, since the former elongated more in the absence of the latter.In contrast to high and middle pruned stems, the delay in sprouting of the buds in low‐pruned stems resulted in limited elongation of the shoots from such buds. This inhibition was removed when all the stems on a stump were pruned to the same length, suggesting that it was associated with intact stems with actively growing laterals. Patterns of regrowth of the short shoots (lower laterals) after summer pruning (middle‐pruned) depended on the extent of removal of other stems with vigorously growing, upper laterals. These results demonstrate that both acropetal and basipetal influences are important in bud and shoot dominance relationships.

Microbiological and Trihalomethane Responses to Booster Chlorination

ABSTRACTTwo zones of a water distribution supply area receiving treated surface water were used to study the effect of booster chlorination on bacterial regrowth. In the first year of the study general patterns of bacterial regrowth were observed, and in the second year one of the areas was booster chlorinated at the outlet from a surface reservoir. In both years of the study the heterotrophic plate counts showed a seasonal pattern. In the second year there was a large increase in plate counts from mid‐July to October in both of the study areas. During this period, booster chlorination was unable to prevent bacterial regrowth. The addition of chlorine to produce an initial free chlorine residual of 0.5 mg/1 resulted in a reduction in bacterial numbers, but with further retention in the distribution system bacterial regrowth occurred. There was little increase in the trihalomethane (THM) concentration following booster chlorination, but booster chlorination appeared to increase the assimilable organic carbon concentration.

If Rabbits Can Regenerate the Eye's Lens, Will Science Find a Way for Humans to Do It?

THE ABILITY of rabbits to regenerate the lens of the eye was observed and described by French investigators in 1824. Now, Arlene Gwon, MD, Department of Ophthalmology, University of California, Irvine, and colleagues have used that model in developing techniques to induce lens regeneration. The investigators use ultrasound to break up the material within the rabbit lens capsule (phacoemulsification). The cȯntents are aspirated, and fetal cells are placed within the lens capsule. Regrowth Pattern The pattern of regrowth follows that of embryonic development. The crystallin proteins that develop are the same as in the adult lens, but in proportions similar to those found in fetal lenses, the researchers explained at the recent Research to Prevent Blindness science writers' conference in Arlington, Va. They add that this model can be used to study the influence of growth factors, either to promote or inhibit growth. Presently, 1 million Americans have cataract surgery

Regrowth patterns of glioblastoma multiforme related to planning of interstitial brachytherapy radiation fields

Regrowth patterns of glioblastoma multiforme related to planning of interstitial brachytherapy radiation fields

Regrowth patterns of glioblastoma multiforme related to planning of interstitial brachytherapy radiation fields.

Recognition of the local nature of glioblastoma has generated an increasing interest in treatment using radioactive implants (interstitial brachytherapy). A key issue in such implantation is the configuration of the radiation field in relation to the resected tumor. In particular, should radiation be provided to the area from which the tumor has been resected? To clarify this issue, we evaluated patterns of tumor regrowth into this resected area in 62 patients. Three patterns of computed tomographic scan-documented tumor regrowth were recognized: preferential (regrowth to refill the resected area only), circumferential (regrowth into the resected area and previously uninvolved contiguous brain) and away (local regrowth into noncontiguous brain, sparing the surgical bed). Regrowth of the tumor 6.3 to 6.8 months after resection was seen in 59 of 62 patients (95.2%). Preferential regrowth was seen in 32 of 62 patients (51.6%), and circumferential regrowth was seen in 27 of 62 patients (43.5%). Regrowth away was seen in 3 of 62 patients (4.8%). Radiation fields planned for interstitial brachytherapy must adequately include the resected area because of the high incidence of tumor regrowth into that area.

Effects of protein kinase C activators on mouse skin in vivo.

Tumor-promoting phorbol ester, 12-O-tetradecanoylphorbol-13-acetate (TPA) is known to have many biological effects on epidermal cells [14]. TPA activates protein kinase C directly both in vivo and in vitro [3], and protein kinase C is the receptor of TPA [5, 8]. Therefore, it is possible that biological effects of TPA on epidermis are mediated by protein kinase C, which is also known to be activated by diacylglycerol generated from phosphoinositides of cell membrane [9]. It has been reported that synthetic diacylglycerol, 1-oleoyl-2-acetylglycerol (OAG), as well as TPA, is able to penetrate cell membrane and activate protein kinase C in intact cells [1, 4, 9]. OAG has some biological effects on epidermal cells as does TPA [7, 12]. We investigated marcoand microscopic changes that could be induced by topical application of OAG, as compared with application of TPA. Dorsal skin (6 cm z) of Balb/c and Swiss-Webster mice aged 10 weeks were shaved with an electric shaver so as to avoid injury. TPA (20 gg) and OAG (40 rag) were each dissolved in 100 ~tl acetone. Each 100-1~1 acetone solution was applied with a microsyringe onto the shaved back skin of the mice. In consideration of previous reports [7, 11] these concentrations of TPA and OAG could be thought to be effective biologically on epidermal cells; 100 lal of acetone only was used as control. Five mice were used per group. The mice were treated with each solution once weekly for 3 weeks. They were killed 1 week after the last treatment, and the skins were taken and stained with HE. The hair regrowth patterns in each group of Balb/c mice are shown in Fig. 1 a c . Hair regrowth