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Biomedical subjects

Y A Mostafa

Publications and source records attributed to Y A Mostafa.

18 recordsLinked to original sources
PubMed2000

Isolation, screening and characterization of bacteriocin-producing lactic acid bacteria isolated from traditional fermented food.

100 lactic acid bacterial strains isolated from traditional fermented foods (yoghurt, milk cream, sour dough and milk) were screened for bacteriocin production. Twenty six strains producing a nisin-like bacteriocin were selected. Most of these isolates gave only a narrow inhibitory spectrum, although one showed a broad inhibitory spectrum against the indicator strains tested, this strain was determined as Lactococcus lactis. The influence of several parameters on the fermentative production of nisin by Lactococcus lactis was studied. Production of nisin was optimal at 30 degrees C and in the pH range 5.5-6.3. The effect of different sulphur and nitrogen sources on Lactococcus lactis growth and nisin production was studied. Magnesium sulfate and manganese sulfate were found to be the best sulphur sources while triammonium citrate was the best inorganic nitrogen source and meat extract, peptone and yeast extract were the best organic nitrogen source for nisin production.

Bacteria↗
PubMed1998

Personal factors and working conditions as predictors of work injuries among industrial workers.

The purpose of this study was to determine the personal factors and working conditions that predict work injuries among industrial workers. To fulfill this aim, a case control study was conducted including 2003 industrial workers who sustained a work injury and an equal number of controls. All were subjected to an interview questionnaire to collect relevant information. Moreover, records were reviewed to obtain the medical history of enrolled workers. Data revealed that workers in the index and control groups are comparable in respect to their sociodemographic characteristics. The multivariate logistic regression analysis pointed out that safety training significantly reduces the risk of work accidents among industrial workers. On the other hand, work accidents are more likely to occur in the main working shift. Moreover, workers who suffer from chronic health problems calling for surgical treatment, as well as those who reported family problems, are more likely to experience work accidents. These workers should receive considerable attention to reduce the extent of work injuries. More importantly, safety-training programs are mandatory for accident prevention in industrial settings.

Accident Prevention↗
PubMed1996

Faciometrics: a new syntax for facial feature analysis.

A little neglect appears to exist in current cephalometric soft tissue analysis. Specifically, some areas of the facial integument are not accessible to cephalometric analysis. Further, no method of frontal cephalometric soft tissue analysis has been described. Faciometrics, a new cephalometric, nonradiographic system for facial feature analysis, may carry professional diagnostic capacity to another dimension by providing an evaluation for previously inaccessible facial areas and by supplying a beginning for frontal cephalometric soft tissue analysis. The reliability and the validity of the proposed system were tested on a random sample of 20 subjects. The system was found to be reliable and valid. A method for rapid checking of facial symmetry is also described, and some equations for facial proportions are presented as guidelines for good facial esthetics. The faciometric system is proposed as a complement to, rather than a replacement for, available soft tissue cephalometric analysis.

Algorithms↗
PubMed1992

Aberrant mandibular growth: theoretical implications.

There is a multiplicity and variety of studies investigating mandibular growth. The exact role of the mandibular condyle in influencing mandibular growth is still a point of conflict. This study was conducted with six subjects who had different condylar defects. The cranium and the skeletal profile, as well as the position of the maxilla and the mandible, were investigated. In all cases, the mandible showed a tendency toward posterior rotation. The total mandibular length was reduced with deficient corpus length and ramus height. The influence of the integrity of the condylar head and its normal articulation in the temporal fossa on mandibular growth were emphasized.

Adult↗
PubMed1991

Iatrogenic pulpal reactions to orthodontic extrusion.

A careful review of the literature reveals an absence of studies about the reactions of dental pulp to orthodontic extrusion. The purpose of the present research investigation is to study the pulpal reactions and the sequence of histologic events in human dental pulp after orthodontic extrusion. The sample consisted of 36 intact maxillary first premolars of young adult orthodontic subjects. The mean age of the subjects was 18 years. Eighteen maxillary first premolars were extruded, under controlled conditions with the aid of fixed edgewise orthodontic appliances, for either 1, 2, or 4 weeks. The contralateral maxillary first premolars were not extruded and were used as controls. Immediately after removal of the appliances, all the maxillary first premolars were extracted. The pulps were histologically examined in a double-blind experiment. The results obtained from this study indicate that certain characteristic pulpal reactions arise from orthodontic extrusion. These reactions involve circulatory disturbances with congested and dilated blood vessels, odontoblastic degeneration, vacuolization and edema of the pulp tissues, and (by the fourth week) manifestation of fibrotic changes. It is speculated that the vacuolization of the pulp tissues (which occurred after the application of extrusive orthodontic forces in young adult subjects) resulted from a prolapse of the pulp, made possible by the relatively wide apical foramina. However, the odontoblastic degeneration is most probably the result of a compromised blood supply. The authors believe that this study constitutes a building block for establishing a more complete biologic foundation for orthodontic tooth movement. Further studies are suggested to reach more definitive conclusions.

Adolescent↗
PubMed1991

Soft tissue response to anterior maxillary osteotomy.

The soft tissue profile adaptation to anterior maxillary intrusion was evaluated by comparing preoperative and 6-month postoperative cephalograms of ten adult patients. Holdaway's soft tissue analysis was the method utilized for profile evaluation. Lip protrusion and interlabial gap were decreased significantly and acceptable lip competency was provided postoperatively. Other factors also played a role in controlling the final soft tissue appearance.

Adolescent↗
PubMed1990

Epidemiologic panorama of dental occlusion.

The purpose of this study was to explore the possible significant sex difference in occlusion, provide information about the occlusal variation among Egyptians, and present an epidemiologic panorama of dental occlusion among different ethnic world populations. The hypothesis was that the occlusal variation is not independent of sex. A sample of 501 female and male adult subjects was studied. Normal occlusion, Angle's classification of malocclusion, and the Dewey-Anderson modifications for typifications were recorded. Chi-square tests were used. The results obtained from this study indicate that a significant sex difference in occlusion exists for normal occlusion, Angle Class I, and Angle Class III. Further, considering an anterior crossbite as the sole indicator of an Angle Class III malocclusion is erroneous; an anterior crossbite may exist in other classes, and Angle Class III type 1 (edge-to-edge) is more prevalent than either Class III type 2 (normal anterior overbite) or type 3 (anterior crossbite). Although numerically different, occlusal variation follows a universal general distributional pattern for most world populations. Some speculations are presented for clinical implications and for research suggestions.

Adolescent↗
PubMed1987

Landmark identification in computerized posteroanterior cephalometrics.

A lack of cognition regarding the reliability of landmark identification in posteroanterior cephalometrics keeps the extracted data questionable. The present study was designed to analyze this problem for the purpose of providing certain insights. An interactive computer graphic package was developed. This package was called EA-PAX (Error Analysis of Postero-Anterior cephalometric X-ray films). A random sample of 40 clear posteroanterior cephalometric head plates was studied. The reliability of landmark identification was established. The skeletal landmarks seemed more reliable than the dental landmarks. The variation in the direction and magnitude of the error was determined for each landmark. Most landmarks had their own characteristic noncircular envelope of error. It is not the philosophy of the present authors to tell the orthodontists what to use. Rather, the philosophy is to be aware of the amount and direction of variation for a particular landmark. Taking this into consideration will enable the orthodontists to look on their cephalometric numbers with a mental awareness of the possible variations. Several clinical and research studies are suggested in the article.

Adolescent↗
PubMed1987

Mandibular anterior crowding and periodontal disease.

A short-term longitudinal study of the role of mandibular anterior crowding in inflammatory periodontal diseases. Crowded dentitions show more periodontal involvement, and the improvement after scaling disappears more rapidly.

Adult↗
PubMed1986

Influence of excision of the facial and inferior dental nerves on mandibular growth and development.

The purpose of this study was to evaluate the role of the facial and inferior dental nerves on mandibular growth and development. A sample of 10 mongrel dogs was randomly divided into two equal groups. Avulsion of the right inferior dental nerve was carried out on the first group. Surgical cutting of the extracranial portion of the right facial nerve was performed on the second group. Sham operations were made for the left sides of the mandibles of all animals. The animals were killed 3 months later and their mandibles visually and radiographically examined. Measurements were recorded in a double-blind experimental design. The data were statistically analyzed. The results obtained from this study indicate that surgical cutting of the extracranial portion of the facial nerve resulted in unilateral facial paralysis of the muscles of expression. However, after the animals were killed, no significant statistical differences were found between the nerve-devoid and sham sides of the mandible for both the facial nerve group and the inferior dental nerve group. Nevertheless, for the inferior dental nerve group, visual and radiographic examinations revealed various morphologic differences at the angular process regions of the mandibles. The impact of neural deprivation on mandibular growth and development was thus determined.

Animals↗
PubMed1983

Orchestration of tooth movement.

Recent advances in the art and mechanics of delivering orthodontic forces have achieved greater precision and control of tooth movement. The exact mechanism by which these forces orchestrate tooth movement is not thoroughly understood. An accurate understanding and precise control over the factors responsible for initiating and carrying out the tissue reaction will ultimately optimize the rate of tooth movement. An integrated hypothetical model for the mechanism of tooth movement is discussed here. This model is based on the most recent body of information available to explain how various stimuli affect bone cells. The roles played by piezoelectric responses, prostaglandin production, and biochemical factors are discussed, with particular emphasis on their importance and contribution in terms of maximizing the rate of tooth movement. The intelligent use of this knowledge will permit us to modify the orthodontic appliance and treatment regimen in order to achieve an optimum tissue response.

Alveolar Process↗
PubMed1982

A simple and rapid method for osteoclast identification using a histochemical method for acid phosphatase.

A detailed description of a simple technique for acid phosphatase demonstration in osteoclast cells is presented. The method is short, relatively uninvolved and allows the use of undecalcified bone sections. All materials and chemicals used are commercially available. The sections were stained histochemically using naphthol AS-B1 phosphoric acid as a substrate and counter stained with Mayer's Haematoxylin. Sections prepared by this method showed good results and enabled accurate measurement of osteoclast counts.

Acid Phosphatase↗
PubMed1982

Deficient nasal bone growth in the X-linked hypophosphataemic (HYP) mouse and its implication in craniofacial growth.

Mice bearing the mutant Hyp gene are characterized by craniofacial abnormalities secondary to their metabolic bone disease. X-ray cephalograms were taken of 40 normal and 29 Hyp mice at 1, 2, 3 and 4 weeks of age in one group and at weeks 6, 9 and 12 in a second. Hyp mice exhibited shorter skulls, shorter mandibles antero-posteriorly and a compressed upper face height. Both the fronto-nasal and the premaxillo-maxillary sutures in the Hyp mice were deformed and failed to close by 12 weeks of age. The deficient linear growth of the nasal bone was the most important measured variable contributing to the overall difference in the skull morphology between Hyp and normal mice. Thus this animal model is promising for elucidating the regulatory mechanisms affecting craniofacial growth.

Animals↗
PubMedDate not supplied

Increased metaphyseal bone mass in the young X-linked hypophosphatemic (Hyp) mouse.

A study of skeletal development in X-linked hypophosphatemic (Hyp) mice revealed that radiographic characteristics of the disease appear as early as seven days after birth and that an unexpected transitory metaphyseal radio-opacity occurs in the long bones of the Hyp mice. Hyperostotic osteomalacia appears at the first week, peaks at the third week, and starts to fade by the fourth week. Undecalcified bone sections of three-week-old mice revealed an increased amount of trabecular bone in the metaphysis of the Hyp mice accounting for the increased radio-opacity. Blood chemistry data in three-week-old mice showed a low plasma phosphate, a slight hypocalcemia and elevated alkaline phosphatase. Three-week-old Hyp mice had a reduced percentage of magnesium in their bone ash compared to normal. The blood chemistry data resembled those of adult Hyp mice and did not explain the increased metaphyseal bone mass. The mechanism underlying this genetic abnormality of bone is unclear.

Alkaline Phosphatase↗